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Assessing invertebrate species for the IUCN Red List under Criterion A frequently involves fitting an appropriate statistical model to available abundance data and calculating a 10‐year change (TYC) estimate from predicted abundances. When the rate of change has not been constant across the entire time series, models that accommodate variable change rates are recommended.The monarch butterfly (Danaus plexippus) was recently added to the IUCN Red List (A2ab Endangered) based on analysis of data on winter abundances in Mexico and the western USA between 1993 and 2020. TYC estimates in the monarch assessment came from models that assumed constant change rates. We conducted a Bayesian analysis of the same data using models that accommodated variable change rates and used those models to compute TYC estimates.Our results suggested that monarch population change rates have not been constant over the study period. The analysis yielded a model‐averaged TYC estimate of +5.23%, which was not statistically distinguishable from 0% and was considerably different from values of −46% and −72% in the assessment. The Bayesian posterior probability of a TYC value below −30% (A2ab Vulnerable) was 0.15 and that of a TYC value below −50% (A2ab Endangered) was 0.03.We recommend that researchers evaluating monarch conservation status consider using abundance models with variable change rates, as models with constant change rates may not accurately predict the trajectory of monarch abundances into the future. [ABSTRACT FROM AUTHOR]

The conservation of migratory birds poses a fundamental challenge, their conservation requires coordinated action across the hemisphere, but those actions must be designed and implemented locally. To address this challenge, we describe a multilevel framework for linking broad‐scale, full annual cycle prioritizations to local conservation actions for migratory birds. We developed hemisphere‐scale spatial prioritizations for the full annual cycle of migratory birds that breed in six different ecosystems in North America. The full annual cycle prioritizations provide a hemispheric context within which regional priorities can be identified. Finer resolution, regional prioritizations can then inform local conservation actions more effectively. We describe the importance of local conservation practitioner contributions at each level of the process and provide two examples of regional spatial prioritizations that were developed to guide local action. The first example focused on coastal North and South Carolina, USA, and used information on marsh birds, shorebirds, ecological integrity, and co‐benefits for people to identify Cape Romain, South Carolina as a high‐priority site for conservation action. The second example in Colombia used information on migrant and resident birds to identify the Cauca Valley as a high‐priority site. The multilevel conceptual framework we describe is one pathway for identifying sites for implementation of local conservation actions that are guided by conservation priorities for migratory birds across their full annual cycle. [ABSTRACT FROM AUTHOR]

For many avian species, spatial migration patterns remain largely undescribed, especially across hemispheric extents. Recent advancements in tracking technologies and high‐resolution species distribution models (i.e., eBird Status and Trends products) provide new insights into migratory bird movements and offer a promising opportunity for integrating independent data sources to describe avian migration. Here, we present a three‐stage modeling framework for estimating spatial patterns of avian migration. First, we integrate tracking and band re‐encounter data to quantify migratory connectivity, defined as the relative proportions of individuals migrating between breeding and nonbreeding regions. Next, we use estimated connectivity proportions along with eBird occurrence probabilities to produce probabilistic least‐cost path (LCP) indices. In a final step, we use generalized additive mixed models (GAMMs) both to evaluate the ability of LCP indices to accurately predict (i.e., as a covariate) observed locations derived from tracking and band re‐encounter data sets versus pseudo‐absence locations during migratory periods and to create a fully integrated (i.e., eBird occurrence, LCP, and tracking/band re‐encounter data) spatial prediction index for mapping species‐specific seasonal migrations. To illustrate this approach, we apply this framework to describe seasonal migrations of 12 bird species across the Western Hemisphere during pre‐ and postbreeding migratory periods (i.e., spring and fall, respectively). We found that including LCP indices with eBird occurrence in GAMMs generally improved the ability to accurately predict observed migratory locations compared to models with eBird occurrence alone. Using three performance metrics, the eBird + LCP model demonstrated equivalent or superior fit relative to the eBird‐only model for 22 of 24 species–season GAMMs. In particular, the integrated index filled in spatial gaps for species with over‐water movements and those that migrated over land where there were few eBird sightings and, thus, low predictive ability of eBird occurrence probabilities (e.g., Amazonian rainforest in South America). This methodology of combining individual‐based seasonal movement data with temporally dynamic species distribution models provides a comprehensive approach to integrating multiple data types to describe broad‐scale spatial patterns of animal movement. Further development and customization of this approach will continue to advance knowledge about the full annual cycle and conservation of migratory birds. [ABSTRACT FROM AUTHOR]

