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1
Shepherd, Bart, Hudson T. Pinheiro, and Luiz A. Rocha. "Sometimes hard to swallow: Attempted feeding on a porcupinefish results in death of both predator and prey." Western Indian Ocean Journal of Marine Science 18, no. 2 (2019): 87–89. http://dx.doi.org/10.4314/wiojms.v18i2.9.
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Predator-prey relationships are critical components of population dynamics across all ecosystems. Interactions between predators and dangerous prey are especially likely to result in a co-evolutionary arms race. To avoid predation, porcupinefishes (Diodontidae) present a suite of physical and chemical defences, including spines, inflation, and the potent neurotoxin, tetrodotoxin, which is concentrated in the internal organs. A failed predation attempt is described here on a longspined porcupinefish, Diodon holocanthus, by a benthopelagic predator, Carangoides fulvoguttatus, resulting in the death of both the predator and the prey.
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Schenk, Amber R., Thomas K. Stevens, and Amanda M. Hale. "Predator-Prey Dynamics Are Decoupled in the Raptor Community in a Large Urban Forest." Diversity 14, no. 3 (2022): 177. http://dx.doi.org/10.3390/d14030177.
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Predator-prey dynamics are fundamental in shaping and regulating wildlife communities; however, these relationships are often altered by urbanization. An urban predation paradox, where predation rates are lower in urban areas despite an increase in predator abundance, has been observed in some predator communities. We looked for evidence of an urban predation paradox in a raptor community in a large urban forest fragment in north Texas, USA. From May–August 2019, we conducted weekly raptor surveys and deployed prey mimics along an urban-to-rural gradient within the forest fragment. We examined relationships between predation rates on mimics, predator abundance, and urbanization intensity using a variety of statistical tests. We detected 161 raptors representing eight species and found that raptor activity was significantly higher in our low urbanization sites. Of the 732 prey mimics deployed, 61 were attacked, and we found no relationship between predation rates and urbanization. Furthermore, we found no relationship between raptor activity and depredation events. Although we failed to find evidence for an urban predation paradox, our results showed a decoupling of the relationship between the abundance of predators and prey in this urban setting. The use of prey mimics is a useful tool for assessing predator-prey dynamics, and more research is necessary to fully understand the impacts of urbanization on this important ecological process.
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Essington, Timothy E., and Sture Hansson. "Predator-dependent functional responses and interaction strengths in a natural food web." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 11 (2004): 2215–26. http://dx.doi.org/10.1139/f04-146.
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Predator-dependent functional responses decouple predation mortality from fluctuations in predator abundance and therefore can prevent strong "top-down" interaction strengths in food webs. We evaluated whether contrasts in the functional response of Baltic Sea cod (Gadus morhua) were consistent with the contrasting population dynamics of two prey species, herring (Clupea harengus) and sprat (Sprattus sprattus): sprat abundance increased nearly threefold following a sharp decline in the cod population (a strong interaction), whereas herring abundance failed to increase (a weak interaction). We found striking differences in the functional response of cod on alternative prey, and these were consistent with the observed patterns in interaction strengths. Cod predation was the dominant source of mortality for age-1 and age-2 sprat but was only important for age-1 herring. Moreover, the magnitude of predation mortality on age-1 and age-2 sprat was highly sensitive to cod biomass, whereas predation mortality on herring was only moderately sensitive to cod biomass. These analyses suggest the possibility that food webs are comprised of linkages that vary with respect to the magnitude and importance of predation mortality and how this mortality varies with changes in predator abundance.
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Tapkir, Sandip D., Sanjay S. Kharat, Pradeep Kumkar, and Sachin M. Gosavi. "Effects of the invasive Tilapia on the Common Spiny Loach (Cypriniformes: Cobitidae: Lepidocephalichthys thermalis) - implications for conservation." Journal of Threatened Taxa 9, no. 9 (2017): 10642. http://dx.doi.org/10.11609/jott.2220.9.9.10642-10648.
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The introduction of invasive species leading to decline of freshwater fauna is a major concern for conservation biologists. In this study we examined the effect of introduced Tilapia on the survival of the loach Lepidocephalichthys thermalis via predation experiments with Tilapia and a native predator, the Snakehead fish Channa gachua. Examining the chemoecology of prey-predator interactions, we found that L. thermalis failed to detect water-borne cues from Tilapia but did recognize cues from C. gachua, indicating innate predator recognition. We also observed that L. thermalis can learn to associate kairomones with Tilapia when conditioned with kairomones and injured conspecific cues. Trained L. thermalis showed higher survival during Tilapia predation trials. Thus under experimental conditions the vulnerability of L. thermalis to Tilapia predation due to failure to detect chemical cues can be reduced via associative training. It remains to be determined how useful this behavioral plasticity can be in wild L. thermalis populations exposed to introduced Tilapia.
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Midway, Stephen R., Caleb T. Hasler, Tyler Wagner, and Cory D. Suski. "Predation of freshwater fish in environments with elevated carbon dioxide." Marine and Freshwater Research 68, no. 9 (2017): 1585. http://dx.doi.org/10.1071/mf16156.
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Carbon dioxide (CO2) in fresh-water environments is poorly understood, yet in marine environments CO2 can affect fish behaviour, including predator–prey relationships. To examine changes in predator success in elevated CO2, we experimented with predatory Micropterus salmoides and Pimephales promelas prey. We used a two-factor fully crossed experimental design; one factor was 4-day (acclimation) CO2 concentration and the second factor CO2 concentration during 20-min predation experiments. Both factors had three treatment levels, including ambient partial pressure of CO2 (pCO2; 0–1000 μatm), low pCO2 (4000–5000 μatm) and high pCO2 (8000–10000 μatm). Micropterus salmoides was exposed to both factors, whereas P. promelas was not exposed to the acclimation factor. In total, 83 of the 96P. promelas were consumed (n=96 trials) and we saw no discernible effect of CO2 on predator success or time to predation. Failed strikes and time between failed strikes were too infrequent to model. Compared with marine systems, our findings are unique in that we not only saw no changes in prey capture success with increasing CO2, but we also used CO2 treatments that were substantially higher than those in past experiments. Our work demonstrated a pronounced resiliency of freshwater predators to elevated CO2 exposure, and a starting point for future work in this area.
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Dennis, S. R., Mauricio J. Carter, W. T. Hentley, and A. P. Beckerman. "Phenotypic convergence along a gradient of predation risk." Proceedings of the Royal Society B: Biological Sciences 278, no. 1712 (2010): 1687–96. http://dx.doi.org/10.1098/rspb.2010.1989.
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A long-standing question in ecology is whether phenotypic plasticity, rather than selection per se , is responsible for phenotypic variation among populations. Plasticity can increase or decrease variation, but most previous studies have been limited to single populations, single traits and a small number of environments assessed using univariate reaction norms. Here, examining two genetically distinct populations of Daphnia pulex with different predation histories, we quantified predator-induced plasticity among 11 traits along a fine-scale gradient of predation risk by a predator ( Chaoborus ) common to both populations. We test the hypothesis that plasticity can be responsible for convergence in phenotypes among different populations by experimentally characterizing multivariate reaction norms with phenotypic trajectory analysis (PTA). Univariate analyses showed that all genotypes increased age and size at maturity, and invested in defensive spikes (neckteeth), but failed to quantitatively describe whole-organism response. In contrast, PTA quantified and qualified the phenotypic strategy the organism mobilized against the selection pressure. We demonstrate, at the whole-organism level, that the two populations occupy different areas of phenotypic space in the absence of predation but converge in phenotypic space as predation threat increases.
