Statistical modeling of social biology in giant Canada geese in the Upper Cumberland region of Tennessee

Populations of giant Canada geese (Branta canadensis maxima) have been established throughout Tennessee and other states in eastern North America. Geese are highly social birds that congregate in complex social units. The primary goal of this study was to analyze the giant Canada goose population in the Upper Cumberland region of Tennessee using banding and observation data gathered from 1998-2011. Specifically, objectives were to: (1) determine abundance trends, (2) model population parameters, (3) estimate breeding probability by sex and age, (4) compare statistical models of factors affecting membership in social units, (5) compare best-fit models resulting from classical and Bayesian methods, (6) delineate social units within the Upper Cumberland population, and (7) quantify the persistence of and interchange among these social units.;During the 14-year study, 4,691 different geese were banded in the study area. Abundance in 2011 was an estimated 2,036, an increase of approximately 2.3% per year since 2001. Average annual survival was 80.7%, while fidelity and immigration were 82.5% and 51.6%, respectively. The Upper Cumberland flock consists of three subflocks (eastern, western, and southern). Only about one-third of adult geese were reproductive, with females reaching peak breeding probability at age seven and males at age nine. Stronger bonds and higher pair membership were indicated for the western and southern subflocks than in the eastern subflock. Females were approximately 35% more likely to continue associating with members of the same brood aggregation than males.;Pairs, families, multi-generational relatives, and former brood aggregate members had higher association indices and greater association strengths (≥0.58 and ≥19.27, respectively) than did non-breeding season units and subflocks (≤0.16 and ≤5.85). Standardized lagged association rates were higher for members of pair, families, brood aggregations, and for multi-generational relatives than for random groupings of individuals, suggesting stable, long-term associations. Breeding UC geese may receive benefits of territory establishment and defense before the breeding season, along with greater vigilance during non-breeding seasons, by maintaining associations with young-of-previous-years. These associations, along with the prevalence of non-reproductive adults, indicate a possible tendency of adult geese to remain in the UC region and forego reproduction, at least temporarily.