Chestnut-backed Antbird Poliocrania exsul

  • Order: Passeriformes
  • Family: Thamnophilidae
  • Polytypic: 5 subspecies
  • Authors: Stefan Woltmann, Ryan S. Terrill, Matthew J. Miller and Matthew L. Brady


Effects of human activity on populations

The widespread loss of lowland forests throughout the species’ range undoubtedly has caused large reductions in overall abundance (Ridgely and Gwynne 1989), but where forest patches remain the species typically is found in them (e.g., Wetmore 1972, Matlock et al. 2001, Roberts 2007). Chestnut-backed Antbird is abundant on Barro Colorado Island (BCI), Panama (Robinson 2001), and has persisted for some time in the Rio Palenque preserve in Ecuador (Leck 1979, Ridgely and Greenfield 2001b); both sites have been surrounded by inhospitable habitat for many years, and it has been demonstrated that Chestnut-backed Antbirds are physically incapable of flying between BCI and the mainland (Moore et al. 2008). In Gatun Lake, Panama, found on 4 of 6 islands studied in late 1970s and early 1980s (not including BCI; Wright 1985). Was present, with possible signs of inbreeding, on 3 smaller islands (Los Gatos) around BCI in late 1980s (Sieving 1991), but now extirpated from 2 of these (W. D. Robinson, pers. com.).

At La Selva Biological Reserve, Costa Rica, moderate population declines reported from 1960 – 1999 (Sigel et al. 2006). No clear population trend discernable from La Selva Christmas Bird Count data (1988-2002, Figure 13), but given variation in day-to-day vocal activity annual 1-day surveys are likely not reliable for estimating population size (SW pers. obs.).
Figure 13. Daily totals (birds per party-hour) of Chestnut-backed Antbirds recorded during the La Selva Biological Station Christmas Bird Count, 1988 – 2002.

Despite high nest predation rates (see Populations and Demography), population densities in anthropogenically isolated populations sometimes higher than in large forested areas (Robinson et al. 2000, Robinson 2001, SW unpub. data). Nest predation rates may be elevated in fragmented landscapes (e.g., Young et al. 2008), and the species’ ability to persist when many other antbirds do not could be related to high re-nesting tendency following failure (as in some other antbirds; Willis 1974, Sieving 1992, Roper 2005). However, re-nesting tendency has not been quantified in Chestnut-backed Antbird.

Recommended Citation

Woltmann, S., R. S. Terrill, M. J. Miller and M. L. Brady. 2010. Chestnut-backed Antbird (Poliocrania exsul), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.