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McCormick, MI, and BA Kerrigan. "Predation and its influence on the condition of a newly settled tropical demersal fish." Marine and Freshwater Research 47, no. 3 (1996): 557. http://dx.doi.org/10.1071/mf9960557.
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The effects of predation by a common tropical piscivore on levels of variability in size and body composition of a demersal fish at settlement were examined in a series of laboratory experiments. Wild-caught, newly metamorphosed goatfish (Upeneus tragula) were placed in large tanks and subjected to predation by lizardfish (Synodus variegatus). Three trials failed to show an influence of predation on the size distribution of the newly settled prey. In a second experiment, mid-larval-phase goatfish were subjected to one of two feeding regimes; this resulted in two groups of metamorphs that differed markedly in biochemical composition (i.e. total lipid levels). Twenty fish from each treatment were randomly chosen, under the constraint of a similar mean size, and subjected to predation. Susceptibility of newly metamorphosed fish to predation by the lizardfish was independent of their initial biochemical composition. These results suggest that predation by this common tropical reef fish predator may be non-selective with respect to both size and body composition of U. tragula. Consequently, the high variability found in these body attributes at settlement may extend its influence into the juvenile population.
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Skovsted, Christian B., Glenn A. Brock, Anna Lindström, John S. Peel, John R. Paterson, and Margaret K. Fuller. "Early Cambrian record of failed durophagy and shell repair in an epibenthic mollusc." Biology Letters 3, no. 3 (2007): 314–17. http://dx.doi.org/10.1098/rsbl.2007.0006.
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Predation is arguably one of the main driving forces of early metazoan evolution, yet the fossil record of predation during the Ediacaran–Early Cambrian transition is relatively poor. Here, we present direct evidence of failed durophagous (shell-breaking) predation and subsequent shell repair in the Early Cambrian (Botoman) epibenthic mollusc Marocella from the Mernmerna Formation and Oraparinna Shale in the Flinders Ranges, South Australia. This record pushes back the first appearance of durophagy on molluscs by approximately 40 Myr.
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Neuenhoff, Rachel D., Douglas P. Swain, Sean P. Cox, et al. "Continued decline of a collapsed population of Atlantic cod (Gadus morhua) due to predation-driven Allee effects." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 1 (2019): 168–84. http://dx.doi.org/10.1139/cjfas-2017-0190.
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Most stocks of Atlantic cod (Gadus morhua) in the Northwest Atlantic collapsed in the early 1990s, with little sign of recovery since then. In the southern Gulf of St. Lawrence (sGSL), the failed recovery is due to severe increases in the natural mortality of adult Atlantic cod. We examined the role of predation by grey seals (Halichoerus grypus) in this failed recovery by directly incorporating grey seal predation in the population model for Atlantic cod via a functional response. Estimated predation mortality of adult Atlantic cod increased sharply during the cod collapse and has continued to increase, comprising the majority of mortality since the late 1990s. While predation by grey seals appeared to play a minor role in the collapse of Atlantic cod, we found it to be the main factor preventing recovery. Our results are consistent with the hypothesis that failed recovery is due to predation-driven Allee effects, a demographic effect due to the decline in cod abundance and an emergent effect resulting from increasing grey seal abundance. Under current conditions, extirpation of sGSL Atlantic cod appears likely unless there is a large decline in the abundance of grey seals.
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Schillé, Laura, Nattan Plat, Luc Barbaro, et al. "Camera traps unable to determine whether plasticine models of caterpillars reliably measure bird predation." PLOS ONE 20, no. 3 (2025): e0308431. https://doi.org/10.1371/journal.pone.0308431.
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Sampling methods that are both scientifically rigorous and ethical are cornerstones of any experimental biological research. Since its introduction 30 years ago, the method of using plasticine prey to quantify predation pressure has become increasingly popular in biology. However, recent studies have questioned the accuracy of the method, suggesting that misinterpretation of predator bite marks and the artificiality of the models may bias the results. Yet, bias per se might not be a methodological issue as soon as its statistical distribution in the samples is even, quantifiable, and thus correctable in quantitative analyses. In this study, we focus on avian predation of lepidopteran larvae models, which is one of the most extensively studied predator-prey interactions across diverse ecosystems worldwide. We compared bird predation on plasticine caterpillar models to that on dead caterpillars of similar size and color, using camera traps to assess actual predation events and to evaluate observer accuracy in identifying predation marks a posteriori. The question of whether plasticine models reliably measure insectivorous bird predation remained unanswered, for two reasons: (1) even the evaluation of experienced observers in the posterior assessment of predation marks on plasticine models was subjective to some extent, and (2) camera traps failed to reflect predation rates as assessed by observers, partly because they could only record evidence of bird presence rather than actual predation events. Camera traps detected more evidence of bird presence than predation clues on plasticine models, suggesting that fake prey may underestimate the foraging activity of avian insectivores. The evaluation of avian predation on real caterpillar corpses was probably also compromised by losses to other predators, likely ants. Given the uncertainties and limitations revealed by this study, and in the current absence of more effective monitoring methods, it remains simpler, more cost-effective, ethical, and reliable to keep using plasticine models to assess avian predation. However, it is important to continue developing improved monitoring technologies to better evaluate and refine these methods in order to advance research in this field.
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Stoleson, Scott H., and Steven R. Beissinger. "Does Risk of Nest Failure or Adult Predation Influence Hatching Patterns of the Green-Rumped Parrotlet?" Condor 103, no. 1 (2001): 85–97. http://dx.doi.org/10.1093/condor/103.1.85.
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Abstract Parent birds may adjust the onset of incubation to minimize periods of high risk of nest failure due to predation (the Nest Failure Hypothesis) or of mortality to adult birds (the Adult Predation Hypothesis). We examine temporal patterns of risk of nest failure and predation on adult females in a population of Green-rumped Parrotlets (Forpus passerinus) to determine whether those patterns explain observed patterns of incubation. Over one-third of nests (38.6%) failed completely, and an additional 2.2% failed after fledging one or more young. Most nests failed due to predation and infanticide. Because parrotlets begin incubation on the first egg, we examined a range of hypothetical failure rates for the period prior to the onset of incubation. Daily survival probabilities for nests were higher during the nestling stage than during incubation or fledging. Survival of adult females varied little through the nesting cycle, but was highest while attending nestlings. Model predictions were highly dependent on assumptions made about survival rates during the pre-incubation period. When empirically based values were used for this period, maximum productivity was achieved with first-egg incubation, consistent with observed patterns. Models were most sensitive to those parameters most difficult to estimate. This study represents the first test of the Nest Failure model with a nonpasserine or tropical species, and the first assessment of the Adult Predation model using field data.
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Bicknell, Russell D. C., and Patrick M. Smith. "Five new malformed trilobites from Cambrian and Ordovician deposits from the Natural History Museum." PeerJ 11 (October 26, 2023): e16326. http://dx.doi.org/10.7717/peerj.16326.
