Meeting Abstract

P3.3  Saturday, Jan. 5  An estimation of female home-range size during the nestling period in Dark-eyed Juncos (Junco hyemalis) REICHARD, D.G.*; KETTERSON, E.D.; Indiana Univ.; Indiana Univ. dgreicha@indiana.edu

The transition from eggs to nestlings marks a period of increased effort for female songbirds as individuals begin to forage for nestlings in addition to themselves and continue to devote a large amount of time to brooding. This increase in energetic expenditure during the early nestling period predicts an increase in female activity, but a decrease in female home-range size in comparison to the rest of the nesting cycle as females attempt to forage near the nest to minimize their energy loss. Using radio telemetry and GIS software, we estimated the home range size of seven female Dark-eyed Juncos (Junco hyemalis) three days after their nestlings had hatched. We attached radio transmitters using a leg-loop harness and tracked these females for two hours on the afternoon of day three of nestling life and two hours in both the morning and afternoon on days four and five. Female location and behavior was noted every ten minutes for the duration of the tracking. Home-range size was found to vary greatly between individuals, which may be attributable to differences in resource availability and the relative densities of conspecifics. As expected, female behavior was dominated by brooding and foraging, and in most cases females varied their foraging sites. Conspecific interactions outside the pair-bond were noted only three times throughout the duration of the study and all were agonistic. We will compare female home-range size during the nestling period to both male and female juncos at other periods in the nesting cycle and to other species based on data in the literature. Studies of home-ranges such as this provide unmatched insight into a species� resource management, time budget, and social interactions under free-living conditions.