Reproductive Biology of the Violet-Chested Hummingbird in Venezuela and Comparisons with Other Tropical and Temperate Hummingbirds

Abstract. We provide details on the breeding biology of the Violet-chested Hummingbird (Sternoclyta cyanopectus) based on 67 nests studied in Yacambú National Park, Venezuela, from 2002 through 2006. Clutch size was two white eggs, usually laid every other day. Fresh egg mass (0.95 ± 0.14 g) was 15% of female mass. Incubation and nestling periods were 20.4 ± 0.3 and 26.0 ± 0.4 days, respectively. Nest attentiveness increased from 60% in early incubation to 68% in late incubation. The female spent 50% of her time brooding young nestlings, but ceased brooding by 13 days of age. Only the female fed the young, with a low rate of nest visitation (3.3 trips per hour) that did not increase with age of the young. Growth rate based on nestling mass (K = 0.28) was slow. Daily predation rates decreased across stages and were 0.064 ± 0.044, 0.033 ± 0.008, and 0.020 ± 0.006 during the egg-laying, incubation, and nestling periods, respectively. Most, but not all, life history traits of the Violet-chested Hummingbird were similar to those reported for other tropical and temperate hummingbirds, providing further evidence that this family shows a relatively narrow range of life history variation.