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Injured trilobites present insight into how a completely extinct group of arthropods responded to traumatic experiences, such as failed predation and moulting complications. These specimens are therefore important for more thoroughly understanding the Paleozoic predator-prey systems that involved trilobites. To expand the record of injured trilobites, we present new examples of injured Ogygopsis klotzi and Olenoides serratus from the Campsite Cliff Shale Member of the Burgess Shale Formation (Cambrian, Miaolingian, Wuliuan), Paradoxides (Paradoxides) paradoxissimus gracilis from the Jince Formation (Cambrian, Miaolingian, Drumian), Ogygiocarella angustissima from the Llanfawr Mudstones Formation (Middle–Late Ordovician, Darriwilian–Sandbian), and Ogygiocarella debuchii from the Meadowtown Formation, (Middle–Late Ordovician, Darriwilian–Sandbian). We consider the possible origins of these malformations and conclude that most injuries reflect failed predation. Within this framework, possible predators are presented, and we uncover a marked shift in the diversity of animals that targeted trilobites in the Ordovician. We also collate other records of injured Ogygo. klotzi and Ol. serratus, and Ogygi. debuchii, highlighting that these species are targets for further understanding patterns and records of trilobite injuries.
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Ferland-Raymond, Bastien, and Dennis L. Murray. "Predator diet and prey adaptive responses: Can tadpoles distinguish between predators feeding on congeneric vs. conspecific prey?" Canadian Journal of Zoology 86, no. 12 (2008): 1329–36. http://dx.doi.org/10.1139/z08-117.
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Predator diet can play an important role in facilitating detection of predation risk among prospective prey, and such detection should have adaptive significance in reducing mortality in environments where not all predators confer similar risk. In the laboratory, we tested behavioural and morphological responses of tadpoles from two congeneric frog species (bullfrog ( Rana catesbeiana Shaw, 1802) and mink frog ( Rana septentrionalis Baird, 1854)) to cues from an odonate predator (genus Aeshna Fabricius, 1775). In a separate experiment we found that both frog species had similar baseline vulnerability to Aeshna predation, implying that species’ responses to predators feeding on conspecific vs. congeneric prey also would be similar. Both species reduced their activity in the presence of predators feeding on tadpoles of either species vs. those fed invertebrates (Libellulidae) or not subjected to predators (controls). Bullfrog tadpoles grew bigger than controls when exposed to predators fed mink frog tadpoles only, whereas mink frogs failed to show a comparable response. Neither species exhibited changes in shape that were attributable to predator diet. Our results suggest that closely related frog species do not distinguish between predators feeding on conspecific vs. congeneric prey, implying that selection favours generalized antipredator responses when prey species are subject to similar predation risk.
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Peel, John S. "Operculum regeneration following failed predation in the Silurian gastropodOriostoma." Palaeontology 58, no. 2 (2015): 229–37. http://dx.doi.org/10.1111/pala.12154.
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Miller, Ashadee Kay, Bryan Maritz, Shannon McKay, Xavier Glaudas, and Graham J. Alexander. "An ambusher's arsenal: chemical crypsis in the puff adder ( Bitis arietans )." Proceedings of the Royal Society B: Biological Sciences 282, no. 1821 (2015): 20152182. http://dx.doi.org/10.1098/rspb.2015.2182.
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Ambush foragers use a hunting strategy that places them at risk of predation by both visual and olfaction-oriented predators. Resulting selective pressures have driven the evolution of impressive visual crypsis in many ambushing species, and may have led to the development of chemical crypsis. However, unlike for visual crypsis, few studies have attempted to demonstrate chemical crypsis. Field observations of puff adders ( Bitis arietans ) going undetected by several scent-orientated predator and prey species led us to investigate chemical crypsis in this ambushing species. We trained dogs ( Canis familiaris ) and meerkats ( Suricata suricatta ) to test whether a canid and a herpestid predator could detect B. arietans using olfaction. We also tested for chemical crypsis in five species of active foraging snakes, predicted to be easily detectable. Dogs and meerkats unambiguously indicated active foraging species, but failed to correctly indicate puff adder, confirming that B. arietans employs chemical crypsis. This is the first demonstration of chemical crypsis anti-predatory behaviour, though the phenomenon may be widespread among ambushers, especially those that experience high mortality rates owing to predation. Our study provides additional evidence for the existence of an ongoing chemically mediated arms race between predator and prey species.
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Bannister, Hannah L., Catherine E. Lynch, and Katherine E. Moseby. "Predator swamping and supplementary feeding do not improve reintroduction success for a threatened Australian mammal, Bettongia lesueur." Australian Mammalogy 38, no. 2 (2016): 177. http://dx.doi.org/10.1071/am15020.
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Broad-scale Australian mammal declines following European settlement have resulted in many species becoming regionally or globally extinct. Attempts to reintroduce native mammals are often unsuccessful due to a suboptimal number of founders being used, high rates of predation and a lack of knowledge of the reintroduction biology for the species concerned. We trialled predator swamping and supplementary feeding in an attempt to offset predation and improve reintroduction success for the burrowing bettong (Bettongia lesueur) in arid South Australia. We compared population longevity of a large release group (1266 animals) with five releases of smaller groups (~50 animals at each). We compared release sites with (n = 5) and without (n = 1) supplementary food to determine whether site fidelity, body condition and reproduction were affected, and whether these traits aided population establishment. Predator swamping did not facilitate reintroduction success, with no bettongs detected more than 122 days after release. While supplementary food increased site fidelity and persistence at release sites, bettongs failed to establish successfully at any site. Neither predator swamping nor supplementary feeding enhanced reintroduction success at our sites but results suggested that supplementary feeding should be explored as an aid to reintroduction success for Australian mammals.
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Peel, John S. "Failed predation, commensalism and parasitism on lower Cambrian linguliformean brachiopods." Alcheringa: An Australasian Journal of Palaeontology 39, no. 2 (2014): 149–63. http://dx.doi.org/10.1080/03115518.2015.964055.
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Jara, Rocío Fernanda, Ramiro Daniel Crego, Michael David Samuel, Ricardo Rozzi, and Jaime Enrique Jiménez. "Nest-site selection and breeding success of passerines in the world’s southernmost forests." PeerJ 8 (September 21, 2020): e9892. http://dx.doi.org/10.7717/peerj.9892.
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Background Birds can maximize their reproductive success through careful selection of nest-sites. The ‘total-foliage’ hypothesis predicts that nests concealed in vegetation should have higher survival. We propose an additional hypothesis, the ‘predator proximity’ hypothesis, which states that nests placed farther from predators would have higher survival. We examined these hypotheses in the world’s southernmost forests of Navarino Island, in the Cape Horn Biosphere reserve, Chile (55°S). This island has been free of mammalian ground predators until recently, and forest passerines have been subject to depredation only by diurnal and nocturnal raptors. Methods During three breeding seasons (2014–2017), we monitored 104 nests for the five most abundant open-cup forest-dwelling passerines (Elaenia albiceps, Zonotrichia capensis, Phrygilus patagonicus, Turdus falcklandii, and Anairetes parulus). We identified nest predators using camera traps and assessed whether habitat characteristics affected nest-site selection and survival. Results Nest predation was the main cause of nest failure (71% of failed nests). Milvago chimango was the most common predator, depredating 13 (87%) of the 15 nests where we could identify a predator. By contrast, the recently introduced mammal Neovison vison, the only ground predator, depredated one nest (7%). Species selected nest-sites with more understory cover and taller understory, which according to the total-foliage hypothesis would provide more concealment against both avian and mammal predators. However, these variables negatively influenced nest survival. The apparent disconnect between selecting nest-sites to avoid predation and the actual risk of predation could be due to recent changes in the predator assemblage driven by an increased abundance of native M. chimango associated with urban development, and/or the introduction of exotic mammalian ground predators to this island. These predator assemblage changes could have resulted in an ecological trap. Further research will be needed to assess hypotheses that could explain this mismatch between nest-site selection and nest survival.
