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A Ten-Year History of the Demography and
Productivity of an Arctic Wolf Pack

Discussion


Whitey's productivity was low compared to that of her mother and to that of wolves in lower latitudes, which usually average litter sizes of five to six (Mech, 1970). This could be related to inbreeding depression (Laikre and Ryman, 1991) if Whitey and Left Shoulder are siblings. However, at the high latitude where this pack resided, average litter sizes appear to be about two to three (Marquard-Petersen, 1994), so Whitey's production may not be unusual.

The cause of Whitey's lack of reproduction in 1993 may be related to the fact that all three of her 1992 pups survived into 1993. Feeding three pups from birth through the breeding season may have left Whitey with too few body reserves to ovulate, conceive, or carry pups to term. During summer 1993, both Whitey and Left Shoulder regularly delivered food to their three yearlings, and the yearlings often remained at rendezvous sites like most pups do through their first 5 months. Such an explanation would not account for Whitey's barrenness in 1995, however, for 1994's pup was not present then. Also notable is the fact that neither Whitey's 1990 pup nor her two 1991 pups survived beyond autumn, and probably her 1994 pups failed to survive.

The data obtained in this study are consistent with what is known about wolf pack demography from other areas (Fritts and Mech, 1981; Mech and Hertel, 1983; Peterson et al., 1984; Fuller, 1989; Gese and Mech, 1991; Meier et al., in press), except for Whitey's low productivity. However, this study extends that information in several ways, demonstrating the breeding tenures, productivity, and intrapack relations of individual wolves, documenting the high survival of young pups through the summer, and questioning the cause of one female's relatively low productivity and survival of pups.


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