Natural History and Breeding Biology of the Rusty-breasted Antpitta (grallaricula Ferrugineipectus)

—We provide substantial new information on the breeding biology of the Rusty-breasted Antpitta (Grallaricula ferrugineipectus ferrugineipectus) from 40 nests during four consecutive breeding seasons at Yacambú National Park in Venezuela. Vocalizations are quite variable in G. ferrugineipectus. Nesting activity peaked in April when laying began for half of all nests monitored. The date of nest initiation pattern suggests this species is single-brooded. Both parents incubate and the percent of time they incubate is high (87–99%) throughout the incubation period. The incubation period averaged ( SE) 17.0 0.12 days, while the nestling period averaged 13.37 0.37 days. G. f. ferrugineipectus has the shortest developmental time described for its genus. Time spent brooding nestlings decreased as nestlings grew, but was still greater at pin feather break day than observed in north temperate species. The growth rate constant based on mass (k 0.41) and tarsus length (k 0.24) was lower than the k for north temperate species of similar adult mass. All nesting mortality was caused by predation and overall daily survival rate ( SE) was relatively low (0.94 0.01) yielding an estimated 15% nest success. Received 13 January 2007. Accepted 25 July 2007. Breeding biology and life history traits of most neotropical birds are poorly known and antpittas are no exception (Krabbe and Schulenberg 2003, Rice 2005). The small antpitta genus Grallaricula comprises eight species (Krabbe and Schulenberg 2003). Nest descriptions and scanty breeding information are available for G. ferrugineipectus, G. nana, G. flavirostris, and G. peruviana (Krabbe and Schulenberg 2003). The most detailed study to date is that by Schwartz (1957) for the Rusty-breasted Antpitta (G. f. ferrugineipectus) where the description of nest and breeding biology was based on only three nests in a forest (850–900 m elevation) south of Petare, Edo. Miranda, Venezuela. Information on the exact length of incubation and nestling stages, parental behavior, predation rates, and nestling growth rates remain unknown. Our objective 1 USGS, Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT 59812, USA. 2 CICyTTP-CONICET, Materi y España, Diamante (3105), Entre Rı́os, Argentina. 3 Grupo FALCO, Calle 117 Nro 1725 e/66 y 67, La Plata (1900), Argentina. 4 Departamento de Biologı́a de Organismos, Universidad Simón Bolı́var, Apdo. 89000, Caracas 1080-A, Venezuela. 5 Corresponding author; e-mail: [email protected] is to provide data on these previously undocumented life history traits and other natural history information for G. f. ferrugineipectus based on detailed field observations. Field work was conducted during four consecutive breeding seasons from 2003 to 2006 at Yacambú National Park, Edo. Lara, a montane cloud forest area in north-central Venezuela (09 42 N, 69 42 W; 500–2,200 m elevation). Means are presented with one standard error (SE) unless otherwise noted.