MOVEMENTS, SURVIVAL, AND SETTLEMENT OF RED SQUIRREL (TAMIASCIURUS-HUDSONICUS) OFFSPRING

Movement and settlement patterns of animal offspring, along with the c osts of occupying familiar and unfamiliar habitats, have been inferred frequently, but rarely have they been documented directly. To obtain such information, we monitored the individual fates of 205 (94%) of th e 219 offspring born over 3 yr in a population of the North American r ed squirrel (Tamiasciurus hudsonicus), at Fort Assiniboine, Alberta, C anada (54.20 degrees N, 114.45 degrees W). We located neonates by radi o-tracking mother squirrels, and thereafter we documented the movement s, survival, and settlement patterns of the offspring, using a combina tion of telemetry, live-trapping, and visual observations. Prior to se ttlement, offspring made forays of up to 900 m ((X) over bar = 126 m) off the natal territory, but they did not abandon the natal territory until they had settled on their own territory. Foray distance was not related to the age or size of the offspring. We used the locations of offspring kills to show that the risk of predation significantly incre ased when the offspring were travelling off of their natal territories . Just under half of the 73 offspring that acquired territories did so on or immediately adjacent to their mother's; the farthest settlement distance was only 323 m from the natal territory, or about the distan ce of three territory widths. Movement data from adults in the populat ion showed that all offspring settled within potential contact of thei r mother (and possibly their father). Offspring that settled relativel y farther away from their natal territory were more likely to obtain l arger territories, with traditional hoarding and overwintering sites ( middens). These offspring also had higher overwinter survival, suggest ing that the costs of making forays off the natal territory may be bal anced by the advantages of locating a superior territory.