Contrasting Responses to Predation Risk in Urban and Non-Urban Rodents
Start Date
3-16-2026 4:00 PM
End Date
3-16-2026 6:00 PM
Abstract
Urbanization exposes animals to novel and often extreme conditions, with important consequences for species’ ability to persist in or invade urban environments. For example, urban environments frequently alter predator communities, exposing prey to novel predators or predator abundances. Increasing attention has focused on traits that promote urban tolerance or success (“ideal urban dweller” hypothesis). Among these traits, risk-taking behavior is thought to be especially important, as it shapes responses to altered predation risk and human cohabitation. Despite this interest, recent meta-analyses indicate that the literature is heavily biased toward avian systems, leaving other taxa, including nocturnal mammals, underrepresented. To address these gaps, we compared brown rats (Rattus norvegicus), a highly commensal, urban-dwelling species, with western deer mouse (Peromyscus sonoriensis), a native, non-urban species. Brown rats rely heavily on humans for resources such as food and shelter, traits that have likely facilitated their global urban invasion, whereas deer mice rarely occur in urban environments. We will identify rat and mouse populations on Lewis & Clark College campus and adjacent forest using camera traps, then assess each population’s response to perceived predation risk through two experiments: 1) measuring giving-up density (GUD) in exposed vs sheltered environments; and 2) a predator manipulation experiment using owl call playbacks. We will complement these data with an observational study relating owl presence (verified via camera traps and acoustic recordings) to rodent activity. Together, these data will allow us to test whether species with differing urban tolerance exhibit fundamentally different behavioral responses consistent with adaptation to urban environments.
Subjects
Animal ecology
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Contrasting Responses to Predation Risk in Urban and Non-Urban Rodents
Urbanization exposes animals to novel and often extreme conditions, with important consequences for species’ ability to persist in or invade urban environments. For example, urban environments frequently alter predator communities, exposing prey to novel predators or predator abundances. Increasing attention has focused on traits that promote urban tolerance or success (“ideal urban dweller” hypothesis). Among these traits, risk-taking behavior is thought to be especially important, as it shapes responses to altered predation risk and human cohabitation. Despite this interest, recent meta-analyses indicate that the literature is heavily biased toward avian systems, leaving other taxa, including nocturnal mammals, underrepresented. To address these gaps, we compared brown rats (Rattus norvegicus), a highly commensal, urban-dwelling species, with western deer mouse (Peromyscus sonoriensis), a native, non-urban species. Brown rats rely heavily on humans for resources such as food and shelter, traits that have likely facilitated their global urban invasion, whereas deer mice rarely occur in urban environments. We will identify rat and mouse populations on Lewis & Clark College campus and adjacent forest using camera traps, then assess each population’s response to perceived predation risk through two experiments: 1) measuring giving-up density (GUD) in exposed vs sheltered environments; and 2) a predator manipulation experiment using owl call playbacks. We will complement these data with an observational study relating owl presence (verified via camera traps and acoustic recordings) to rodent activity. Together, these data will allow us to test whether species with differing urban tolerance exhibit fundamentally different behavioral responses consistent with adaptation to urban environments.