Distribution, migration chronology, and survival rates of Eastern Population sandhill cranes

Abstract

The Eastern Population (EP) of greater sandhill cranes (Grus canadensis tabida; hereafter, cranes) is rapidly expanding in size and geographic range. The core of their breeding range is in Wisconsin, Michigan, and southern Ontario, Canada. Little information exists regarding the geographic extent of breeding, migration, and wintering ranges of EP cranes, or migration chronology and use of staging areas. In addition, there are no published estimates of survival rates for EP sandhill cranes. To address these information needs we trapped and deployed solar Global Positioning System (GPS) Platform Transmitting Terminals (PTTs) on 29 sandhill cranes from December 2009 through September 2011, primarily in known fall and winter concentration areas, to assess movements throughout the year. This thesis explores EP sandhill crane distribution during the breeding season and winter, migratory routes, and migration chronology (Chapter 1) and also estimates survival rates during the study period (Chapter 2). EP cranes settled on summer areas beginning mid-March in Minnesota (11%), Wisconsin (36%), Michigan (29%), and Ontario (21%). On average, PTT-tagged cranes arrived at their winter terminus beginning mid-December in Indiana (29%), Kentucky (11%), Tennessee (79%), Georgia (11%), and Florida (32%). Twenty-three marked cranes returned to their summer area's calculated mean center after a second spring migration. The average linear distance between individual estimated mean activity centers for a summer area was 1.34 km (range: 0.01 - 7.82 km). EP cranes used fall and spring migration routes similar to those previously documented. Annual survival rates (from October through September) were estimated at 0.921 (2010-2011; SE = 0.058) and 0.913 (2011-2012; SE = 0.087) using the known fates platform in Program MARK (Chapter 2).