TY - JOUR T1 - Negative effects of agricultural intensification on energetic gain rates of a declining aerial insectivore JF - bioRxiv DO - 10.1101/2021.03.24.436831 SP - 2021.03.24.436831 AU - Daniel R. Garrett AU - Fanie Pelletier AU - Dany Garant AU - Marc BĂ©lisle Y1 - 2021/01/01 UR - http://biorxiv.org/content/early/2021/03/25/2021.03.24.436831.abstract N2 - The historical rise of intensive agricultural practices is hypothesized to be related to declines of grassland and aerial insectivorous birds. Drivers of declines may also influence the overall abundance and spatial distribution of insects within agricultural landscapes. Subsequently, average energetic gain rates of birds breeding within more agro-intensive landscapes may be impacted. Lower energetic gain rates in agro-intensive landscapes may lead to reduced growth rate, body condition or fledging success of nestlings but also to diminished body condition of food provisioning adults. In this study, we assessed if energetic gain of nestlings and food provisioning behavior of adults varied across a gradient of agricultural intensification in a declining aerial insectivore, the Tree swallow (Tachycineta bicolor). We found that hourly gain rate was lower in agro-intensive landscapes, and yet travel distances were longest within less agro-intensive landscapes. Our results highlight that, in order to maximize long term average gain rates, Tree swallows breeding within agro-intensive landscapes must forage with greater intensity, perhaps at a cost to themselves, or else costs will transfer to growing broods. Our work provides further evidence that agricultural intensification on the breeding grounds can contribute to the declines of aerial insectivores in part through a trophic pathway.Competing Interest StatementThe authors have declared no competing interest. ER -