Disruptive influences of drought on the activity of a freshwater turtle

Drought is an ecological challenge for turtle species worldwide and can be exacerbated by habitat fragmentation and loss, especially for small populations. We studied the activity of 16 Blanding's turtles Emydoidea blandingii using radio-telemetry from 2005-2006 during consecutive drought and normal hydrological years at a fragmented preserve in northeastern Illinois, U.S.A. The preserve experienced drought conditions during 2005 with precipitation levels 20% below the 60 y average. Fine scale measures of activity (i.e., mean water depth at locations, proportion of unique locations, and proportion of locations in dry habitat) differed between years, whereas broad scale measures of activity (i.e., home range, movement distance) did not. On average only 41.3% of 2005 home ranges overlapped with 2006 home ranges suggesting space use shifted between years. Although most proportional habitat use remained unchanged between years, several individuals increased their use of riverine habitats when other wetland habitat dried. Our study underscores the need to examine the risks of severe environmental events on vulnerable populations.