POPULATION-DYNAMICS OF A RECOLONIZING WOLF POPULATION

Breeding populations of wolves (Canis lupus) were absent from the west ern United States for about 50 years following their extirpation by hu mans in the 1930s. Here we describe the recolonization by wolves of no rthwestern Montana and southeastern British Columbia, from the initial production of a litter by a pair of wolves in 1982 through the mid-19 90s when 3-4 packs produced litters. Sex ratio of captured wolves favo red females (38/54 = 70%; chi(2) = 8.96, 1 df, P < 0.005). Litter size in early summer ((x) over bar = 5.3, SE = 0.4, n = 26) and in Decembe r ((x) over bar = 4.5, SE = 0.5, n = 26) were relatively high compared to similar counts in established populations elsewhere. Pack size in May was unrelated to litter size in lune (r(s) = -0.13, 23 df, P = 0.2 5) or the following December (r(s) = -0.12, 23 df, P = 0.28). Annual a dult survival rate (0.80) was relatively high in this semi-protected p opulation and was higher among residents (0.84) than among wolves that dispersed (0.66) from the study area (Z = 2.24, P = 0.025). Although dispersal was common among radiocollared wolves (19/43 = 44%), populat ion growth within the study area averaged 20% per year from 1982 to 19 95. Low human-caused mortality rates and maintenance of connectivity f or wolves between this small population in the United States and large r populations in Canada will enhance the probability of persistence an d expansion of this population.