Factors affecting the success of artificial pack formation in an endangered, social carnivore: the African wild dog

Abstract

Social integration is an important factor when reintroducing group-living species, but examples of the formation of social groups before reintroduction are largely lacking. African wild dogs Lycaon pictus are endangered, and reintroductions have become a routine part of range expansion in South Africa. Wild dogs form packs that are essential to their reproduction and survival, and artificial pack formation is often required before reintroduction. We examined the proximate (i.e. social integration) and ultimate (i.e. reproduction) success of 43 artificial pack formation attempts in the South African managed metapopulation, between 1995 and 2018. The top (and dominant) model for proximate success included an interaction between total group size and an initial separation fence. Larger groups took longer to integrate, irrespective of initial separation, whereas smaller groups brought together immediately integrated faster than those that were initially separated. The top models for ultimate success included an interaction between the proportion of males and number of days spent in the pre-release enclosure, the total number of days in the enclosure and an interaction between the proportion of captive-sourced individuals and the total number of days in the enclosure. Ultimate success increased when packs spent less time in the enclosure, especially if those packs had a low proportion of males (i.e. female biased) or included >25% captive-sourced individuals. Neither the size of the artificially created pack nor the season in which the pack was released affected ultimate success. The success of social integration and reproductive success of artificially formed packs in this study was higher than for natural pack formations. We provide guidelines for optimizing future artificial pack formation in wild dogs for reintroduction success. Our results serve as an example of the practical importance of social behavior in successfully implementing conservation measures for group-living species.

The successful reintroduction of African wild dogs (Lycaon pictus) to Gorongosa National Park, Mozambique

“…No wild dogs escaped from the enclosure during this period. From the behavioral monitoring sessions at the enclosure, we estimated pack cohesion and acclimatization in order to identify suitable timing of release and were guided by reintroduction time frames that optimize short-term and long-term success [ 47 ]. In the week prior to release, we administered booster vaccinations for CDV via drop-out darts.…”

“…For wild dogs, new pack formation is key to demography and population growth [ 42 ]; Packs can form both naturally [ 43 , 44 ] or artificially such as with opposite-sexed and unrelated cohorts being bonded together in pre-release enclosures [ 45 , 46 ]. Pre-release artificial bonding is a crucial indicator that enhances group cohesion [ 15 , 47 ], promotes alpha pair establishment [ 48 ], positively influences post-release reproduction [ 47 ], and is effective in the reintroduction phase for a new population [ 16 , 37 ]. Post-release survival of founders is also a key indicator [ 18 , 37 , 49 , 50 ], as is consecutive years of breeding of the release generation coupled with natural recruitment [ 37 , 39 ] ( Table 1 ).…”

Changes in social groups across reintroductions and effects on post‐release survival

“…Groups integrated in captivity pre-release can be more cohesive and survive better post-release, compared to immediately released groups (Gusset, Slotow & Somers, 2006;Hunter et al, 2007). However, improved group cohesion is not guaranteed (Clarke et al, 2003) and there are other implications of delayed release as it can reduce post-release survival (Castro et al, 1994;Richardson et al, 2013), lower breeding success (Marneweck et al, 2019) or increase stress (Batson et al, 2017). Thus, the benefits of temporary captivity are likely species-specific (Moseby, Hill & Lavery, 2014) and understanding a variety of its advantages and disadvantages (including social cohesion) is important when evaluating its use (IUCN/SSC, 2013).…”

Untitled

“…Thus, future reintroduction efforts (into fenced or unfenced areas) should place high priority on bonding of artificial packs and acclimating already formed packs in prerelease enclosures (i.e. a soft release approach) as these pre-release procedures have important impacts on fitness [47]. Intensive daily monitoring at the pre-release enclosure allowed us to assess individual dynamics to confirm pack cohesiveness, alpha pair establishment and habituation to their new environment.…”

“…For wild dogs, new pack formation is key to demography and population growth [42]; Packs can form both naturally [43,44] or artificially such as with opposite-sexed and unrelated cohorts being bonded together in pre-release enclosures [45,46]. Pre-release artificial bonding is a crucial indicator that enhances group cohesion [15,47], promotes alpha pair establishment [48], positively influences post-release reproduction [47], and is effective in the reintroduction phase for a new population [16,37]. Post-release survival of founders is also a key indicator [18,37,49,50], as is consecutive years of breeding of the release generation coupled with natural recruitment [37,39] (Table 1).…”