title: Let's stay together? Intrinsic and extrinsic factors involved in pair bond dissolution in a recolonizing wolf population.
abstract: For socially monogamous species, breeder bond dissolution has important consequences for population dynamics, but the extent to which extrinsic or intrinsic population factors causes pair dissolution remain poorly understood, especially among carnivores. Using an extensive life-history data set, a survival analysis and competing risks framework, we examined the fate of 153 different wolf (Canis lupus) pairs in the recolonizing Scandinavian wolf population, during 14 winters of snow tracking and DNA monitoring. Wolf pair dissolution was generally linked to a mortality event and was strongly affected by extrinsic (i.e. anthropogenic) causes. No divorce was observed, and among the pair dissolution where causes have been identified, death of one or both wolves was always involved. Median time from pair formation to pair dissolution was three consecutive winters (i.e. approximately 2 years). Pair dissolution was mostly human-related, primarily caused by legal control actions (36·7%), verified poaching (9·2%) and traffic-related causes (2·1%). Intrinsic factors, such as disease and age, accounted for only 7·7% of pair dissolutions. The remaining 44·3% of dissolution events were from unknown causes, but we argue that a large portion could be explained by an additional source of human-caused mortality, cryptic poaching. Extrinsic population factors, such as variables describing the geographical location of the pair, had a stronger effect on risk of pair dissolution compared to anthropogenic landscape characteristics. Population intrinsic factors, such as the inbreeding coefficient of the male pair member, had a negative effect on pair bond duration. The mechanism behind this result remains unknown, but might be explained by lower survival of inbred males or more complex inbreeding effects mediated by behaviour. Our study provides quantitative estimates of breeder bond duration in a social carnivore and highlights the effect of extrinsic (i.e. anthropogenic) and intrinsic factors (i.e. inbreeding) involved in wolf pair bond duration. Unlike the effects of intrinsic and extrinsic factors that are commonly reported on individual survival or population growth, here we provide quantitative estimates of their potential effect on the social unit of the population, the wolf pair.
authors: Faculty of Applied Ecology and Agricultural Sciences, Hedmark University of Applied Sciences, Evenstad, N-2480, Koppang, Norway.
authors: Cyril
authors: C
authors: Milleret
authors: Faculty of Applied Ecology and Agricultural Sciences, Hedmark University of Applied Sciences, Evenstad, N-2480, Koppang, Norway.
authors: Petter
authors: P
authors: Wabakken
authors: Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, SE-730 91, Riddarhyttan, Sweden.
authors: Olof
authors: O
authors: Liberg
authors: Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, SE-730 91, Riddarhyttan, Sweden.
authors: Mikael
authors: M
authors: Åkesson
authors: Norwegian Institute for Nature Research, Tungasletta 2, 7485, Trondheim, Norway.
authors: Øystein
authors: Ø
authors: Flagstad
authors: Faculty of Applied Ecology and Agricultural Sciences, Hedmark University of Applied Sciences, Evenstad, N-2480, Koppang, Norway.
authors: Harry Peter
authors: HP
authors: Andreassen
authors: Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, SE-730 91, Riddarhyttan, Sweden.
authors: Håkan
authors: H
authors: Sand
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D005260:Female; D008136:Longevity; D008297:Male; D009664:Norway; D010152:Pair Bond; D011157:Population Dynamics; D011158:Population Growth; D012621:Seasons; D013548:Sweden; D019596:Wolves / Q000502:physiology*
keywords: 
  Canis lupus
  ; anthropogenic; extrinsic; inbreeding; intrinsic; pair bond duration