Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

Female breeding slots are the most coveted
Adaptive explanations of sex-biased dispersal include avoidance of reproductive competition - for
breeding status or resources - (Dobson 1982) or of inbreeding (Harvey and Ralls 1986). In Ethiopian
wolves observations of same-sex aggression prior to female dispersal support the competitionfor-breeding-status
hypothesis (Sillero-Zubiri 1994; Sillero-Zubiri and Macdonald 1998), while
inbreeding avoidance also plays a role (Randall et al. 2007). In Bale, only the dominant female in
each pack typically breeds (Sillero-Zubiri et al. 1996a; Marino 2003b; Randall et al. 2007), indicating
a high level of reproductive competition. Between 1988 and 1992 each breeding female was clearly
dominant over her daughters, and, in all study packs with more than one subordinate female the
lowest ranking female left the group at 18-28 months-old (Sillero-Zubiri 1994). During this period 14
subordinate females emigrated or disappeared from focal packs, whereas only four entered a different
pack and two returned to their natal group, suggesting that approximately 57% of dispersing females
either died or failed to find residence in the study population. Of the 14 females known prior to
dispersal, 10 settled as floaters next to their natal territory (Sillero-Zubiri et al. 1996a).
Figure 1. Mean pairwise relatedness (± SE) for (a) individuals with known kinship, and (b)
individuals with unknown kinship. Numbers above bars indicate (a) number of dyads or (b) number
of packs from which mean values were calculated (from Randall et al. 2007).
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 68