1. Bayesian stable isotope mixing models (BSIMMs) for δ 13 C and δ 15 N can be a useful tool to reconstruct diets, characterize trophic relationships, and assess spatiotemporal variation in food webs. However, use of this approach typically requires a priori knowledge on the level of enrichment occurring between the diet and tissue of the consumer being sampled (i.e. a trophic discrimination factor or TDF). 2. Trophic discrimination factors derived from captive feeding studies are highly variable, and it is challenging to select the appropriate TDF for diet estimation in wild populations. We introduce a novel method for estimating TDFs in a wild population-a proportionally balanced equation that uses high-precision diet estimates from nest cameras installed on a subset of nests in lieu of a controlled feeding study (TDF CAM). 3. We tested the ability of BSIMMs to characterize diet in a free-living population of gyrfalcon Falco rusticolus nestlings by comparing model output to high-precision nest camera diet estimates. We analysed the performance of models formulated with a TDF CAM against other relevant TDFs and assessed model sensitivity to an informative prior. We applied the most parsimonious model inputs to a larger sample to analyse broad-scale temporal dietary trends. 4. Bayesian stable isotope mixing models fitted with a TDF CAM and uninformative prior had the best agreement with nest camera data, outperforming TDFs derived from captive feeding studies. BSIMMs produced with a TDF CAM produced reliable diet estimates at the nest level and accurately identified significant temporal shifts in gyrfalcon diet within and between years. 5. Our method of TDF estimation produced more accurate estimates of TDFs in a wild population than traditional approaches, consequently improving BSIMM diet estimates. We demonstrate how BSIMMs can complement a high-precision diet study by expanding its spatiotemporal scope of inference and recommend this integrative methodology as a powerful tool for future trophic studies.
Social distancing has become the most prominent measure many countries have implemented to combat the spread of COVID-19. The aim of the current study was to explore the potential role of empathy and self-construal styles, as individual personality traits, on self-reported social distancing. Participants completed the Interpersonal Reactivity Index (a multi-dimensional measure of trait-levels of empathy), the Singelis Self-Construal Scale (a measure of self-construal styles), and were asked to rate their level of social distancing and how much they endorsed social distancing on a five-point Likert-scale. Across a large and diverse sample (with participants collected from Canada, United Kingdom, Sweden, and United States; total n = 967), results showed that trait-levels of empathic concern (EC) and perspective taking (PT) positively correlates with social distancing. However, we did not find evidence to suggest that trait-levels of personal distress correlates with social distancing. We interpret these findings as suggesting that empathy, both its altruistic (EC) and cognitive (PT) dimensions, plays an important role in motivating people to socially distance and should be emphasized during times of crisis. Furthermore, we suggest that emphasizing a person’s self-distress during times of crisis may not be an effective approach in promotion social distancing policies (or other prosocial behaviors). We also found that both independence and interdependence self-construal styles positively correlates with social distancing. While we expected the latter result, we did not expect the former. This suggests that more work is needed to fully understand how self-construal styles, along with their cultural level analogs (i.e., Individualism-Collectivism), influences social distancing. Overall, these results provide us with novel multi-national data about the role of individual differences on social distancing tendencies specifically, and human behavior during a global health crisis more generally.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Scoping reviews, in which the literature on a given topic is systematically collated and summarized, aid literature searches and highlight knowledge gaps on a given topic, thus hastening scientific progress and informing conservation efforts. Because much research and conservation is targeted at the species level, ornithology and bird conservation would benefit from scoping reviews of individual species. We present and apply a framework for scoping reviews for three disparate raptor species: California Condor Gymnogyps californianus, Harpy Eagle Harpia harpyja and Gyrfalcon Falco rusticolus. We consulted expert panels to develop appropriate search strings and lists of essential literature, i.e. ‘benchmark articles’. We searched Web of Science, Scopus and Google Scholar. Searches for California Condor, Harpy Eagle and Gyrfalcon returned 268, 138 and 343 articles, respectively, that discuss, review or collect empirical data for the focal species. Our searches returned all benchmark articles identified by species experts, indicating that the searches captured the most important work on each species. We coded each study according to the topic addressed, country and month in which data were collected. We also coded threats, stresses and conservation actions addressed by studies, following definitions used by the International Union for the Conservation of Nature (IUCN) during Red List assessments. Literature summaries for each species include the number of studies addressing certain topics, monthly timing of research and global maps of research focus. Our coding scheme revealed important knowledge gaps for each species. Effects of conservation actions on wild individuals were less studied for California Condors. Harpy Eagles were less studied outside of Brazil and Panama, and Gyrfalcons were less studied outside of their breeding season. Scoping reviews of the world's bird species would help to identify critical knowledge gaps, thereby aiding the global effort to assuage the sixth mass extinction.
Intra-and inter-speci c resource partitioning within predator communities is a fundamental component of trophic ecology, and one proposed mechanism for how populations partition resources is through individual niche variation. The Niche Variation Hypothesis (NVH) predicts that interindividual trait variation leads to functional trade-offs in foraging e ciency, resulting in populations comprised of individual dietary specialists. A modi ed version of the NVH [mNVH] predicts niche specialization is plastic and responsive to uctuating resource availability. We quanti ed niche overlap and tested the mNVH within an Arctic raptor guild, focusing on three species that employ different foraging strategies: Golden Eagles (generalists); Gyrfalcons (facultative specialists); and Rough-legged Hawks (specialists).Tundra ecosystems exhibit cyclic populations of arvicoline rodents (lemmings and voles), providing a unique system under which to examine interannual uctuations in predator resource availability. Using blood δ 13 C & δ 15 N values from 189 raptor nestlings on Alaska's Seward Peninsula (2014-2019), we calculated isotopic niche width and used Bayesian stable isotope mixing models (BSIMMs) to characterize individual specialization and test the mNVH. We observed a high degree of isotopic niche overlap between the three species and variable trophic responses to different stages of the arvicoline rodent cycle. Elevated arvicoline rodent abundance corresponded to reduced niche overlap among species and increased individual specialization in Golden Eagles and Gyrfalcons. Further, Gyrfalcons displayed a positive relationship between individual specialization and population niche width on an interannual basis consistent with the mNVH. Our ndings suggest plasticity in niche specialization may reduce intra-and inter-speci c resource competition under dynamic ecological conditions.
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