Effects of urbanization on bird migration

Abstract

Nearly one in five bird species is migratory, but not all individuals within a migratory species necessarily migrate: in partially migratory species, some do and some do not. Such within-species variability provides a natural experiment for investigating the mechanisms driving bird migration. Previous studies at the species level suggest that migrating provides a way to escape harsh winters, and to secure an increased access to resources, particularly important during the breeding season. Urbanization, by altering local temperatures ('heat island' effect) and resource availability (e.g. through garbage or garden feeders) can buffer the effects of winter harshness and modify breedingseason resource availability, potentially affecting individual migratory strategies. Here, we use ringing data from twelve North American partially migratory bird species to investigate the effects of natural environmental conditions (winter temperature, breeding season resource surplus) and urbanization on the propensity of individuals to migrate. We find strong support for the hypothesis that individuals migrate to avoid harsh winters, with, for eleven species, significantly higher probabilities of residency in areas with milder winters. We also found (significant for five species) that resource surplus in the breeding season reduces the propensity to migrate. Finally, urbanization increased the likelihood that individuals remain year-round in their ranges, avoiding to migrate away from their breeding range (four species) or their wintering areas (eight species), after controlling for climate and resources. Our results thus indicate that bird migratory strategies will respond to global changein climate and land useand indeed are already doing so.

The macroecology and evolution of avian competence forBorrelia burgdorferi

“…If such species become resident where ticks are abundant, sedentary behavior could increase vector exposure and amplify bird-tick transmission. Similarly, several Bbsl-competent birds (e.g., Sylvia atricapilla, Junco hyemalis) and unsampled but likely reservoirs (e.g., Spinus tristis) have shortened migration or become resident in cities (Yeh & Price, 2004;Plummer et al, 2015;Bonnet-Lebrun et al, 2020). This urban residency could increase or decrease competence depending on factors such as food availability and artificial light at night (Becker et al, 2019b;Kernbach et al, 2019).…”

Exploring intraspecific variation in migratory destinations to investigate the drivers of migration

“…First, there can be other sources of resources not captured by a remote sensing measure of greenness, such as some anthropogenic resources (e.g. bird feeders in gardens, Job and Bednekoff 2011, Bonnet‐Lebrun et al 2020a). In addition, the amount of food items specific to the diet of some species (e.g.…”

“…Additionally, the lack of perfect match between the virtual predicted ranges and the empirical ones suggest that additional drivers, such as habitat (Barnagaud et al 2012), including urban areas (Bonnet‐Lebrun et al 2020a) are likely to play a role. The variable quality of the match across species suggests that the nature and strength of these additional drivers are likely to be species‐dependent.…”

“…For some of these species, some populations are partially migratory (i.e. some individuals migrate and some do not; Bonnet‐Lebrun et al 2020a). As our aim was to understand migratory destinations, we focused on migratory individuals only, defined as those moving further than 50 km between seasonal locations (thus excluding resident individuals; Table 1).…”

Fruit and berry plants of forest belts as a factor of species diversity of ornithofauna during the breeding season and autumn migration period

“…Bird responses to powerful ground-based artificial light sources at night in urban areas have been studied (Doren et al, 2017;Sorteet et al, 2017;Smallwood & Bell, 2020). Urbanization increases the likelihood of feed-provided birds reducing their migration activity (Bonnet-Lebrun et al, 2020). The main biological mechanism regulating seasonal variation in migration rate is the seasonal difference in the duration of migration stops.…”