Many insects are in clear decline, with monarch butterflies (Danaus plexippus) drawing particular attention as a flagship species. It is well documented that, among migratory populations, numbers of overwintering monarchs have been falling across several decades, but trends among breeding monarchs are less clear. Here, we compile >135,000 monarch observations between 1993 and 2018 from the North American Butterfly Association's annual butterfly count to examine spatiotemporal patterns and potential drivers of adult monarch relative abundance trends across the entire breeding range in eastern and western North America. While the data revealed declines at some sites, particularly the US Northeast and parts of the Midwest, numbers in other areas, notably the US Southeast and Northwest, were unchanged or increasing, yielding a slightly positive overall trend across the species range. Negative impacts of agricultural glyphosate use appeared to be counterbalanced by positive effects of annual temperature, particularly in the US Midwest. Overall, our results suggest that population growth in summer is compensating for losses during the winter and that changing environmental variables have offsetting effects on mortality and/or reproduction. We suggest that density‐dependent reproductive compensation when lower numbers arrive each spring is currently able to maintain relatively stable breeding monarch numbers. However, we caution against complacency since accelerating climate change may bring growing threats. In addition, increases of summer monarchs in some regions, especially in California and in the south, may reflect replacement of migratory with resident populations. Nonetheless, it is perhaps reassuring that ubiquitous downward trends in summer monarch abundance are not evident. [ABSTRACT FROM AUTHOR]

One of the most pressing questions in ecology and conservation centers on disentangling the relative impacts of concurrent global change drivers, climate and land‐use/land‐cover (LULC), on biodiversity. Yet studies that evaluate the effects of both drivers on species' winter distributions remain scarce, hampering our ability to develop full‐annual‐cycle conservation strategies. Additionally, understanding how groups of species differentially respond to climate versus LULC change is vital for efforts to enhance bird community resilience to future environmental change. We analyzed long‐term changes in winter occurrence of 89 species across nine bird groups over a 90‐year period within the eastern United States using Audubon Christmas Bird Count (CBC) data. We estimated variation in occurrence probability of each group as a function of spatial and temporal variation in winter climate (minimum temperature, cumulative precipitation) and LULC (proportion of group‐specific and anthropogenic habitats within CBC circle). We reveal that spatial variation in bird occurrence probability was consistently explained by climate across all nine species groups. Conversely, LULC change explained more than twice the temporal variation (i.e., decadal changes) in bird occurrence probability than climate change on average across groups. This pattern was largely driven by habitat‐constrained species (e.g., grassland birds, waterbirds), whereas decadal changes in occurrence probabilities of habitat‐unconstrained species (e.g., forest passerines, mixed habitat birds) were equally explained by both climate and LULC changes over the last century. We conclude that climate has generally governed the winter occurrence of avifauna in space and time, while LULC change has played a pivotal role in driving distributional dynamics of species with limited and declining habitat availability. Effective land management will be critical for improving species' resilience to climate change, especially during a season of relative resource scarcity and critical energetic trade‐offs. [ABSTRACT FROM AUTHOR]

Our novel method for evaluating the conservation efficacy of coastal and wetland protected areas showed that both stewardship sites and protected areas had more positive trends across a plurality or majority of species (five and seven, respectively) than unprotected sites. Therefore, the primary differentiating factor between stewardship sites and protected areas was that of known, consistently implemented stewardship and engagement activities specifically for coastal birds at the former site type versus unknown occurrence or absence of stewardship at protected or unprotected areas, similar to a background sample in species distribution modeling. Keywords: accountable conservation; coastal birds; community science; Gulf of Mexico; population trends; protected areas; áreas protegidas; aves costeras; ciencia comunitaria; conservación responsable; Golfo de México; tendencias poblacionales; ; ; ; ; ; EN accountable conservation coastal birds community science Gulf of Mexico population trends protected areas áreas protegidas aves costeras ciencia comunitaria conservación responsable Golfo de México tendencias poblacionales 1484 1495 12 10/05/21 20211001 NES 211001 Introduction Anthropogenic pressures including habitat loss, resource use, and human disturbance are key drivers of biodiversity declines (Murphy & Romanuk, 2014; Pereira et al., 2010). Two species also had more negative trends at protected areas compared with unprotected areas, whereas no species had more negative trends at stewardship sites than protected areas. [Extracted from the article]

