Cities are the planet's newest ecosystem and thus provide the opportunity to study community formation directly following major permanent environmental change. The human social and built components ...of environments can vary widely in different cities, yet it is largely unknown how features of cities covary with the traits of colonizing species despite humans being the ultimate cause of environments and disturbances in cities. We constructed a dataset from open‐source data comprised of 13,502 breeding season observations of 213 passerine species observed in 551 Census‐defined urban areas across the United States. We found that as a city became more compact with less sprawl it tended to support more migratory species and species with lower body mass, shorter lifespans, and larger clutches. We also found that species had lower body mass in cities with higher median income, and higher body mass in highly populated cities. Our results highlight the complexity of human‐dominated urban ecosystems, where human socioeconomic actions and everyday activities intermix leading to structurally heterogeneous environments that support the colonization of some species over others.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The coccidian parasite Toxoplasma gondii is found worldwide infecting warm-blooded vertebrates. Felids are the definitive hosts; other species act as intermediate hosts. Squirrels (Sciuridae) ...generally have high population densities in cities and forage and cache food on the ground, where they may come into contact with T. gondii oocysts or be preyed upon by cats and other carnivores. This environment might make squirrels important intermediate hosts of T. gondii in cities, and infection rates could indicate environmental levels of oocysts in soil. We investigated whether urban squirrels would be more exposed to T. gondii infection than rural squirrels with samples collected from American red squirrels (Tamiasciurus hudsonicus), eastern grey squirrels (Sciurus carolinensis), northern flying squirrels (Glaucomys sabrinus), and least chipmunks (Tamias minimus) in and around Winnipeg, Manitoba, Canada. We tested 230 tissue samples from 46 squirrels for T. gondii DNA by quantitative PCR and 13 serum samples from grey squirrels for T. gondii antibodies by competitive ELISA. We found no evidence of infection in any squirrel, indicating that squirrels are probably not important intermediate hosts of T. gondii in cities and that consumption of oocysts in the soil in general may not be an important contributor to transmission in colder environments.
Cities are aggregates of human activities where our decisions shape the environment creating heterogeneity across urban centers that can have significant ecological effects on wildlife. Many bird ...species are found in cities during the breeding season, which implies they find sufficient resources in cities to support them during this energetically costly time. As populations of many migratory bird species are declining, knowledge of how they are affected by urbanization is needed. Yet, we know little about how the species richness of migratory birds varies across different types of cities. Here we ask if cities' structural and socioeconomic features can predict the species richness of migratory birds that generally select different breeding habitats during the breeding season. We used eBird data from census‐designated urban areas in the US to model the relationship between features of cities (housing density, median income, city age, and commuting time), environmental disturbance (measured by the human footprint index) and species richness by fitting generalized linear models to data. We show that commuting time was the most important factor determining species richness across cities and the rest of the city features were weakly associated with species richness. Overall species were responding to city variation in similar ways. While we expected that cities with more disturbance would have lower species richness, our results indicate that some species are able to tolerate even highly disturbed cities and that cities in certain regions may act as a refuge to birds. This knowledge is important for our general understanding of cities as habitat for birds and how migratory birds respond to across‐city variation during the breeding season.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Urban wildlife populations experience human-driven environmental changes that can be both beneficial and detrimental to individual health. We measured body condition and serum chemistry (electrolyte ...levels, markers of kidney and liver function, protein, glucose, and cholesterol) in a native urban and rural population of Eastern Gray Squirrel (Sciurus carolinensis) to assess whether we could detect physiological responses to environmental stressors or dietary differences. We found no differences in body condition between habitats and no evidence of malnutrition at either site. However, urban squirrels had higher blood glucose, lower potassium, phosphorus, chloride, and albumin:globulin ratios. These results align with previous findings of increased dietary sugar in cities and suggest that urban populations of gray squirrels are under greater environmental stress than rural populations, providing future directions for studying physiological responses to urbanization.
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