High Apparent Annual Survival and Stable Territory Dynamics of Chestnut-Backed Antbird (Myrmeciza exsul) in a Large Costa Rican Rain Forest Preserve

Abstract

Antbirds (Thamnophilidae) are a diverse component of neotropical forest avifaunas, and are particularly vulnerable to population declines and extirpations in fragmented landscapes. We lack estimates of apparent survival and dispersal for the majority of species, despite their value in effectively managing populations of understory birds. We studied a population of Chestnut-backed Antbird (Myrmeciza exsul) from 2004 to 2009 in a large rain forest preserve in northern Costa Rica to generate estimates of apparent annual survival (ϕ), and breeding dispersal (i.e., movement from one breeding territory to another) in continuous forest. Estimates of ϕ (± SE) of adults based on weighted model averages were high (males: 0.794 ± 0.037; females: 0.798 ± 0.050) compared to independent juveniles (males: 0.629 ± 0.159; females: 0.629 ± 0.168). Detection (recapture/reobservation) probabilities (p) were higher for males (adults: 0.916 ± 0.034; juveniles: 0.915 ± 0.049) than for females (adults: 0.544 ± 0.104; juveniles: 0.540 ± 0.115). Overall annual turnover (disappearing from the study area territory switching) was comparable to other antbirds (∼32%). Territory switching was rare, and generally limited to short movements to adjacent or nearby territories (mean distance moved = 372 m, range = 145–840 m, n = 9). Our results suggest Chestnut-backed Antbirds: (1) have relatively high adult annual survival, and (2) have limited breeding dispersal, even in a large, forested study area.