Mortality, home range, and habitat use of pronghorn fawns within tallgrass prairie of eastern Kansas.

Abstract

During 1991 and 1992, 12 and 34 pronghorn fawns (Antilocapra americana), respectively, were captured in tallgrass prairie of east central Kansas and monitored through August of each year. Ten fawns captured during 1991 and 31 fawns captured during 1992 were fitted with ear tag radio transmitters. Summer natural mortality rates were calculated from all fawns captured, bedding site vegetation characteristics were quantified, and home ranges were calculated from fawns fitted with radio transmitters. A natural mortality rate of 58% and 90% was found in 1991 and 1992, respectively. six fawn carcasses were found, 1 in 1991 and 5 in 1992, with enough evidence to determine that coyotes (Canis latrans) were the cause of death. Hair, bone, and/or the transmitter were recovered from 19 dead fawns, 4 during 1991 and 15 during 1992. These fawns were partially consumed by coyotes. Moisture and cool temperatures did not appear to contribute to fawn mortality. Fawn home range size increased significantly (E < 0.001) with age during both years. Home ranges were larger (E = 0.0046) at 24 days of age and smaller (E = 0.0038) at 60 days of age in 1992. Mean cover values for grasses and forbs and mean vegetation heights for 49 and 94 actual and random fawn bedding peripheral sites were analyzed during 1991 and 1992, respectively. The cover of forbs for actual surviving fawn peripheral sites was greater (E = 0.0039) than those of non-surviving fawns in 1991. The height of vegetation at surviving fawn peripheral sites was greater (E = 0.0127) than those of non-surviving during 1991. The vegetation height in actual peripheral sites for non-surviving fawns was greater (E = 0.0012) than random peripheral sites for non-surviving fawns in 1992. During 1991 (E = 0.0097) and 1992 (E < 0.0001) vegetation within 0.5 m of actual bedding sites of all fawns was significantly taller than vegetation within 0.5 m of random bedding sites. Bedding sites were more prevalent on slopes during 1991 (X2 = 37.01, E < 0.001) and 1992 (X2 = 215.47, E< 0.001). Bedding site cover appears to be adequate for pronghorn fawns in tallgrass prairie. I suggest the increased mortality of 1992 compared to 1991 was a result of a different vegetation distribution and increased movements by fawns during 1992.