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Hageman, Scott A., and Roger L. Kaesler. "Fusulinids: Predation damage and repair of tests from the Upper Pennsylvanian of Kansas." Journal of Paleontology 76, no. 1 (2002): 181–84. http://dx.doi.org/10.1017/s0022336000017455.
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The abundant fusulinids of the Hughes Creek Shale Member of the Foraker Limestone in east-central Kansas are noted for their excellent preservation (Hageman and Kaesler, 1998). Not all these fossils are in pristine condition, however, as taphonomy has taken its toll. We deal in part with necrolysis during predation, but we examine more specifically instances in which predation failed and the fusulinid survived to repair damage to its test.
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Williamson, I., and C. M. Bull. "Population ecology of the Australian frog Crinia signifera: larvae." Wildlife Research 26, no. 1 (1999): 81. http://dx.doi.org/10.1071/wr97094.
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There are few published studies of the population ecology of the larvae of Australian native anurans. In this study we report on the population dynamics of the larvae of the Australian frog Crinia signifera at a study site near Bridgewater in the Adelaide Hills, South Australia. The predator community was also monitored to provide an indication of the importance of predation in influencing the population dynamics of C. signifera larvae. Pool drying meant larvae failed to metamorphose from temporary pools in all years of the study. In a permanent pond, mortality was high and variable, with an average of 10% survival over the three years of the study. There was a complete failure to recruit to the terrestrial phase in one year. Predation pressure was thought to be the most important source of mortality in the permanent pond, although predator numbers varied considerably between and within years. When combined with information on the population ecology of the embryonic (Williamson and Bull 1994) and terrestrial (Williamson and Bull 1996) stages, the data suggest that the aquatic phase is the key phase in the population dynamics of this species.
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Booth, Andrea M., Edward O. Minot, Robin A. Fordham, and John G. Innes. "Kiore (Rattus exulans) predation on the eggs of the little shearwater (Puffinus assimilis haurakiensis)." Notornis 43, no. 3 (1996): 147. https://doi.org/10.63172/828395skyqly.
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Evidence of predation by kiore (Rattus exulans) on Little Shearwater (Puffinus assimilis haurakiensis) eggs was obtained on Lady Alice Island, Hen and Chickens Group, during the 1994 breeding season. A time-lapse video camera filmed a kiore removing a Little Shearwater egg from a nesting chamber. This egg was later recovered, showing signs of damage typical of rat predation. A kiore was also filmed breaking open and eating a punctured hen egg that had been placed in a shearwater burrow. Sixteen (55%) of the 29 nests monitored failed during incubation, and predation by kiore was the probable cause of failure for up to 75% of these nests.
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Peel, John S., Jan Ove R. Ebbestad, and Anna Lindström. "Shell Repair and Failed Predation in Lower Palaeozoic Gastropods from Sweden." Paleontological Society Special Publications 8 (1996): 305. http://dx.doi.org/10.1017/s2475262200003075.
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Itescu, Yuval, Rachel Schwarz, Shai Meiri, and Panayiotis Pafilis. "Lizard tail-loss rates on islands are not governed by longer life spans." Israel Journal of Ecology and Evolution 63, no. 2 (2017): 53–56. http://dx.doi.org/10.1163/22244662-06301011.
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We recently studied whether, on islands, predation or intraspecific aggression is the main driver of tail-loss, a common defense mechanism among lizards. We concluded the latter was the stronger driver (Itescu et al. 2017). Werner (2017) suggested that we failed to falsify an alternative hypothesis. He claims that on low-predation islands lizards live longer. Thus while tail loss is caused by predators, it accumulates over longer periods, resulting in overall higher tail-loss rates in populations experiencing weak predation. Here we test this hypothesis and three other arguments he presented, and fail to support them. We therefore adhere to our original conclusion that intraspecific aggression is the main driver of lizard tail loss on islands.
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Ortega, Catherine P., and Joseph C. Ortega. "Effects of Brown-Headed Cowbirds on the Nesting Success of Chipping Sparrows in Southwest Colorado." Condor 103, no. 1 (2001): 127–33. http://dx.doi.org/10.1093/condor/103.1.127.
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AbstractWe documented effects of Brown-headed Cowbird (Molothrus ater) parasitism on Chipping Sparrows (Spizella passerina) in southwest Colorado. Overall, 17 of 77 nests (22%) were parasitized. Abandonment was significantly higher among parasitized nests (29%) than unparasitized nests (5%). More Chipping Sparrows hatched and fledged per unparasitized nest than per parasitized nest. Reduction of host hatching and fledging rates in parasitized nests was attributable to smaller clutch size and higher abandonment. The major source of nest failure was predation, not parasitism; overall, 53% failed from predation, and only 6% failed from parasitism. There were no differences in weight, ulna length, tarsometatarsus length, or length of outermost primary between sparrow nestlings in parasitized and unparasitized nests. Only 18% of cowbird eggs laid resulted in a fledged cowbird. We observed no differences in nest placement or nest concealment between unparasitized and parasitized nests.
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Mirza, Reehan S., Maud C. O. Ferrari, Joseph M. Kiesecker, and Douglas P. Chivers. "Responses of American toad tadpoles to predation cues: behavioural response thresholds, threat-sensitivity and acquired predation recognition." Behaviour 143, no. 7 (2006): 877–89. http://dx.doi.org/10.1163/156853906778017926.
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AbstractPredation is one of the most important selective forces acting on prey animals. To respond adaptively to predation threats and increase their chances of survival, prey animals have to be able to recognize their potential predators. Even though a few studies demonstrated innate predator recognition, the vast majority of animals have to rely on learning to acquire this information. Often aquatic prey animals can learn to recognize predators when they detect conspecific alarm cues associated with cues from a novel predator. In this study, we exposed American toad (Bufo americanus) tadpoles to varying concentrations of chemical alarm cues (cues from injured conspecifics). We identified a concentration of cues which caused an overt antipredator response (supra-threshold concentration) and a lower concentration for which the prey failed to exhibit a response (sub-threshold concentration). In a second experiment, we attempted to condition the tadpoles to recognize the odour of larval dragonflies (Anax sp.) by pairing the dragonfly odour with either the sub-threshold concentration or the supra-threshold concentration of alarm cues. In both cases, the tadpoles learned to recognize the predator based on this single pairing of alarm cues and predator odour. Moreover, the intensity of the learned response was stronger for tadpoles conditioned with the supra-threshold concentration of alarm cues than the sub-threshold concentration. This is the first documented case of this mode of learning in anuran amphibians. Learned recognition of predators has important implications for survival.
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Prezant, R. S., E. J. Chapman, and A. McDougall. "In utero predator-induced responses in the viviparid snail Bellamya chinensis." Canadian Journal of Zoology 84, no. 4 (2006): 600–608. http://dx.doi.org/10.1139/z06-034.
