Northern Prairie Wildlife Research Center
Data for the present study were collected from 1988 through 1996. We began observing between 14 and 28 June (when the pups were 10-25 days old) and ended in early August. We did not attempt to randomly sample behaviors; rather, we observed as many food deliveries as we could. Although our efforts varied with logistics and weather each year, general procedures were the same except in 1988 when we observed continuously for one 5-day period.
We identified adult-sized wolves on the basis of gender (from the urination posture), behavior toward the observer, fur coloration, and such individual features as a missing tooth, ear notch, and scars (Mech 1995b). Pups were not individually recognizable, but as yearlings they demonstrated the habituation they had received as pups. Nonhabituated wolves from other packs fled when approached (Mech 1995b).
Over 9 years, six adult-sized wolves were observed with six litters (Table 1). "Mom" produced pups from 1986 through 1989, and she remained as an auxiliary when post-reproductive, behavior we have not seen documented elsewhere. Her daughter, "Whitey", replaced Mom as breeder from 1990 through 1996 (Mech 1995b; L.D. Mech, unpublished data). No other offspring remained for more than 3 summers after its birth year. Presumably they dispersed or died (Mech et al. 1998).
|Table 1. Composition of the study pack of wolves.|
|Year||No. of pups||Breeders||Auxiliaries|
|1988||4||Mom||Left Shoulder||Whitey||Grey Back|
|1994||1||Whitey||Left Shoulder||Explorer||Grey Back II|
|Note: No data were collected in 1989; no pups were produced in 1993 or 1995.|
Our observations were made at several home sites unobscured by vegetation. All behavior was recorded from the time a foraging wolf returned until it disappeared or observations were terminated. Each time a wolf regurgitated was one event, and all the regurgitation events after a return constituted a regurgitation bout. Only five observations of regurgitation bouts were incomplete (e.g., the wolves went behind a rock or ridge). In three cases when wolves regurgitated into a cache, the senior author later dug up the cache and weighed the contents.