Homesite attendance as a measure of alloparental and parental care by gray wolves (Canis lupus) in northern Yellowstone National Park

Abstract

Cooperative breeding in mammals is quite rare. Helping with care of young by alloparents tends to be associated with monogamous family groups where dispersal of alloparents is delayed. This study focused on homesite attendance as one form of indirect alloparental care. Differences and similarities were examined between alloparental and parental care by gray wolves, Canis lupus, in a recolonizing population in northern Yellowstone. Radio telemetry supplemented by direct observations was used to observe four packs for five months and over two denning seasons. Proportion of attendance in each 24-hour sample period was plotted for each individual. A spline smoothing technique was used to analyze trends in den attendance. This innovative statistical technique was applied to matched comparisons of individuals, controlling for parental status, gender and age. A total of 29 comparisons were distributed among three categories: alloparent/alloparent (N= 8), parent/parent (N=9) and parent/alloparent (N=12). For alloparents, homesite attendance by females was greater than or equal to males in 100% of the cases. Comparing parents, females attended the den greater than or equal to males for the first 10 weeks of the pup's lives. The difference declined with age of the pups in 5 of 8 comparisons. Alloparental attendance was less than or equal to parental attendance in 7 of 12 cases. Considerable variation occurred in trends of both alloparental and parental homesite attendance. To understand the sources of this variation it will be necessary to develop approaches for meta-analysis to compare cases across groups, populations, and species. Factors to consider in a meta-analysis should include: age, multiple litters in a pack (polygamy), number of alloparents, measurement technique, and time effect (both pup development and change in food availability). Results were consistent with the variation predicted by the life history perspective on cooperative breeding. Implications for the parental manipulation and ecological constraints models of cooperative breeding are discussed.