Increasing concerns exist about possible decreased wintering duck abundance and hunting opportunities in the southern regions of the Atlantic and Mississippi flyways of North America. Researchers suggest these decreased abundances of ducks may be related to winter warming and related climatic phenomena. Accordingly, we tested predictions that duck abundance was increasing more at northern than southern latitudes, and that trends were related to average winter temperatures (Dec–Jan). We tested predictions using National Audubon Society Christmas Bird Count (CBC) data collected during December 1969 through January 2019 from 31 states in the United States and 6 Canadian provinces that comprise the Atlantic and Mississippi flyways for 16 species of dabbling and diving ducks (Anatinae). We found support for the prediction that CBC trends in duck abundance vary with latitude, and mean winter temperature explained nearly half the variation in CBC trends for 12 of 16 species. For some species, trends were negative in warmer regions and positive in colder regions. For others, trends were stable or slightly positive in warmer regions but more positive in colder regions. These results provide empirical evidence supporting climate‐influenced winter range changes by important game duck species and suggest challenges and opportunities for waterfowl population, habitat, and hunting management in North America and the northern hemisphere. © 2021 The Wildlife Society. : We analyzed 49 years of Christmas Bird Count and December–January temperature data (1970–2019) to test predictions that dabbling and diving duck abundances in the Atlantic and Mississippi flyways of North America were increasing more at northern than southern latitudes and trends were related to average winter temperatures. We found support for the prediction for 12 of 16 species. Our results provide empirical evidence supporting climate‐influenced winter range changes by important game duck species and suggest challenges and opportunities for waterfowl population, habitat, and hunting management in North America. [ABSTRACT FROM AUTHOR]

During animal migration, ephemeral communities of taxa at all trophic levels co‐occur over space and time. The interactions between predators and prey along migration corridors are ecologically and evolutionarily significant. However, these interactions remain understudied in terrestrial systems and warrant further investigations using novel approaches. We investigated the predator–prey interactions between a migrating avivorous predator and ephemeral avian prey community in the fall migration season. We tested for associations between avian traits and prey selection and hypothesized that prey traits (i.e. relative size, flocking behaviour, habitat, migration tendency and availability) would influence prey selection by a sexually dimorphic raptor on migration. To document prey consumption, we sampled trace prey DNA from beaks and talons of migrating sharp‐shinned hawks Accipiter striatus (n = 588). We determined prey availability in the ephemeral avian community by extracting weekly abundance indices from eBird Status and Trends data. We used discrete choice models to assess prey selection and visualized the frequency of prey in diet and availability on the landscape over the fall migration season. Using eDNA metabarcoding, we detected prey species on 94.1% of the hawks sampled (n = 525/588) comprising 1396 prey species detections from 65 prey species. Prey frequency in diet and eBird relative abundance of prey species were correlated over the migration season for top‐selected prey species, suggesting prey availability is an important component of raptor‐songbird interactions during fall. Prey size, flocking behaviour and non‐breeding habitat association were prey traits that significantly influenced predator choice. We found differences between female and male hawk prey selection, suggesting that sexual size dimorphism has led to distinct foraging strategies on migration. This research integrated field data collected by a volunteer‐powered raptor migration monitoring station and public‐generated data from eBird to reveal elusive predator–prey dynamics occurring in an ephemeral raptor‐songbird community during fall migration. Understanding dynamic raptor‐songbird interactions along migration routes remains a relatively unexplored frontier in animal ecology and is necessary for the conservation and management efforts of migratory and resident communities. [ABSTRACT FROM AUTHOR]

