Characteristics of dispersal in a colonizing wolf population in the central Rocky Mountains

Gray wolves (Canis lupus) were eradicated from Montana in the 1930s and the adjacent Canadian Rockies by the 1950s, but recolonized these areas in the 1980s. We studied wolf recovery in and neat Glacier National Park (GNP), M ontana, from 1979 to 1997. During this period, 31 of 58 tagged wolves dispe rsed. Most wolves (57%) did not make exploratory forays 3 months before per manent separation from their natal pack. Wolves usually left their natal ho me range quickly: (median = 4 days; mode = 1 day) after separating from the pack. Mean dispersal distance was not different (P > 0.05) between males ( 113 km) and females (78 lan), excluding an unusually long dispersal of 840 km by a yearling female. Wolves tended to disperse in a northerly direction to areas of higher wolf density. January-February and May-June were peak m onths for dispersal. Mean dispersal age (M = 28.7 months; F = 38.4 months) was not correlated with maximum pack size. Twenty percent of dispersers wer e greater than or equal to 57 months old at dispersal. Sex ratios of disper sers and captured wolves (both 71% F) differed from parity (P = 0.002). Ann ual survival rate ((x) over bar +/- SE) for dispersers and biders (philopat ric wolves) did not differ (dispersers = 0.76 +/- 0.10; biders = 0.77 +/- 0 .14). Wolves killed by humans died closer to roads ((x) over bar = 0.13 km) than wolves that died from other causes ((x) over bar = 0.85 km). Eighty p ercent (n = 30) of wolf mortalities were caused by humans, with proportiona tely mere dispersers (90%) than biders (60%) dying from human causes. Dispe rsers produced more litters than biders. Effects of mountainous terrain and management on wolf recovery are discussed.