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Predator-induced defenses are well-known adaptive responses found in many marine and freshwater organisms. These responses usually occur in juveniles or actively growing adults and reduce the ability of a predator to consume its prey. We report a predator-induced response occurring in utero in the viviparid snail Bellamya chinensis (Gray, 1863) that results in significant changes in offspring number, shell size variability of released juveniles, and juvenile shell organic content. Water-borne cues derived from a predatory crayfish ( Orconectes limosus (Rafinesque, 1817)) induced a doubling of the number of offspring released; these newly born snails were generally smaller, though more variable in size, and possessed a greater shell organic content than controls. The generally smaller size of juveniles released in the presence of a predator reflects a faster rate of generation and passage through the uterus. These responses to the presence of a predator could be adaptive by decreasing predation pressure within a population or by reducing mortality following failed attacks.
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Brodeur, Jacques, André Bouchard, and Gilles Turcotte. "POTENTIAL OF FOUR SPECIES OF PREDATORY MITES AS BIOLOGICALCONTROL AGENTS OF THE TOMATO RUSSET MITE, ACULOPS LYCOPERSICI (MASSEE) (ERIOPHYIDAE)." Canadian Entomologist 129, no. 1 (1997): 1–6. http://dx.doi.org/10.4039/ent1291-1.
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AbstractPredation experiments were conducted to identify a predator with the capacity to control the tomato russet mite, Aculops lycopersici (Massee) (Eriophyidae), in greenhouse tomato crops. The efficiency of four predatory mites species was evaluated at the individual level in the laboratory: the tydeid Homeopronematus anconai (Baker) and the phytoseiids Phytoseiulus persimilis Athias-Henriot, Amblyseius cucumeris Oudemans, and A. fallacis Garman. The first three species had already been suggested as potential control agents. Predation by P. persimilis was essentially zero on tomato russet mite, whereas H. homeopronematus failed to develop to the adult stage when fed solely with this prey. Amblyseius cucumeris developed successfully on tomato russet mite but failed to reproduce. Only A. fallacis appears to possess several of the biological attributes required to control the tomato russet mite. This species attacks all stages of the pest and displays excellent survival (.92%), adequate rate of development (6.3 days at 22 °C), and good reproductive capacity in the presence of A. lycopersici.
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Jolly, Chris J., Jonathan K. Webb, Graeme R. Gillespie, and Ben L. Phillips. "Training fails to elicit behavioral change in a marsupial suffering evolutionary loss of antipredator behaviors." Journal of Mammalogy 101, no. 4 (2020): 1108–16. http://dx.doi.org/10.1093/jmammal/gyaa060.
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Abstract Attempts to reintroduce threatened species from ex situ populations (zoos or predator-free sanctuaries) regularly fail because of predation. When removed from their natural predators, animals may lose their ability to recognize predators and thus fail to adopt appropriate antipredator behaviors. Recently, northern quolls (Dasyurus hallucatus; Dasyuromorpha: Dasyuridae) conserved on a predator-free “island ark” for 13 generations were found to have no recognition of dingoes, a natural predator with which they had coevolved on mainland Australia for about 8,000 years. A subsequent reintroduction attempt using quolls acquired from this island ark failed due to predation by dingoes. In this study, we tested whether instrumental conditioning could be used to improve predator recognition in captive quolls sourced from a predator-free “island ark.” We used a previously successful scent-recognition assay (a giving-up density experiment) to compare predator-scent recognition of captive-born island animals before and after antipredator training. Our training was delivered by pairing live predators (dingo and domestic dog) with an electrified cage floor in repeat trials such that, when the predators were present, foraging animals would receive a shock. Our training methodology did not result in any discernible change in the ability of quolls to recognize and avoid dingo scent after training. We conclude either that our particular training method was ineffective (though ethically permissible); or that because these quolls appear unable to recognize natural predators, predator recognition may be extremely difficult to impart in a captive setting given ethical constraints. Our results point to the difficulty of reinstating lost behaviors, and to the value of maintaining antipredator behaviors in conservation populations before they are lost.
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Terborgh, John W. "Toward a trophic theory of species diversity." Proceedings of the National Academy of Sciences 112, no. 37 (2015): 11415–22. http://dx.doi.org/10.1073/pnas.1501070112.
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Efforts to understand the ecological regulation of species diversity via bottom-up approaches have failed to yield a consensus theory. Theories based on the alternative of top-down regulation have fared better. Paine’s discovery of keystone predation demonstrated that the regulation of diversity via top-down forcing could be simple, strong, and direct, yet ecologists have persistently failed to perceive generality in Paine’s result. Removing top predators destabilizes many systems and drives transitions to radically distinct alternative states. These transitions typically involve community reorganization and loss of diversity, implying that top-down forcing is crucial to diversity maintenance. Contrary to the expectations of bottom-up theories, many terrestrial herbivores and mesopredators are capable of sustained order-of-magnitude population increases following release from predation, negating the assumption that populations of primary consumers are resource limited and at or near carrying capacity. Predationsensu lato(to include Janzen–Connell mortality agents) has been shown to promote diversity in a wide range of ecosystems, including rocky intertidal shelves, coral reefs, the nearshore ocean, streams, lakes, temperate and tropical forests, and arctic tundra. The compelling variety of these ecosystems suggests that top-down forcing plays a universal role in regulating diversity. This conclusion is further supported by studies showing that the reduction or absence of predation leads to diversity loss and, in the more dramatic cases, to catastrophic regime change. Here, I expand on the thesis that diversity is maintained by the interaction between predation and competition, such that strong top-down forcing reduces competition, allowing coexistence.
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Low, Petah A., Clare McArthur, and Dieter F. Hochuli. "Dealing with your past: experience of failed predation suppresses caterpillar feeding behaviour." Animal Behaviour 90 (April 2014): 337–43. http://dx.doi.org/10.1016/j.anbehav.2014.02.020.
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Godfrey, Stephen J., and Brian L. Beatty. "A Miocene cetacean vertebra showing a partially healed longitudinal shear-compression fracture, possibly the result of domoic acid toxicity or failed predation." Palaeontologia Electronica 25, no. 3 (2022): 1–16. https://doi.org/10.26879/1171.
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Godfrey, Stephen J., Beatty, Brian L. (2022): A Miocene cetacean vertebra showing a partially healed longitudinal shear-compression fracture, possibly the result of domoic acid toxicity or failed predation. Palaeontologia Electronica (a28) 25 (3): 1-16, DOI: 10.26879/1171, URL: http://dx.doi.org/10.26879/1171
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Simpson, Keith, James N. M. Smith, and John P. Kelsall. "Correlates and consequences of coloniality in great blue herons." Canadian Journal of Zoology 65, no. 3 (1987): 572–77. http://dx.doi.org/10.1139/z87-089.
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Sixty percent of the breeding great blue herons (Ardea herodias) in a colony at Pender Harbour, British Columbia, were individually marked to test three hypotheses concerning the benefits of colonial breeding. (i) Most herons fed near the site of the colony, but neighbours or members of a pair did not tend to choose adjacent feeding sites, as predicted by the information center hypothesis. Food supply was predictably distributed in time and space, and birds that did most of their feeding outside Pender Harbour bred less successfully than locally feeding birds. (ii) Nests that failed because of predation were nearer to the edge of the colony in 1978 but not in 1979. The colony was abandoned in 1980 after 2 years of high predation. Predation may, therefore, select for colonial breeding in herons, but heavy predation may force colony abandonment. (iii) Most herons chose new nest sites and new mates each year. The colony site may therefore serve as an assembly site for mate finding. Mate finding and avoidance of predation are therefore more likely to explain coloniality in great blue herons than are advantages associated with finding food.
