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1. Sympatry leads to reduced body condition in chickadees that occasionally hybridize

   https://doi.org/10.1002/ece3.8756  

   Grabenstein, Kathryn C.; Otter, Ken A.; Burg, Theresa M.; Taylor, Scott A. (April 2022, Ecology and Evolution)

   Abstract Both abiotic and biotic drivers influence species distributions. Abiotic drivers such as climate have received considerable attention, even though biotic drivers such as hybridization often interact with abiotic drivers. We sought to explore the (1) costs of co‐occurrence for ecologically similar species that hybridize and (2) associations between ecological factors and condition to understand how abiotic and biotic factors influence species distributions. For two closely related and ecologically similar songbirds, black‐capped and mountain chickadees, we characterized body condition, as a proxy for fitness, using a 1358‐individual range‐wide dataset. We compared body condition in sympatry and allopatry with several abiotic and biotic factors using species‐specific generalized linear mixed models. We generated genomic data for a subset of 217 individuals to determine the extent of hybridization‐driven admixture in our dataset. Within this data subset, we found that ~11% of the chickadees had hybrid ancestry, and all hybrid individuals had typical black‐capped chickadee plumage. In the full dataset, we found that birds of both species, independent of demographic and abiotic factors, had significantly lower body condition when occurring in sympatry than birds in allopatry. This could be driven by either the inclusion of cryptic, likely poor condition, hybrids in our full dataset, competitive interactions in sympatry, or range edge effects. We are currently unable to discriminate between these mechanisms. Our findings have implications for mountain chickadees in particular, which will encounter more black‐capped chickadees as black‐capped chickadee ranges shift upslope and could lead to local declines in mountain chickadee populations. 

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2. Energy-twisted boundary condition and response in one-dimensional quantum many-body systems

   https://doi.org/10.1103/PhysRevB.106.155128  

   Nakai, Ryota; Guo, Taozhi; Ryu, Shinsei (October 2022, Physical Review B)
3. Urban heat and desert wildlife: rodent body condition across a gradient of surface temperatures

   https://doi.org/10.1007/s11252-023-01358-4  

   Bateman, H. L.; Allen, B. D.; Moore, M. S.; Hondula, D. M. (August 2023, Urban Ecosystems)
4. The relationship between dietary protein content, body condition, and Δ15N in a mammalian omnivore

   https://doi.org/10.1007/s00442-017-4010-5  

   Hughes, Kelli L.; Whiteman, John P.; Newsome, Seth D. (February 2018, Oecologia)
5. Feather corticosterone does not correlate with environmental stressors or body condition in an endangered waterbird

   https://doi.org/10.1093/conphys/coaa125  

   Gormally, Brenna M; van Rees, Charles B; Bowers, Emily; Reed, J Michael; Romero, L Michael (January 2020, Conservation Physiology)

   Cooke, Steven (Ed.)

   Abstract Physiological metrics are becoming popular tools for assessing individual condition and population health to inform wildlife management and conservation decisions. Corticosterone assays can provide information on how animals cope with individual and habitat-level stressors, and the recent development of feather assays is an exciting innovation that could yield important insights for conservation of wild birds. Due to the widespread enthusiasm for feather corticosterone as a potential bioindicator, studies are needed to assess the ability of this technique to detect meaningful differences in physiological stress across a variety of stressor types and intensities. We examined feather corticosterone from 144 individuals among the 13 known breeding populations of Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered waterbird, on the island of O‘ahu. These ecologically independent subpopulations are known to have low genetic connectivity and movement rates and differ largely across a number of important conditions, including level of predator management, human disturbance, proximity to urban development and conspecific population density. This system is well suited for assessing the performance of feather corticosterone as a bioindicator of different known habitat-level threats common to this and many other conservation-reliant species. We found no statistically significant relationship between feather corticosterone and level of predator control, level of human disturbance, gallinule population density, percent urban cover or body condition across all sites despite the substantial difference in stressor magnitude in our dataset. We did find that gallinules in habitats with larger population densities were in worse body condition. These findings suggest that feather corticosterone is not a consistent indicator of anthropogenic impacts on populations. Furthermore, they suggest that feather corticosterone may be a poor bioindicator of known habitat-level threats for Hawaiian gallinules and that it should be used with caution in other avian taxa of conservation concern. 

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