Reproductive Physiology of Ethiopian wolves

The Ethiopian wolf (Canis simensis) is a medium sized territorial canid, and it is endemic to the highlands of Ethiopia. With fewer than 500 individuals remaining, the Ethiopian wolf is the world’s rarest canid. Ethiopian wolves live in territorial packs of up to 13 adult animals. Although Ethiopian wolves live in packs, they usually forage solitarily and specialize in hunting rodents, especially giant molerats (Tachyoryctes macrocephalus), which is the wolves’ main food item. Breeding is monopolized by the dominant male and female, although dominant females may have extra pair copulations with males from other packs. There is a single breeding season per year, coinciding with the end of the rainy season. This study aimed to assess the reproductive physiology of Ethiopian wolves, including characterizing hormone levels throughout the breeding season and analyzing differences in hormone levels between dominant and subordinate wolves.

In order to study wolves’ reproductive physiology, faecal samples are collected from focal wolves, especially adult females. Faecal samples provide a great non-invasive way of studying reproductive physiology, as these can be collected without handling or disturbing animals. Focal animals are followed on foot and faecal samples are collected within minutes of defecation. Samples are preserved through desiccation at the campsite and later sent to the UK for analysis. Samples are then analyzed for hormones including estrogens, progestins and corticoids using radio immunoassays and enzyme immunoassays. In addition to sample collection, behavioural observations are recorded to gain detailed knowledge of wolves’ reproductive behaviours.

This study takes place in the Web Valley of Bale Mountains National Park (BMNP), in Southern Ethiopia, which is home to about half of all remaining Ethiopian wolves. A total of six focal packs were selected for this study, totalling 51 wolves. These included 13 focal females, of which six were dominant and seven were subordinate. Unfortunately, a rabies epidemic broke out in August 2008, killing about 75% of all wolves in Web Valley. This left us with only four females in three focal packs. Three of these females bred successfully despite the epidemic, the fourth female is a subordinate, non-breeding female. Nine focal females died at various stages of the breeding season, including two who died during pregnancy.

During the epidemic, several wolves in Web were vaccinated against rabies and ear tagged. We included newly vaccinated wolves in our study to assess the stress response of wolves to being trapped and vaccinated. These samples have been shipped to the UK and will be analyzed for corticoids.

This latest epidemic highlights once again the vulnerability of Ethiopian wolf populations. We hope that a greater understanding of Ethiopian wolf reproductive physiology will contribute to a better understanding of population dynamics and of the long-term conservation requirements of this endangered canid, as well as providing a better understanding of reproduction in the context of eventual metapopulation management.

This work is funded by the Institute for Breeding Rare and Endangered African Mammals (IBREAM)