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1. Metabolic reduction after long-duration flight is not related to fat-free mass loss or flight duration in a migratory passerine

   https://doi.org/10.1242/jeb.215384  

   Gerson, Alexander R.; DeSimone, Joely G.; Black, Elizabeth C.; Dick, Morag F.; Groom, Derrick J. (October 2020, The Journal of Experimental Biology)

   null (Ed.)

   ABSTRACT Migratory birds catabolize large quantities of protein during long flights, resulting in dramatic reductions in organ and muscle mass. One of the many hypotheses to explain this phenomenon is that decrease in lean mass is associated with reduced resting metabolism, saving energy after flight during refueling. However, the relationship between lean body mass and resting metabolic rate remains unclear. Furthermore, the coupling of lean mass with resting metabolic rate and with peak metabolic rate before and after long-duration flight have not previously been explored. We flew migratory yellow-rumped warblers ( Setophaga coronata ) in a wind tunnel under one of two humidity regimes to manipulate the rate of lean mass loss in flight, decoupling flight duration from total lean mass loss. Before and after long-duration flights, we measured resting and peak metabolism, and also measured fat mass and lean body mass using quantitative magnetic resonance. Flight duration ranged from 28 min to 600 min, and birds flying under dehydrating conditions lost more fat-free mass than those flying under humid conditions. After flight, there was a 14% reduction in resting metabolism but no change in peak metabolism. Interestingly, the reduction in resting metabolism was unrelated to flight duration or to change in fat-free body mass, indicating that protein metabolism in flight is unlikely to have evolved as an energy-saving measure to aid stopover refueling, but metabolic reduction itself is likely to be beneficial to migratory birds arriving in novel habitats. 

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2. Improving inferences about private land conservation by accounting for incomplete reporting

   https://doi.org/10.1111/cobi.13673  

   Williamson, Matthew A.; Dickson, Brett G.; Hooten, Mevin B.; Graves, Rose A.; Lubell, Mark N.; Schwartz, Mark W. (March 2021, Conservation Biology)

   Abstract Private lands provide key habitat for imperiled species and are core components of function protectected area networks; yet, their incorporation into national and regional conservation planning has been challenging. Identifying locations where private landowners are likely to participate in conservation initiatives can help avoid conflict and clarify trade‐offs between ecological benefits and sociopolitical costs. Empirical, spatially explicit assessment of the factors associated with conservation on private land is an emerging tool for identifying future conservation opportunities. However, most data on private land conservation are voluntarily reported and incomplete, which complicates these assessments. We used a novel application of occupancy models to analyze the occurrence of conservation easements on private land. We compared multiple formulations of occupancy models with a logistic regression model to predict the locations of conservation easements based on a spatially explicit social–ecological systems framework. We combined a simulation experiment with a case study of easement data in Idaho and Montana (United States) to illustrate the utility of the occupancy framework for modeling conservation on private land. Occupancy models that explicitly accounted for variation in reporting produced estimates of predictors that were substantially less biased than estimates produced by logistic regression under all simulated conditions. Occupancy models produced estimates for the 6 predictors we evaluated in our case study that were larger in magnitude, but less certain than those produced by logistic regression. These results suggest that occupancy models result in qualitatively different inferences regarding the effects of predictors on conservation easement occurrence than logistic regression and highlight the importance of integrating variable and incomplete reporting of participation in empirical analysis of conservation initiatives. Failure to do so can lead to emphasizing the wrong social, institutional, and environmental factors that enable conservation and underestimating conservation opportunities in landscapes where social norms or institutional constraints inhibit reporting. 

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3. House Price Index as an early indicator of development risk to biodiversity

   https://doi.org/10.1093/JUE/juae020  

   Acosta_Alamo, Marlen; Manne, Lisa L; Veit, Richard R (November 2024, Journal of Urban Ecology)

   Abstract Habitat loss due to changes in land cover is one of the main causes of biodiversity decline worldwide. Habitat loss occurs disproportionately in areas of high biodiversity because these same areas are particularly suitable for development. We assessed the effect of development risk on the biodiversity of breeding birds in the United States. We compared the effect of two predictors of habitat loss on the richness, abundance, and rarity of woodland, open-habitat, and urban birds at the local and regional levels. We used the House Price Index—as a measure of development risk—and primary productivity as predictors in simulations of habitat loss. For local scale analysis, we used generalized regression models. For regional-scale habitat loss simulations, we statistically compared the results obtained from each predictor. Locally, development risk and primary productivity interacted in their effect on the richness, abundance, and rarity index of all birds. At the regional level, developme 

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4. Exposure to climate change drives stability or collapse of desert mammal and bird communities

   https://doi.org/10.1126/science.abd4605  

   Riddell, E. A.; Iknayan, K. J.; Hargrove, L.; Tremor, S.; Patton, J. L.; Ramirez, R.; Wolf, B. O.; Beissinger, S. R. (February 2021, Science)

   High exposure to warming from climate change is expected to threaten biodiversity by pushing many species toward extinction. Such exposure is often assessed for all taxa at a location from climate projections, yet species have diverse strategies for buffering against temperature extremes. We compared changes in species occupancy and site-level richness of small mammal and bird communities in protected areas of the Mojave Desert using surveys spanning a century. Small mammal communities remained remarkably stable, whereas birds declined markedly in response to warming and drying. Simulations of heat flux identified different exposure to warming for birds and mammals, which we attribute to microhabitat use. Estimates from climate projections are unlikely to accurately reflect species’ exposure without accounting for the effects of microhabitat buffering on heat flux. 

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5. Weak but consistent abundance–occupancy relationships across taxa, space and time

   https://doi.org/10.1111/geb.13472  

   Ten Caten, Cleber; Holian, Lauren; Dallas, Tad (March 2022, Global Ecology and Biogeography)

   Abstract AimAbundance–occupancy relationships posit that more locally abundant species occupy more sites than less abundant species. Although widely supported, the occurrence and detection of abundance–occupancy relationships is sensitive to sampling and detection processes. Data from large‐scale standardized sampling efforts are key to address abundance–occupancy relationships. We aimed to use such a dataset to evaluate the occurrence of abundance–occupancy relationships across different spatial grains and over time for aquatic and terrestrial taxa. LocationUSA. Time period2014–2019. Major taxa studiedBirds, mammals, beetles, ticks, fishes, macroinvertebrates and zooplankton. MethodsSpecies abundance and occupancy data were obtained from the National Ecological Observatory Network (NEON). Species mean abundance and occupancy (fraction of sampled locations that were occupied) were estimated for three different spatial grains (i.e., plot, site and domain) for all years sampled. Linear models were used to explore the consistency of interspecific abundance–occupancy relationships. The slope coefficients of these models were related to temporal and spatial variables and to species richness while controlling for taxa in a linear mixed‐effects model (LMM) framework. ResultsWe found evidence for positive abundance–occupancy relationships across the three spatial grains and over time for all taxa we studied. However, our linear models had low explanatory power, suggesting that relationships, although general, were weak. Abundance–occupancy relationships were slightly stronger at the smallest spatial grain than at the largest spatial grain, but showed no detectable change over time for any taxa. Finally, species richness was not associated with the strength of these relationships. Main conclusionsTogether, our results suggest that positive interspecific abundance–occupancy relationships are fairly general but are not capable of explaining substantial variation in spatial patterns of abundance, and that other factors, such as species traits and niche, are also likely to influence these relationships. 

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