Are Bird Habitat Associations Consistent Across Space and Time?

The concept of the fundamental niche is frequently used in ecology to define the set of environmental conditions needed by a species to survive and reproduce (Hutchinson 1957). In contrast, the realized niche constitutes the locations where a species actually occurred, which is a function of both the environmental (abiotic) conditions and biotic interactions (e.g., predation, competition, mutualisms; Soberon and Peterson 2005). Up to now, the realized niche of most species has been mostly examined during breeding seasons and researchers have long assumed that niches should remain constant across species’ ranges and across the avian annual cycle. If this assumption is valid, then the conservation of each species across their full annual cycle is made easier because each species is associated with a single niche. However, if species have more than one realized niche, then we risk misleading conservation efforts by protecting the wrong habitat in some regions or seasons. In this dissertation, I aim to identify whether most species exhibit a single realized niche, or rather, that species have multiple niches that change depending on age and sex (Ch.2), geographic location (Ch. 3) or the stage of the annual cycle (Ch.4). More specifically, in chapter 2, I assembled a large dataset representing the capture (and release) of Rufous Hummingbirds (Selasphorus rufus) and calculated migration routes and timing across age and sex categories. The data showed that adult males, adult females and juveniles tend to migrate using different migration corridors. A greater number of young birds migrated south through California in comparison to the adults which migrated largely through the Rocky Mountain states. Moreover, migration timing also varied across age and sex categories with adult males departing first and young of both sexes departing last – on average one month after the adult males. Overall, the results of this chapter suggest that Rufous Hummingbirds likely encounter and use slightly different sets of environmental conditions during their fall migration across demographic groups. The goal of chapter 3 was to determine if species exhibit consistent habitat relationships across their breeding range. In other words, are niches sufficiently predictable that predictive models can be readily transferred from one location to another? This property is termed “stationarity”. I used Breeding Bird Survey data from across North America, land cover and climate data from remote sensing, and a model transferability methodology to predict avian abundance across space for 131 species. I also assessed whether species’ traits were correlated with levels of stationarity in distributions. Lastly, I tested whether prediction accuracies between modeled regions decreased with 1) geographical distances, 2) level of extrapolation, and 3) were affected by a ‘core-boundary’ effect. The results suggest that, for most species, habitat relationships change across species’ breeding ranges. Species with large distributions, with distributions in regions with less topographic relief, and species with shorter life spans were more likely to have non-stationary distributions. Moreover, results show that predicting across long geographical distances or to novel environments decreases prediction accuracies. Overall, these results suggest that caution should be used when assuming stationarity in models, because the habitat used by birds across regions sometimes differed in measurable ways within a species’ range. These results are important for conservation planning because many conservation efforts such as forecasts of biological invasions, prioritization of land protection, and translocation of endangered species relies on accurately predicting abundance across space (Guisan et al. 2013). Lastly, in chapter 4, I tested whether 83 migratory bird species are consistent in their niches throughout the annual cycle. Here, I used year-round data from the citizen science program, eBird, along with land cover and weather data from remote-sensing sources to calculate niches for each species in four different seasons in each year (2005 – 2020). I compared niches across years (within season) and across seasons (within years) and calculated the percent niche overlap and the drivers of niche dynamics between pairs of niches. As expected, niche overlap was higher across years than across seasons. Consistent with the niche plasticity hypothesis, the niches of migratory birds were largely stable across species’ annual life cycles, but with some small and significant differences among them. These results suggest that migrants have the most similar niches between spring and fall migrations, and most different niches between breeding and over-wintering grounds. Moreover, migratory birds seem to have the most constrained niches during the breeding season. These results suggest that while most migratory birds may rely on common sets of environmental conditions across seasons, the seasonal niches also contracted and expanded significantly throughout the year. Taken all together, the results of these three chapters suggest that each bird species is associated with differing sets of environmental conditions among demographic groups, and across space and time. As such, species are better represented by multiple realized niches, which overlap to different degrees within their fundamental niche. These results highlight the need to identify each species’ collection of realized niches in order to successfully conserve their populations and protect their habitat throughout their full life cycle. Doing so is likely essential to reversing the negative trends observed in our bird populations (Rosenberg et al. 2019)

Forest degradation drives widespread avian habitat and population declines

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has caused bird-population declines. Despite little change in overall forest cover, we found substantial reductions in old forest as a result of frequent clear-cutting and a broad-scale transformation to intensified forestry. Back-cast species distribution models revealed that breeding habitat loss occurred for 66% of the 54 most common species from 1985 to 2020 and was strongly associated with reduction in old age classes. Using a long-term, independent dataset, we found that habitat amount predicted population size for 94% of species, and habitat loss was associated with population declines for old-forest species. Forest degradation may therefore be a primary cause of biodiversity decline in managed forest landscapes

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Using continental-scale bird banding data to estimate demographic migratory patterns for Rufous Hummingbird (Selasphorus rufus)