Tricolored blackbird (Agelaius tricolor) is a colonial breeder, largely restricted to grasslands, wetlands, and agricultural areas of California, USA. Tricolored blackbird abundance declined considerably during the twentieth century. Recent trends have been less clear, however, hindering efforts to evaluate the conservation needs of the species. We assessed trends in tricolored blackbird colony size using 2008, 2011, 2014, and 2017 Triennial Tricolored Blackbird Statewide Survey, a community‐science effort involving hundreds of volunteer observers. After accounting for variation in observer characteristics and survey effort, we found a clear, statistically significant decrease in average colony size of approximately 5% per year, which translated to a decrease in average colony size of approximately 40% between 2008 and 2017. This decrease in colony size matches the overall decline in abundance reported in another recent study and reinforces the conclusion that tricolored blackbird is in need of protection and recovery efforts. © 2019 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. We assessed trends in tricolored blackbird colony size using community science surveys, explicitly modeling variation in observer identity and effort, California, USA, 2008–2017. We documented a 5% annual decline in colony size, which translated to a 40% decline in colony size over the past decade. [ABSTRACT FROM AUTHOR]

Perennial bioenergy systems, such as switchgrass and restored prairies, are alternatives to commonly used annual monocultures such as maize. Perennial systems require lower chemical input, provide greater ecosystem services such as carbon storage, greenhouse gas mitigation and support greater biodiversity of beneficial insects. However, biomass harvest will be necessary in managing these perennial systems for bioenergy production, and it is unclear how repeated harvesting might affect ecosystem services., In this study, we examined how repeated production-scale harvesting of diverse perennial grasslands influences vegetation structure, natural enemy communities (arthropod predators and parasitoids), and natural biocontrol services in two states (Wisconsin and Michigan, USA) over multiple years., We found that repeated biomass harvest reduced litter biomass and increased bare ground cover. Some natural enemy groups, such as ground-dwelling arthropods, decreased in abundance with harvest, whereas others such as foliar-dwelling arthropods increased in abundance. The disparity in responses is likely due to how different taxonomic groups utilize vegetation and differences in dispersal abilities., At the community level, biomass harvest altered community composition, increased total arthropod abundance and decreased evenness but did not influence species richness, diversity or biocontrol services. Harvest effects varied with time, diminishing in strength both within the season (for total abundance and evenness), across seasons (for evenness) or were consistent throughout the duration of the study (for community composition). Greater functional redundancy and compensatory responses of the different taxonomic groups may have buffered against the potentially negative effects of harvest on biocontrol services., Synthesis and applications. Our results show that in the short-term, repeated harvesting of perennial grasslands (when insect activity is low) consistently altered vegetation structure but had mixed effects on natural enemy communities and no discernible effects on biocontrol services. However, the long-term effects of repeated harvesting on vegetation structure, natural enemies and other arthropod-derived ecosystem services such as pollination and decomposition remain largely unknown. [ABSTRACT FROM AUTHOR]

Noxious species, i.e., crop pest or invasive alien species, are major threats to both natural and managed ecosystems. Invasive pests are of special importance, and knowledge about their distribution and abundance is fundamental to minimize economic losses and prioritize management activities. Occurrence models are a common tool used to identify suitable zones and map priority areas (i.e., risk maps) for noxious species management, although they provide a simplified description of species dynamics (i.e., no indication on species density). An alternative is to use abundance models, but translating abundance data into risk maps is often challenging. Here, we describe a general framework for generating abundance-based risk maps using multi-year pest data. We used an extensive data set of 3968 records collected between 2003 and 2013 in Wisconsin during annual surveys of soybean aphid ( SBA), an exotic invasive pest in this region. By using an integrative approach, we modelled SBA responses to weather, seasonal, and habitat variability using generalized additive models ( GAMs). Our models showed good to excellent performance in predicting SBA occurrence and abundance ( TSS = 0.70, AUC = 0.92; R2 = 0.63). We found that temperature, precipitation, and growing degree days were the main drivers of SBA trends. In addition, a significant positive relationship between SBA abundance and the availability of overwintering habitats was observed. Our models showed aphid populations were also sensitive to thresholds associated with high and low temperatures, likely related to physiological tolerances of the insects. Finally, the resulting aphid predictions were integrated using a spatial prioritization algorithm ('Zonation') to produce an abundance-based risk map for the state of Wisconsin that emphasized the spatiotemporal consistency and magnitude of past infestation patterns. This abundance-based risk map can provide information on potential foci of pest outbreaks where scouting efforts and prophylactic measures should be concentrated. The approach we took is general, relatively simple, and can be applied to other species, habitats and geographical areas for which species abundance data and biotic and abiotic data are available. [ABSTRACT FROM AUTHOR]

