by
Alex Kim
Department of Biology
Davidson College, Davidson, NC

Part I: Hypothesis Development

Grey wolves (Canis lupus) are territorial pack animals. The pack usually consists of a male, a female, and their offspring. Most breeding pairs (the alphas male and the alpha female) are monogamous. Pups are normally born late spring and early summer. The weaning process begins when the pups are about three weeks old and ends when they are about four to five weeks old. Afterwards, they feed on regurgitated food. Their eyes remain closed until they are about two weeks old. After about 20 days, their milk teeth come in. Young from the previous breeding season will help support their parents in nursing pups. Wolf cubs are submissive to their parents even after reaching sexual maturity. Wolves will usually remain with their parents until they’re about 2 years old.In terms of both quantity and nutrient quality, maternal milk has been known to vary over time in relation to offspring growth and demands.

J.M. Packard et al. studied the weaning behavior of grey wolves. Theoretically, pups would have evolved to ask for more milk than their lactating mother was able to give. However, a parent-offspring conflict might result in a mechanism within the mother to control milk transfer. Environmental factors can change the magnitude of the conflict during weaning.

Ballenberghe et al. studied the growth of gray wolves in Minnesota. Weights, growth rates, canine tooth lengths, and survival data were obtained from 73 wolf pups that were between 8 to 28 weeks old.

Questions:

Generate some hypotheses to explain how gray wolves “know” when it is time to start weaning. Use the questions below to help you generate your hypothesis

1) When would begging behavior in the offspring be most intense?

2) When would the parent most likely try to resist giving up milk?

3) When would parent-offspring conflict be greatest between the pups and their mother during the weaning period?

4) Who would benefit before, during, and after the weaning period?

5) How would resource availability and maternal condition affect the length of weaning?

6) How would the pup’s growth effect the weaning process?

Part II: Hypotheses and Predictions

This website was completed by Alex Kim in partial fulfillment of the requirements for Biology 323, Animal Behavior, at Davidson College in the Spring Semester 2009.
Any questions or comments regarding this website should be directed towards Alex Kim or Dr. Verna Case
Animal Behavior Homepage

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