PARENT SESSION
Contributed Oral Session 17: Reptiles and Amphibians: Habitat; and Communities
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal
Choosing the safest route when homing to the pond: Frog orientation in an agricultural landscape.
Mazerolle, Marc*,1, 2, 3, Vos, Claire1, 1 Alterra Wageningen University and Research Center, Wageningen, The Netherlands2 Université Laval, Québec, QC, Canada3 USGS Patuxent Wildlife Research Center, Laurel, MD, USA
ABSTRACT- Movements are important regulators of demographic processes in animal populations. However, movement patterns are potentially disturbed when individuals encounter hostile environments such as roads, logged forests, or agricultural fields. In this study, we investigated the orientation ability of pond-breeding amphibians in an agricultural landscape. We hypothesized that when presented with a choice between a short route through a hostile environment and a longer but safer route, amphibians select the one that will entail the less risk. To do so, we conducted a field experiment in the Netherlands with 108 green frogs (Rana esculenta) during the breeding season. Individuals were translocated into a recently harrowed field according to two treatments: the distance to their pond of origin (5-70 m) and the distance to a wooded hedgerow (17.5 vs 35 m). Each frog was observed during 30 min. and its initial orientation recorded. Though frog orientation was not influenced by the distance to the pond, frogs oriented towards the hedgerow when it was close (17.5 m). Their ability to orientate also decreased with wind velocity. Surprisingly, frogs did not orient systematically towards the hedgerow when it was closer than the pond. The tradeoff between a safe but longer route and hostile shortcut possibly was not sufficiently contrasted and experiments at higher scales will provide more insight on these results. Nonetheless, this highlights that successful homing behavior in amphibians in hostile environments depends on both the proximity of habitat and weather variables.
Key words: Movement, Orientation, Behavior, Landscape