Increases in natural or noncrop habitat surrounding agricultural fields have been shown to be correlated with declines in insect crop pests. However, these patterns are highly variable across studies suggesting other important factors, such as abiotic drivers, which are rarely included in landscape models, may also contribute to variability in insect population abundance. The objective of this study was to explicitly account for the contribution of temperature and precipitation, in addition to landscape composition, on the abundance of a widespread insect crop pest, the soybean aphid ( Aphis glycines Matsumura), in Wisconsin soybean fields. We hypothesized that higher soybean aphid abundance would be associated with higher heat accumulation (e.g., growing degree days) and increasing noncrop habitat in the surrounding landscape, due to the presence of the overwintering primary hosts of soybean aphid. To evaluate these hypotheses, we used an ecoinformatics approach that relied on a large dataset collected across Wisconsin over a 9-year period (2003-2011), for an average of 235 sites per year ( n = 2,110 fields total). We determined surrounding landscape composition (1.5-km radius) using publicly available satellite-derived land cover imagery and interpolated daily temperature and precipitation information from the National Weather Service COOP weather station network. We constructed linear mixed models for soybean aphid abundance based on abiotic and landscape explanatory variables and applied model averaging for prediction using an information theoretic framework. Over this broad spatial and temporal extent in Wisconsin, we found that variation in growing season precipitation was positively related to soybean aphid abundance, while higher precipitation during the nongrowing season had a negative effect on aphid populations. Additionally, we found that aphid populations were higher in areas with proportionally more forest but were lower in areas where minor crops, such as small grains, were more prevalent. Thus, our findings support our hypothesis that including abiotic drivers increases our understanding of crop pest abundance and distribution. Moreover, by explicitly modeling abiotic factors, we may be able to explore how variable climate in tandem with land cover patterns may affect current and future insect populations, with potentially critical implications for crop yields and agricultural food webs. [ABSTRACT FROM AUTHOR]

Increased demand and government mandates for bioenergy crops in the United States could require a large allocation of agricultural land to bioenergy feedstock production and substantially alter current landscape patterns. Incorporating bioenergy landscape design into land-use decision making could help maximize benefits and minimize trade-offs among alternative land uses. We developed spatially explicit landscape scenarios of increased bioenergy crop production in an 80-km radius agricultural landscape centered on a potential biomass-processing energy facility and evaluated the consequences of each scenario for bird communities. Our scenarios included conversion of existing annual row crops to perennial bioenergy grasslands and conversion of existing grasslands to annual bioenergy row crops. The scenarios explored combinations of four biomass crop types (three potential grassland crops along a gradient of plant diversity and one annual row crop [corn]), three land conversion percentages to bioenergy crops (10%, 20%, or 30% of row crops or grasslands), and three spatial configurations of biomass crop fields (random, clustered near similar field types, or centered on the processing plant), yielding 36 scenarios. For each scenario, we predicted the impact on four bird community metrics: species richness, total bird density, species of greatest conservation need (SGCN) density, and SGCN hotspots (SGCN birds/ha ≥ 2). Bird community metrics consistently increased with conversion of row crops to bioenergy grasslands and consistently decreased with conversion of grasslands to bioenergy row crops. Spatial arrangement of bioenergy fields had strong effects on the bird community and in some cases was more influential than the amount converted to bioenergy crops. Clustering grasslands had a stronger positive influence on the bird community than locating grasslands near the central plant or at random. Expansion of bioenergy grasslands onto marginal agricultural lands will likely benefit grassland bird populations, and bioenergy landscapes could be designed to maximize biodiversity benefits while meeting targets for biomass production. [ABSTRACT FROM AUTHOR]