The effective conservation of birds requires knowledge of species-specific population dynamics. Yet these dynamics during migration and across age and sex categories are poorly understood for small birds. The goal of this study was to assess large-scale fall migration patterns of Rufous Hummingbirds (Selasphorus rufus). Because the age and sex categories of this species depart from the breeding grounds and arrive from migration on different weeks, we predicted that each might use different migration routes, differ in migration speeds, and vary in their weekly distributions. Rufous Hummingbirds are among a few declining species for which a large amount of banding data is available during migration and across the migration corridor. We assembled a large hummingbird capture dataset (28,948 captures; 459 unique locations; fall migrations from 1998 to 2013) and used the centroid location of each age-sex-year-week group to calculate migration routes, timing, and speed. We used a utilization distribution kernel to measure distributions during migration. Adult females tended to have a southbound migration route parallel and between those of young and adult males. Moreover, a greater number of young birds migrated south through California in comparison to adult females and adult males. Our results suggest that the migration of each age-sex category is separated by approximately two weeks with adult males migrating first, followed by adult females, and then the young of both sexes; yet migration speed was not statistically different among categories. Last, adult males were captured within a smaller geographic distribution, i.e., the area during any given week of migration, compared with adult females and young. We conclude that different age-sex categories of Rufous Hummingbirds use alternative routes and differ in migration phenology and distributions. Our results suggest that the age-sex categories could be affected differentially by habitat loss, phenological changes, and climates during migration. Considering such demographic migratory dynamics could improve conservation outcomes

Advancing bee conservation in the US:gaps and opportunities in data collection and reporting

Introduction: Bee conservation in the US is currently hindered by challenges associated with assessing the status and trends of a diverse group of &gt;3000 species, many of which are rare, endemic to small areas, and/or exhibit high inter-annual variationin population size. Fundamental information about the distribution of most species across space and time, thus, is lacking yet urgently needed to assess population status, guide conservation plans, and prioritize actions among species and geographies. Methods: Using wild bee data from two public data repositories representing the contiguous US, we evaluated the availability and sufficiency of data for use in species assessments of wild bees. We also examined the number of bee species recorded in each US state and the proportion of species with recent records (2012–2021). Results: Although efforts to monitor bees continue to grow, there remains a massive paucity of data. Exceedingly few records (0.04%)reported both sampling protocol and effort, greatly limiting the usefulness of the data. Few species or locations have adequate publicly available data to support analyses of population status or trends, and fewer than half of species have sufficient data to delineate geographic range. Despite an exponential increase in data submissions since the 2000s, only 47% of species were reported within the last decade, which may be driven by how data are collected, reported, and shared, or may reflect troubling patterns of local or large-scale declines and extirpations. Discussion: Based on our analysis, we provide recommendations to improve the quality and quantity of data that can be used to detect, understand, and respond to changes in wild bee populations.</p

Advancing bee conservation in the US:gaps and opportunities in data collection and reporting

Introduction: Bee conservation in the US is currently hindered by challenges associated with assessing the status and trends of a diverse group of &gt;3000 species, many of which are rare, endemic to small areas, and/or exhibit high inter-annual variationin population size. Fundamental information about the distribution of most species across space and time, thus, is lacking yet urgently needed to assess population status, guide conservation plans, and prioritize actions among species and geographies.Methods: Using wild bee data from two public data repositories representing the contiguous US, we evaluated the availability and sufficiency of data for use in species assessments of wild bees. We also examined the number of bee species recorded in each US state and the proportion of species with recent records (2012–2021).Results: Although efforts to monitor bees continue to grow, there remains a massive paucity of data. Exceedingly few records (0.04%)reported both sampling protocol and effort, greatly limiting the usefulness of the data. Few species or locations have adequate publicly available data to support analyses of population status or trends, and fewer than half of species have sufficient data to delineate geographic range. Despite an exponential increase in data submissions since the 2000s, only 47% of species were reported within the last decade, which may be driven by how data are collected, reported, and shared, or may reflect troubling patterns of local or large-scale declines and extirpations.Discussion: Based on our analysis, we provide recommendations to improve the quality and quantity of data that can be used to detect, understand, and respond to changes in wild bee populations

Spectacular foodscapes: food celebrities and the politics of lifestyle mediation in an age of inequality

This editorial introduces a special issue of Food, Culture & Society and works to add a parallel, substantive take on the phenomenon of the food celebrity and the mediated, everyday cultural politics they create. We start by exploring the concept of the foodscape. Specifically, we argue that food celebrities represent a fundamental component of contemporary foodscapes, how they “perform” and function, and the socio-material means by which they are produced. We then explore the key roles and privileges of food celebrity, arguing that the celebrity chef is not the only high-profile, mediating figure at work on the foodscape. Key food celebrity paradoxes are identified and discussed: food celebrities must work to be authentic and aspirational, accessible yet exclusive, responsibilizing but also empowering. We conclude with a short contextualization of the papers in this special issue, and argue for the rich potential of food celebrity scholarship as a way to better understand food inequalitie