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Hart, Megan E., Anna Perez-Umphrey, Philip C. Stouffer, et al. "Nest survival of Seaside Sparrows (Ammospiza maritima) in the wake of the Deepwater Horizon oil spill." PLOS ONE 16, no. 10 (2021): e0259022. http://dx.doi.org/10.1371/journal.pone.0259022.
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In 2010, the Deepwater Horizon oil spill released an estimated 4.9 million barrels of oil into the Gulf of Mexico, damaging coastal ecosystems. Seaside Sparrows (Ammospiza maritima)—a year-round resident of Gulf Coast salt marshes—were exposed to oil, as shown by published isotopic and molecular analyses, but fitness consequences have not been clarified. We monitored nests around two bays in Plaquemines Parish, Louisiana, USA from 2012–2017 to assess possible impacts on the nesting biology of Seaside Sparrows. A majority of nests failed (76% of known-fate nests, N = 252 nests, 3521 exposure-days) during our study, and predation was the main cause of nest failure (~91% of failed nests). Logistic exposure analysis revealed that daily nest survival rate: (1) was greater at nests with denser vegetation at nest height, (2) was higher in the more sheltered bay we studied, (3) decreased over the course of the breeding season in each year, and (4) was not correlated with either sediment polycyclic aromatic hydrocarbon concentrations or estimated predator abundance during the years for which we had those data. Although the Deepwater Horizon spill impacted other aspects of Seaside Sparrow ecology, we found no definitive effect of initial oiling or oiled sediment on nest survival during 2012–2017. Because predation was the overwhelming cause of nest failure in our study, additional work on these communities is needed to fully understand demographic and ecological impacts of storms, oil spills, other pollutants, and sea-level rise on Seaside Sparrows and their predators.
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Ortega-Solis, Lidiana Esther, Daniel Galindo-Espinosa, Elsa Margarita Figueroa-Esquivel, Uki Rosales-Huerta, John Cavitt, and Fernando Puebla-Olivares. "Nest survival of the Snowy Plover Charadrius nivosus at Marismas Nacionales, Nayarit." Huitzil Revista Mexicana de Ornitología 23, no. 1 (2022): e634. http://dx.doi.org/10.28947/hrmo.2022.23.1.609.
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Breeding habitat loss and nest predation are considered the main causes of Snowy Plover (Charadrius nivosus) populations decline worldwide. We evaluated the effects of season, nest age, distance to nearest vegetation patch, distance to nearest body of water, habitat type, and nesting substrate on the daily survival rate of Snowy Plover nests. During 2014-2015, we located 84 nests in Las Garzas-Chahuin-Chihua lagoon in Marismas Nacionales, Nayarit, Mexico. We used MARK software to estimate daily nest survival rate, which was 0.969 (95% CI = 0.95 - 0.97) for both breeding seasons combined, with a 42% finite nesting success. A total of 44 nests (52%) were successful, while 40 (48%) failed. The main causes of nest failure were predation (n = 30; 75% of failed nests) and flooding (n = 9; 22.5% of failed nests); one nest was lost due to unknown causes (2.5%). Daily survival rate increased with nest age and distance from the nearest vegetation patch. By contrast, daily survival rate decreased with the progression of the breeding season; a higher probability of nest success was evident when established early in the breeding season. Our results show the importance of different positive and negative factors influencing nest survival that might be considered as part of conservation strategies.
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Coleman, Andrea, Dominique Richardson, Robin Schechter, and Daniel T. Blumstein. "Does habituation to humans influence predator discrimination in Gunther's dik-diks ( Madoqua guentheri )?" Biology Letters 4, no. 3 (2008): 250–52. http://dx.doi.org/10.1098/rsbl.2008.0078.
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Animals living around humans may habituate to us, but little is known about the consequences of this habituation. Some wildlife managers assume that habituation to humans makes individuals less likely to respond to natural predators, which is something to be avoided in captive breeding programmes where animals are destined for release. We conducted a playback experiment where we broadcast the sounds of a terrestrial predator and the song from a non-threatening bird to Gunther's dik-diks ( Madoqua guentheri ), a small ungulate that is vulnerable to many predators, in areas where dik-diks were and were not habituated to humans. Contrary to our expectation, habituated dik-diks discriminated the predator sounds from the birdsong, while unhabituated dik-diks failed to make this discrimination. Our results demonstrate that humans may influence predation hazard assessment, but we should not generally assume that human-habituated animals will be especially vulnerable to predators.
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Mc Cann, Frank, Armando H. Escobedo-Galván, and Fabio G. Cupul-Magaña. "The best hunter loses his prey: failed attempts at predation by the american crocodile on the mesoamerican turtle." Herpetología Mexicana, no. 4 (December 30, 2022): 26–31. http://dx.doi.org/10.69905/vhdafz25.
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The predation attempts of the american crocodile Crocodylus acutus on the mesoamerican turtle Trachemys ornata allow us to assume that the turtle could be part of its diet, however, there may also be a benefit in the protection of its clutch by the crocodile.
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Ebbestad, Jan Ove R., and Anette E. S. Högström. "Shell repair following failed predation in two Upper Ordovician brachiopods from central Sweden." GFF 122, no. 3 (2000): 307–12. http://dx.doi.org/10.1080/11035890001223307.
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Rothschild, Bruce M., and Robert Depalma. "Skin pathology in the Cretaceous: Evidence for probable failed predation in a dinosaur." Cretaceous Research 42 (May 2013): 44–47. http://dx.doi.org/10.1016/j.cretres.2013.01.005.
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Priddel, David, and Robert Wheeler. "Efficacy of Fox Control in Reducing the Mortality of Released Captive-reared Malleefowl, Leipoa ocellata." Wildlife Research 24, no. 4 (1997): 469. http://dx.doi.org/10.1071/wr96094.
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The effectiveness of localised, high-intensity fox baiting in reducing the incidence of fox predation was examined after captive-reared malleefowl were released and their survival monitored. Malleefowl released into baited areas survived longer than those released into nearby areas that had not been baited. Survival in both baited and non-baited areas was greater than that prior to any fox control. Of those malleefowl released, 29% were still alive three months later, whereas prior to fox control almost all were killed by foxes within a month of release. Despite the improvement in survival of malleefowl, fox predation remained the primary cause of malleefowl mortality. The number of baits taken by foxes indicated a large fox population and a high level of reinfestation. A more widespread, but less intensive, regime of baiting failed to further enhance the survival of malleefowl. Malleefowl were also particularly vulnerable to predation by raptors in habitats where the mallee was interspersed with areas of open woodland, and where the understorey was sparse. Fox baiting will need to be frequent, intensive and widespread to reduce fox density to levels where predation no longer threatens the survival or recovery of malleefowl populations.
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Kawaguchi, Manami, and Takashi Kuriwada. "Effect of predator cue on escape and oviposition behaviour of freshwater snail." Behaviour 157, no. 7 (2020): 683–97. http://dx.doi.org/10.1163/1568539x-bja10018.
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Abstract When suitability of sites for parent is incompatible with that for their eggs, parent–offspring conflict occurs — the parent must choose between the optimal oviposition site for eggs and that suitable for itself. We examined effects of predator cue on parental habitat use and oviposition site in Physa acuta. We assessed desiccation risk in eggs and the relationship between water depth and predation risk. Predator cues induced the elevation of parental habitat away from the bottom but had no effect on the oviposition site. Oviposition site choice is not by-product of escape response. Eggs that were exposed to desiccation failed to hatch, indicating high desiccation risk. Eggs laid at deeper levels were at higher risk of stripping from oviposition substrates by crayfishes. Although the middle-water level would be suitable oviposition sites, the parents selected an oviposition site in the upper level. There are other benefits and costs of oviposition site selection.
