Meeting Abstract

18.1  Saturday, Jan. 4 10:15  Between-individual variation in the flight altitudes of Swainson’s Thrushes BOWLIN, MS*; ENSTROM, DA; MURPHY, BJ; JURICH, P; PURDY, C; PLAZA, E; COCHRAN, WW; COCHRAN, J; University of Michigan-Dearborn; Illinois Natural History Survey; University of Michigan-Dearborn; University of Michigan-Dearborn; University of Michigan-Dearborn; University of Michigan-Dearborn; Illinois Natural History Survey; JDJC Corp mbowlin@umd.umich.edu

Radar can track individual migratory birds at night for tens of minutes and in some cases even longer, but in most cases little if anything is known about the individual being studied. Here, we present continuous flight altitude data from 12 Swainson’s Thrushes (Catharus ustulatus) making full (6-8 h) migratory flights over the midwestern United States. We used new ~1g altitude radiotransmitters and a radiotracking vehicle to collect our data. To our surprise, the thrushes did not select a consistent altitude for the majority of their flight; instead, most repeatedly gained and lost over 60% of their maximum altitude throughout the flights. We will present our data and discuss some potential explanations for this seemingly maladaptive behavior.