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Between-year survival and rank transitions in male Black-capped Chikadees (Poecile Atricapillus): a multistate modeling approach

Schubert, K. A., Mennill, D. J., Ramsay, S. M., Otter, K. A., Ratcliffe, L. M., Kraus, C.

The Auk, 125:3, 629-636 (2008)

Abstract

In dominance-structured animal societies, variation in individual fitness is often related to social status. Like many passerine birds, Black-capped Chickadees (Poecile atricapillus) have a short average adult life-expectancy (~2 years); however, the maximum recorded lifespan is over five times as long. Enhanced annual survival could contribute to greater lifetime reproductive success for male chickadees attaining high social rank. We used multistate capture-mark-recapture models to estimate annual survival of male Black-capped Chickadees in Ontario, Canada using resighting and recapture data collected from 1997-2002. Our goal was to evaluate support for an influence of rank on annual survival and estimate its effect size for a food-supplemented study site. We also statistically modeled the probability of between-year rank transitions. Model selection based on AIC did provide support for an effect of rank on survival. However, multimodel inference revealed the size of the effect to be rather small. Over the six study years, model-averaged estimates of the survival benefit of high versus low rank ranged from 5.0 to 7.3%. As expected, survival was strongly year-dependent, with model-averaged estimates of annual survival probability varying between 0.36 and 0.73. Age was an important predictor of the probability of rank transitions. Low-ranked second-year birds were less likely than older low ranked birds to advance to high rank between years; likewise, high-ranked after-second-year birds were less likely to drop in rank. Other studies have found larger effects of rank on survival than we observed here. Future research should consider how interactions between social and environmental factors influence annual survival.

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