Causes of Reproductive Failure in Two Family Groups of Wolves ( Canis lupus)

• Published in: Zeitschrift für Tierpsychologie
• Main Authors: Packard, Jane M., Seal, Ulysses S., Mech, L. David, Plotka, Edward D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1985
• Subjects: Tive; Canis lupus
• Online Access: http://dx.doi.org/10.1111/j.1439-0310.1985.tb00112.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1439-0310.1985.tb00112.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1439-0310.1985.tb00112.x

Abstract and Summary To examine the selective pressures influencing evolution of the nuclear family social system in canids, it is important to determine the behavioral and physiological reasons why some adults do not reproduce within a pack. Two captive wolf packs were studied during two breeding seasons. Physiological suppression of gonadal cycles was not a cause of reproductive failure of adults: ovulation occurred in five adult females that did not reproduce, and seasonal cycles of testicular development and testosterone secretion occurred in four non‐reproduc‐tive males. Reproduction in females was blocked (10 out of 12 cases) at the following stages of the oestrus cycle: pro‐oestrus (2 juveniles), ovulation (1 yearling), copulation (2 adults), met‐oestrus (1 adult and 2 yearlings), and postparturition (1 juvenile and 1 yearling). Males (7 out of 11 cases) failed to reproduce for the following reasons: immaturity (1 juvenile), no copulation (4 adults), infertility (1 adult), and possibly female immaturity (1 yearling). Thus individuals appear physiologically capable of reproduction although they may not reproduce in a social environment with high sexual competition. Following a change in social structure within each pack (deaths of the father in one pack and the mother in the other pack), offspring copulated with parents and with siblings. Thus, reproductive suppression in wolves is not caused by suppression of gonadal cycles. Offspring retain the readiness to breed given the opportunity. A complex set of factors inhibit behaviour of offspring in the presence of reproductive parents. Results of this study tentatively suggest that antagonistic relationships may have influenced the hormonal basis for sexual attractivity of females, for copulatory behaviour of males, and for age of first ovulation. Zusammenfassung Warum pflanzen sich viele adulte Wölfe im Rudel nicht fort? In zwei Rudeln brach das Fortpfianzungsverhalten von Weibchen in 10 bis 12 Fällen an folgenden Stellen ab: im Pro–Östrus (2 Junge, 10 ...