Does dispersal help regulate the Jackson elk herd?

Elk (Cervus elaphus) that summer in Grand Teton National Park (GTNP) are pa rt of the migratory Jackson elk herd and have been hunted in portions of GT NP since 1950 to control population size. Our purpose was to determine whet her dispersal of juvenile elk from natal summer ranges (herd segments) cont ributed to limitation of population size and thereby reduces the need for h unting in GTNP. None of the 81 yearlings, 55 2-year-olds, and 25 3-year-old s captured and radiocollared as neonates during 1990-1992 dispersed out of the Jackson herd unit. However, 15% of radiocollared juvenile elk (yearling s and 2-year-olds) within the Jackson herd unit annually dispersed into or out of Grand Teton National Park during 1991-1993. Dispersal out of GTNP (1 2 of 94, 13%) to summer ranges of relatively lesser elk densities was simil ar (P=0.38) to dispersal into GTNP (8 of 43, 19%). Only 1 of 25 3-year-old radiocollared elk dispersed. Male-biased dispersal into GTNP was corroborat ed by greater yearling male:cow ratios of elk censused in GTNP than outside the park (P<0.001). Yearlings (14 of 81) and 2-year-olds (6 of 55) that di spersed to new herd segments experienced greater hunting mortality (32%, P= 0.008) than those that did not disperse (10%), and harvest mortality was ma le-biased (P=0.003). These results suggest that dispersal out of the Jackso n elk herd was not a population-regulating influence and dispersal out of G rand Teton National Park was not a limiting influence on growth of elk numb ers in the park. We conclude that at current elk densities, which are artif icially maintained by winter feeding, hunting remains a necessary control o n elk numbers in Grand Teton National Park.