The strength and prevalence of trophic cascades, defined as positive, indirect effects of natural enemies (predatory and parasitic arthropods) on plants, is highly variable in agroecosystems. This variation may in part be due to the spatial or landscape context in which these trophic cascades occur. In 2011 and 2012, we conducted a natural enemy exclusion experiment in soybean fields along a gradient of landscape composition across southern Wisconsin and Michigan, USA. We used structural equation modeling to ask (1) whether natural enemies influence biocontrol of soybean aphids (SBA) and soybean yield and (2) whether landscape effects on natural enemies influence the strength of the trophic cascades. We found that natural enemies (NE) suppressed aphid populations in both years of our study, and, in 2011, the yield of soybean plants exposed to natural enemies was 37% higher than the yield of plants with aphid populations protected from natural enemies. The strength of the trophic cascade was also influenced by landscape context. We found that landscapes with a higher proportion of soybean and higher diversity habitats resulted in more NE, fewer aphids, and, in some cases, a trend toward greater soybean yield. These results indicate that landscape context is important for understanding spatial variability in biocontrol and yield, but other factors, such as environmental variability and compensatory growth, might overwhelm the beneficial effects of biocontrol on crop yield. [ABSTRACT FROM AUTHOR]

Anthropogenic changes in atmospheric carbon dioxide ( CO2) and ozone (O3) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood., We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 ( c. 560 ppm) and O3 ( c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments., Leaf-chewing herbivores fluxed 6.2 g m−2 yr−1 of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3. Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs., Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments. [ABSTRACT FROM AUTHOR]

We examined the potential local- and landscape-level impacts of different biofuel production systems on biocontrol, an important service provided by arthropod natural enemies. Specifically, we sampled natural enemies with sweep nets and measured predation of sentinel pest eggs in stands of corn, switchgrass and mixed prairie in Michigan and Wisconsin (total n=40 for natural enemy sampling, n=60 for egg predation), relating them to crop type, forb cover and diversity, and the composition and heterogeneity of the surrounding landscape. Grasslands with intermediate levels of forb cover and flower diversity supported two-orders of magnitude more natural enemy biomass, fourfold more natural enemy families, and threefold greater rates of egg predation than corn. Data suggest this was in part due to a general increase in biomass, richness and predation in perennial grasslands compared with corn, combined with a positive effect of intermediate levels of forb cover and flower diversity. Specifically, natural enemy biomass and family richness showed hump-shaped relationships to forb cover that peaked in sites with 5-25% forbs, while egg predation increased with floral diversity. At the landscape scale, both natural-enemy biomass and egg predation increased with the area of forest in the landscape, and egg predation almost doubled as the area of herbaceous, perennial habitats within 1.5 km of study sites increased. Our results suggest that floristically diverse, perennial grasslands support diverse and abundant predator communities that contribute to natural pest suppression. In addition, large-scale production of biofuel crops could positively or negatively affect biocontrol services in agricultural landscapes through associated changes in the area of perennial habitats. Biofuel landscapes that incorporate perennial grasslands could support a variety of beneficial organisms and ecosystem services in addition to producing biomass. [ABSTRACT FROM AUTHOR]

According to the energetic equivalence rule, energy use by a population is independent of average adult body mass. Energy use can be equated with carbon flux, and it has been suggested that population fluxes of other materials, such as nitrogen and phosphorus, might also be independent of body mass. We compiled data on individual nitrogen deposition rates (via faeces and urine) and average population densities of 26 species of mammalian herbivores to test the hypothesis of elemental equivalence for nitrogen. We found that the mass scaling of individual nitrogen flux was opposite to that of population density for the species in our dataset. By computing the product of individual nitrogen flux and average population density for each species in our dataset, we found that population-level nitrogen flux was independent of species mass, averaging c. 3.22 g N ha−1 day−1. Results from this analysis can be used to understand the influence of mammalian herbivore communities on nitrogen cycling in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Tools from metabolic scaling and food web theory were used to construct a general model of carbon flux by litter and soil invertebrates. The flux model was used to explore the energetic basis of invertebrate abundance and predicted that abundance should (1) scale linearly with net primary production: (2) be related to the body mass of animals as a power function, with an exponent between -0.65 and -0.85; (3) be related to the average body temperature of animals according to the Boltzmann factor, with an activation energy between 0.27 and 0.79 eV; and (4) decrease by a factor of 0.05 to 0.15 across trophic levels due to gross production efficiency of prey, Model predictions were generally supported by a global data set on invertebrate abundance that was amassed during the International Biological Programme, indicating that fundamental energetic principles explain a large degree of variation in invertebrate abundance across the globe. [ABSTRACT FROM AUTHOR]