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Hebblewhite, Mark, Daniel H. Pletscher, and Paul C. Paquet. "Elk population dynamics in areas with and without predation by recolonizing wolves in Banff National Park, Alberta." Canadian Journal of Zoology 80, no. 5 (2002): 789–99. http://dx.doi.org/10.1139/z02-058.
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Gray wolves (Canis lupus) recolonized the Bow Valley of Banff National Park in the mid-1980s after a 30-year absence. Wolves recolonized one zone of the Bow Valley in 1985 and another in 1991, but human activity excluded wolves from a third zone throughout the study. Elk (Cervus elaphus) are the primary prey of wolves in Banff National Park. We studied the effects of wolf predation, snow depth, elk density, and human-caused mortality on the elk population growth rate in the three different wolf recolonization treatments from 1985 to 2000. We constructed a set of generalized linear models of factors affecting population growth, and used Akaike Information Criteria to guide model selection and inference. In the low wolf predation zone, elk population growth was density-dependent and limited by human-caused mortality. In the zone that wolves recolonized in 1991, elk population growth was limited by the combined effects of snow depth and wolf predation after wolf recolonization, in addition to preexisting mortality caused by humans and other predators. Our correlative approach failed to yield insights into population dynamics in the zone where wolves were present throughout the study. However, by comparing zones we demonstrate important differences in ungulate population dynamics in the presence and absence of wolf predation.
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Marzluff, John M., John C. Withey, Kara A. Whittaker, et al. "Consequences of Habitat Utilization by Nest Predators and Breeding Songbirds Across Multiple Scales in an Urbanizing Landscape." Condor 109, no. 3 (2007): 516–34. http://dx.doi.org/10.1093/condor/109.3.516.
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Abstract Abstract. Nest predation may influence habitat selection by birds at multiple spatial scales. We blended population and community ecology to investigate this possibility for 15 species of forest songbirds and their diurnal nest predators (corvids and sciurids) in 28 1 km2 sites near Seattle, Washington, from 1998 to 2004. We determined whether songbirds were positively or negatively associated with nest predators at three spatial scales, and whether their co-occurrence affected reproductive success. At the largest ‘neighborhood’ scale (1 km2 areas that included suburban and exurban development and second-growth forest remnants), nest predators and their prey were positively or negatively correlated according to general species-specific habitat associations. At the intermediate ‘forest patch’ scale (among remnant forested areas 0.5 to 70 ha), associations between predators and prey were generally weak. At the smallest ‘within patch’ scale (multiple 50 m radius survey plots within each forest patch), some songbird species avoided areas with greater predator use, particularly by Steller's Jays (Cyanocitta stelleri). Failed nests and territories tended to be in locations of higher predator occurrence (especially of corvids) than successful ones, but at the largest 1 km2 neighborhood scale relative abundance of nest predators was not correlated with the fate of nesting attempts or annual reproductive success. Reproductive success was generally high, with 52% of all nests and 49% of all territories fledging at least one young (for all species and years combined). Nest predation influenced some species' use of resources, but was not a strong influence on overall reproductive success or community structure.
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Díaz-Guzmán, Hilda, Edgar J. González, and Consuelo Bonfil. "Are the Interactions between Oaks and Pre-Dispersal Seed Predators Retained in Urban Environments? An Analysis of Two Quercus Species in Southern Mexico City." Diversity 14, no. 5 (2022): 351. http://dx.doi.org/10.3390/d14050351.
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As urbanization proceeds, natural ecosystems surrounding cities are transformed, but usually some elements persist, notably trees from forest ecosystems. However, it is still unknown the extent to which isolated trees, immersed in an urban matrix, maintain their interactions with insects that feed on their seeds. In this work we analyzed pre-dispersal seed predation by the two main groups of insects, weevils (Coleoptera; Curculionidae) and moths (Lepidoptera: Tortricidae), whose larvae feed on the acorns of two oak species (Quercus rugosa and Q. castanea). We compared these interactions between trees located in a protected forested area and trees isolated in an urban matrix. Our hypothesis was that, since pre-dispersal seed predation depends on insect dispersal, acorns from isolated trees would have lower predation levels than acorns from trees in the forest. A second hypothesis, based on reports that moths exhibit larger dispersal distances than weevils, was that isolated trees would have higher predation levels from moths than from weevils compared to their respective proportions in forest trees. Finally, we expected that moth predation would increase with seed size, as it does in weevils. We collected 1200 acorns of the two oak species (ten trees per species) in a protected oak forest and a nearby highway in southern Mexico City. From the whole sample, 17.3% of the acorns were predated by weevils and 3.8% by moths. The probability of predation was larger in acorns from trees in the forest (0.30) than in those from isolated trees (0.07), which confirmed the first hypothesis; tree species identity did not have a significant effect on the proportion of predated acorns. When only predated acorns were analyzed, predation by weevil larvae was larger than predation by moths in both oak species, although the probability of predation by weevils was higher in the oak species having large acorns (Q. rugosa, 0.93), than in the species with small acorns (Q. castanea, 0.63). Inversely, predation by moths was higher in Q. castanea (0.37) than in Q. rugosa (0.07). Seed predation decreased similarly for weevils and moths in isolated trees, so we failed to find support for our second hypothesis. A positive relationship between seed predation by weevils and seed size was found in Q. rugosa but not in Q. castanea; seed size did not affect predation by moth larvae. Therefore, although isolated trees in the urban matrix harbor smaller populations of pre-dispersal seed predators than forest trees, their interactions with the two main groups of insects feeding on acorns are maintained, which points to their importance for the conservation of urban biodiversity.
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Ebbestad, J. O. R., and J. S. Peel. "Attempted predation and shell repair in Middle and Upper Ordovician gastropods from Sweden." Journal of Paleontology 71, no. 6 (1997): 1007–19. http://dx.doi.org/10.1017/s002233600003599x.
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Repaired shell injuries are reported in 11 specimens including six genera and eight species of gastropods from the upper Middle Ordovician (Caradoc) Kullsberg Limestone and the Upper Ordovician (Ashgill) Boda Limestone, Siljan district, Sweden. The specimens are of different sizes and morphologies, including one isostrophic, three low-spired, and six moderately high-spired turbinate forms. Single and repeated episodes of shell damage and subsequent repair are preserved, the breaks ranging from simple arcuate or scalloped fractures to removal of large sections of the apertural margin. Both early and late growth stages show damage, but the injuries are usually restricted to only one whorl. No shell repairs were discovered on the 65 more or less complete specimens of the subulitids, although the smooth shell makes observation difficult. Injuries in the Siljan samples are found in both microgastropods and large specimens, but the sample is too small for meaningful quantification. The shell repair frequency is about 7 percent, based on examination of 404 specimens (54 from Kullsberg Limestone and 350 from Boda Limestone). Most of the repaired injuries are attributed to failed predation, adding significantly to the Lower Paleozoic documentation of predation on gastropods. The gastropod shells are morphologically weak by modern standards, but do show some architectural strengthening features such as narrow apertures, collabral or spiral threads, and other ornamentation. The identity of the predator(s) is unknown.
