As human populations increase and city borders grow, many animals have to modify foraging behaviors in order to exploit evolutionarily novel urban food sources that could aid their survival. Neophobia, the fear of novelty, can lead to missed opportunities in these cases. Here, we studied the novelty response of wild animals in ecologically relevant conditions while controlling for individual characteristics and potential differences in foraging group size. We predicted that urban black-capped chickadees (Poecile atricapillus) would be more likely to initially contact novelty than rural chickadees and that subordinates and juveniles would be more likely to first contact novelty than dominants and adults, respectively. We ran replicated experiments using three novelty types (object, color, or food) on six sites, during which we registered feeder choice of 71 tagged individuals. We found that urban chickadees showed less neophobia than their rural counterparts, the latter having a higher probability of initially contacting the familiar feeder before approaching the novel feeder. There was no significant effect of an individual’s dominance, age, or sex on its first choice of feeder, nor was there any effect of novelty type. Overall, our results suggest that urban chickadees exhibit less neophobia than their rural counterparts because they have generally learned to tolerate novelty in their habitat, they have adapted to live in an environment that rewards low neophobia, and/or they are less reluctant to use feeders at new locations.

Weather often plays a key role in migration timing, and temporal shifts over the past century have been heavily researched and linked to climate change. Much research is however limited by the use of arbitrary time periods during which weather is thought to most influence migration. Here, we compare the classic fixed window method to a novel sliding window approach created to determine periods of temperature sensitivity among organisms, in this case on the migration phenology of nineteen passerine species banded at the McGill Bird Observatory in Montréal, Québec, from 2005 to 2015. We found overall shorter temperature sensitivity windows in the spring than the fall migration and deemed the nonarbitrarily chosen periods of temperature sensitivity to be more useful than the classic fixed window method when used with caution. We also found significant variation in migration timing of 11 species, as well as more cases of male birds arriving in spring prior to females than the reverse. More males departed in fall before females as well. Similarly, on average, older birds arrived in spring ahead of younger individuals and departed prior to younger in the fall.

Urbanization has a tremendous impact on the environment from landscape features to distribution of food resources. Such drastic environmental changes can result in community, population, and individual differences between urban and non-urban animals. Urbanization has been associated with differential mortality and reproduction and therefore, differences in age structure may also be expected across urban gradients. Additionally, many traits studied along urban gradients, such as morphology, can also differ across age classes, and as such, age is an important factor to consider. Despite this, differences in age structure along urbanization gradients have only rarely been examined. Here, we use black-capped chickadee (Poecile atricapillus) age, morphological, and feeder visitation data to address whether age structure, morphology, and age-related winter survival differ across a gradient of urban land use in and around Ottawa, ON. We test the hypothesis that urbanization is associated with higher proportions of juveniles, because of an increased exploratory tendency by juveniles against the hypothesis that urbanization favors higher proportions of adults because of a slower pace of life. We further hypothesize that urban chickadees will be smaller than nonurban ones, because anthropogenic environments will attract both younger and worse quality individuals. We found that urban environments were associated with significantly higher proportions of first year individuals and these proportions remained stable from late fall through all of winter. We did not, however, find evidence that age related differences explained variation in morphology. Instead variation in morphology was small and inconsistently associated with both urbanization and age. The results stand in contrast to results for two species of European birds. The present study calls for using broadly available but under-exploited data to better understand urbanization-related differences in age structure and its implications for populationlevel processes such as disease transmission and information flow.