There is increasing evidence that individual energetics constrain macroecological patterns. Here we model total abundance within winter landbird communities as a function of (1) energy supply, as measured by ecosystem net primary productivity, and (2) energy use of individuals, as influenced by body mass and ambient temperature. Using data from the North American Christmas Bird Count, we find that total abundance increases with productivity to the 0.61 power, and decreases with body mass and environmental temperature as predicted by metabolic theory when individuals are below their thermoneutral zone. We note a negative relationship between ambient temperature and average body mass, and suggest that this community-level pattern, reminiscent of Bergmann's Rule, is related to a tendency for small species to be less-abundant or absent from cold locations. Results from this study emphasize the importance of individual-level metabolism for understanding large-scale ecological patterns. [ABSTRACT FROM AUTHOR]

Intraspecific migration patterns in birds have both spatial and temporal components. Two commonly reported spatial patterns are leap-frog and chain migration. Temporal migration patterns refer to the timing of migration of populations from different breeding latitudes. We investigated the spatial and temporal migration patterns of hatching-year (HY) sharp-shinned hawks Accipiter striatus of interior North America using stable-hydrogen isotope and band encounter analyses. Feather samples were collected from hawks migrating through New Mexico, USA and measured for their stable-hydrogen isotope ratios (δD) to distinguish individuals originating from relatively high and low natal latitudes. We then examined the relationship between feather δD values and passage dates through New Mexico, USA. We also gathered band encounter data from the Bird Banding Lab of the United States Geological Survey to determine the wintering latitudes of HY sharp-shinned hawks relative to their passage date through migration banding sites in interior North America. Combining these data, we found that during fall migration HY sharp-shinned hawks used a chain migration pattern, that is, hawks originating from lower latitudes wintered further south than those from higher latitudes. In addition, birds originating from lower latitudes passed through interior North America earlier than those from higher latitudes. We also found that hawks from higher latitudes were significantly larger than those from lower latitudes, and that females from higher latitudes had significantly higher estimated fat levels than females from lower latitudes. [ABSTRACT FROM AUTHOR]

Objectives: Thermoregulation by modern industrial humans is unique among endothermic animals, in that it is largely accomplished by controlling the temperature of our external environment. The objective of this study was to view the relationship between thermoregulatory energy use and environmental temperature in modern humans from the perspective of comparative physiology. Methods: Monthly residential energy use estimates from the US Energy Information Administration were divided by the annual number of American households from the US Census Bureau, giving average monthly energy consumption per American household for the years 2006 through 2010. Monthly energy consumption was then plotted against average monthly temperature across the United States from the National Climatic Data Center. Results: The resulting graph bore a striking resemblance to a classic Scholander-Irving curve, exhibiting clear upper (22°C) and lower (15°C) critical temperatures, and an increase in energy use as temperatures extend above (90 W °C−1 increase) or below (244 W °C−1 decrease) those critical temperatures. Allometric equations from comparative physiology indicate that the energetic costs of our current thermoregulatory habits are ∼30 to 50 times those predicted for an endotherm of our size. Conclusions: Modern humans have redefined what it means to be a homeothermic endotherm, using large quantities of extrametabolic energy to regulate the temperature of our surroundings. Despite this sophistication, the signal of our individual physiology is readily discernible in national data on energy consumption. Am. J. Hum. Biol., 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Bird counts by community volunteers provide valuable information about the conservation needs of many bird species. The statistical modeling techniques commonly used to analyze these counts provide robust, long‐term population trend estimates from heterogeneous community science data at regional, national, and continental scales. Here, we present a new modeling approach that increases the spatial resolution of trend estimates and reduces the computational burden of trend estimation, each by an order of magnitude. We demonstrate the approach with data for the American Robin (Turdus migratorius) from Audubon Christmas Bird Counts conducted between 1966 and 2017. We show that aggregate regional trend estimates from the proposed method aligned well with those from the current standard method, and that spatial variation in trends was associated with winter temperatures and human population densities as predicted by ecological energetics. This technique can provide reasonable large‐scale trend estimates for users interested in general patterns, while also providing higher‐resolution estimates for examining correlates of abundance trends at finer spatial scales, which is a prerequisite for tailoring management plans to local conditions. [ABSTRACT FROM AUTHOR]