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Stanbury, Mailee, and James V. Briskie. "I smell a rat: Can New Zealand birds recognize the odor of an invasive mammalian predator?" Current Zoology 61, no. 1 (2015): 34–41. http://dx.doi.org/10.1093/czoolo/61.1.34.
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Abstract Although it is well known that birds can assess predation risk through visual and auditory cues, there has been little research into whether similar processes occur with olfactory cues. We examined the role of odor cues in assessing nest predation risk in four species of passerine birds in New Zealand. We compared the ability of two introduced European species (common starling Sturnus vulgaris and song thrush Turdus philomelos) and two native New Zealand species (rifleman Acanthisitta chloris and South Island robin Petroica australis) to respond to the scent of rat urine placed in the nest. Rats are an introduced predator in New Zealand and we expected the native birds, which did not co-evolve with any mammalian predators, to lack behavioral adaptations to the scent of rats at their nest. As expected, both riflemen and robins failed to show any change in their behavior at their nest when rat urine was present compared to a control period in which no scent was present. However, a similar lack of response was observed in the introduced song thrush; only the common starling changed its behavior in the presence of the rat urine. Starlings with rat urine at the nest box were more likely to hesitate before entering and they also approached the nest, but refused to enter more often in the presence of rat scent. Both responses suggest they detected the presence of a predator and changed their behavior to minimize risk to themselves. Although based on a small number of species, our results suggest that responses to predator scent may be less common in New Zealand species, and may be a factor contributing to the vulnerability of native birds to introduced mammalian predators.
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Tsasi, Gerasimia, Efstratios Valakos, Chrysi Simou, and Panayiotis Pafilis. "Predation pressure, density-induced stress and tail regeneration: a casual-nexus situation or a bunch of independent factors?" Amphibia-Reptilia 30, no. 4 (2009): 471–82. http://dx.doi.org/10.1163/156853809789647022.
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AbstractCaudal autotomy, the self-induced tail shedding from the body, is a common defensive strategy in lizards. Tail loss is followed rapidly by regeneration, revealing the importance of a fully functional tail. Predation pressure has been traditionally correlated with autotomy performance. However there is a lack of evidence regarding the impact of predation regime on tail regeneration. Another important factor that has been neglected is the population density. Though it is well established that crowding alters various life-history traits, the impact of density on caudal regeneration remains understudied. In this paper we compared three island populations of the Aegean Wall Lizard (Podarcis erhardii) that have evolved under different levels of predation pressure: whereas the Naxos population is exposed to numerous predators the Kopries and Daskalio islet populations experience low predation pressure. To evaluate the effect of density-induced stress on caudal regeneration, lizards were treated under two conditions of housing, in single and crowded (six individuals) terraria. Tail sheding occurred prior to this treatment following a standardised method. The length of regenerated tail was recorded weekly. Regeneration rate was higher in single terraria when compared to crowded, reflecting the negative impact of crowding. However we failed to detect any statistically significant difference between single and crowded terraria in the case of Naxos. We believe that the underlying reason must be the heavy predation pressure under which rapid tail regeneration, even under unfavourable conditions, is crucial for survival. It seems that the imperious need for regeneration counteracts density-induced stress.
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De Solla, Shane R., and Kim J. Fernie. "Is Cost of Locomotion the Reason for Prolonged Nesting Forays of Snapping Turtles, Chelydra serpentina?" Canadian Field-Naturalist 118, no. 4 (2004): 610. http://dx.doi.org/10.22621/cfn.v118i4.67.
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Prolonged nesting forays were observed in five gravid Snapping Turtles (Chelydra serpentina), in 1999 and 2001. For all observations, the females began exploratory nest excavations but failed to oviposit. Subsequently, all five females sought refuge either by burying themselves in substrate, or by seeking shade under vegetation, presumably to wait until the following day to resume nesting activities. By contrast, most observations of failed nesting resulted in the females abandoning the nesting site and returning immediately to water. Although prolonged nesting attempts in other turtle species (i.e. kinosternids) likely are associated with rainfall or predation risk, we speculate that these prolonged nesting attempts in Snapping Turtles reduced the cost of terrestrial travel.
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Kleindorfer, Sonia, Lauren K. Common, and Petra Sumasgutner. "Nesting Success and Nesting Height in the Critically Endangered Medium Tree Finch (Camarhynchus pauper)." Birds 2, no. 4 (2021): 427–44. http://dx.doi.org/10.3390/birds2040032.
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When different introduced species across trophic levels (parasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and infer causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos Archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (n = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with avian vampire fly larvae (Philornis downsi). We attributed the cause of death to avian vampire fly if chicks were found dead in the nest with fly larvae or pupae (45%) present. We inferred avian (either Asio flammeus galapagoensis or Crotophaga ani) predation (24%) if the nest was empty but dishevelled; and black rat (Rattus rattus) predation (20%) if the nest was empty but undamaged. According to these criteria, the highest nests were depredated by avian predators, the lowest nests by rats, and intermediate nests failed because of avian vampire fly larvae. In conclusion, there is no safe nesting height on Floreana Island under current conditions of threats from two trophic levels (introduced parasitic dipteran, introduced mammalian/avian predators; with Galápagos Short-Eared Owls being the only native predator in the system).
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Lee, Michael. "Failed attempts to reintroduce bellbirds (Anthornis melanura) to Waiheke Island, Hauraki Gulf, 1988-91." Notornis 52, no. 3 (2005): 150. https://doi.org/10.63172/353425epbwac.
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New Zealand bellbirds (Anthornis melanura) disappeared suddenly from the northern New Zealand mainland and several large northern islands in the late 19th century. During the past 75 years, several unsuccessful attempts were made to reintroduce them. Between 1988 and 1991, four translocations (111 birds) were made to Waiheke Island near Auckland, sourced from Kaingaroa (21 birds) and Cuvier Island (90 birds). The birds were conspicuous immediately after release but became progressively less visible within six months and the translocations failed. While the cause(s) of failure are unknown, predation by mammalian predators, especially ship rats (Rattus rattus) is likely to have been a critical factor. Other possible reasons for failure of bellbird translocations are discussed, along with the reasons why original bellbird populations disappeared from northern New Zealand and subsequently failed to re-establish.
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Parker, Brian R., Frank M. Wilhelm, and David W. Schindler. "Recovery of Hesperodiaptomus arcticus populations from diapausing eggs following elimination by stocked salmonids." Canadian Journal of Zoology 74, no. 7 (1996): 1292–97. http://dx.doi.org/10.1139/z96-144.
Full textAbstract:
Hesperodiaptomus arcticus, a predatory calanoid copepod, was eliminated from two alpine lakes within 6 years of stocking with salmonids. Using historical and contemporary Zooplankton and fish data, sediment analysis for diapausing eggs, and experiments on predation of Gammarus lacustris on diapausing eggs of H. arcticus, we assess the fate of these populations 35 years after fish stocking. In Pipit Lake, in which the trout introduction failed within 21 years, we propose that H. arcticus recovered as a result of hatching of diapausing eggs held in the sediments. In Snowflake Lake the diapausing egg bank was exhausted prior to the loss of the fish population 25 years after first stocking and H. arcticus recovery did not occur. Experimental studies indicate that G. lacustris predation on diapausing eggs probably occurs within the sediments. Combined with a 10-fold difference in G. lacustris density between Snowflake and Pipit lakes the results of the predation experiments imply that G. lacustris had a strong negative impact on the abundance of diapausing eggs held in Snowflake Lake sediments and therefore reduced the ability of the population to recover following perturbation.