Parental death destabilizes wolf packs despite the benefits of larger pack size
1. Cooperative breeding is a fundamental feature of many animal family groups. However, few studies have quantified whether variation in group size meaningfully buffers social and reproductive consequences following parental death. 2. Using 17 years of data from a gray wolf (Canis lupus) population in Oregon, USA, we evaluated how parental death (the death of one or both parents) influenced pack dissolution, reproductive failure, and pup recruitment, and whether larger pack sizes mitigated these effects. 3. Across 303 pack-years, we recorded 69 parental deaths, 39 pack dissolutions, and 112 reproductive failures. Packs that experienced parental death were nearly five times more likely to dissolve (95% CI: 2.12-11.12), nearly 16 times more likely to fail reproductively (95% CI: 5.34-47.26), and recruited 66% fewer pups (95% CI: 49-78% fewer) than packs in which both parents survived. 4. Larger packs were associated with improved demographic outcomes overall, but these group-size benefits were insufficient to fully offset the elevated risks associated with parental death. 5. Our results show that numerous individuals can provide generalized pack-level demographic resilience but do not functionally replace parental roles, highlighting the importance of evaluating social structure in addition to population size. 6. By clarifying the limits of social buffering in a cooperatively breeding carnivore, this study advances understanding of how social systems respond to parental death.