Pack size and wolf pup survival: their relationship under varying ecological conditions

Shift in red fox, Vulpes vulpes, mating system associated with El Niño in the Bering Sea

“…Where prey were scarce among wolves, litter size and pack size were inversely correlated. Where prey were abundant, wolf pack size and litter size were positively related (Harrington et al 1983).…”

“…The size of social groups in many carnivore species has been shown to increase seasonally with food abundance, e.g. coyotes, Canis latrans (Camenzind 1978;Bowen 1981;Bekoff & Wells 1982); wolves, C. lupus (Harrington et al 1983); golden jackals, C. aureus (Macdonald 1979); brown hyenas, Hyaena brunnea (Owens & Owens 1978); and stripped hyenas, H. hyaena (Kruuk 1976;Macdonald 1978). These data support the predictions of the resource dispersion hypothesis (Macdonald 1983;Carr & Macdonald 1986) that a pair of carnivores may tolerate additional group members when there is abundant food resources, but may defend their territory against other group members when food resources are scarce.…”

Reproduction and Mortality of the High Arctic Wolf, <em>Canis lupus arctos</em>, in Northeast Greenland, 1978-1998

“…Age structure may influence productivity, because most wild female Wolves do not breed until two or three years of age, and many probably not until four or five years of age (Mech 1991). Pack size determines number of females and helpers in a pack and has been correlated with productivity (Harrington et al 1983).…”

“…Surviving litter size has been correlated with pack size (Harrington et al 1983), although some researchers found no evidence of this relationship (Pletscher et al 1997). Larger packs kill more ungulate prey than smaller packs but have less food available per pack member than smaller packs (Fritts and Mech 1981;Messier and Crête 1985;Ballard et al 1987;Messier 1987;Thurber and Peterson 1993;Dale et al 1995).…”

“…Pack members ("auxiliaries") help feed the pups in larger packs thereby increasing pup survival (Brainerd et al 2008). Pack size and litter size in an increasing Wolf population with abundant prey in Minnesota were positively correlated, and litter size in a declining population at low prey density was inversely related to pack size (Harrington et al 1983). Availability of food influenced ability or willingness of subordinate Wolves to provide food for pups, thus affecting pup survival (Harrington et al 1983).…”