Frequency and correlates of birth-site fidelity in pronghorns (Antilocapra americana)

Although a variety of species exhibit birth-site fidelity, examples from ungulate species are rare. We recorded birth-site locations of pronghorns (Antilocapra americana) at the National Bison Range in northwestern Montana during 2000-2004 and found that 82% of females changed locations from the previous year. Females that exhibited birth-site fidelity had successfully weaned more fawns and were less likely to have experienced a fawn mortality event in the previous year than females that changed birth sites. Females that weaned a single fawn or weaned 0 fawns were equally likely to change birth sites. There was a year effect on distribution of birth sites as well as on birth-site fidelity. Dry range conditions in 2003 after multiple years of low precipitation may have caused more females to move their birth sites to areas of greater forage availability. The low observed frequency of birth-site fidelity may be a result of high fawn mortality rates at the National Bison Range. Success in the previous year appears to be one of the environmental cues that pronghorn females use to select a birth site.