REPRODUCTIVE BIOLOGY OF THE VIOLET-CHESTED HUMMINGBIRD IN VENEZUELA AND COMPARISONS WITH OTHER TROPICAL AND TEMPERATE HUMMINGBIRDS

We provide details on the breeding biology of the Violet-chested Hummingbird (Sterno- clyta cyanopectus) based on 67 nests studied in YacambuNational Park, Venezuela, from 2002 through 2006. Clutch size was two white eggs, usually laid every other day. Fresh egg mass (0.95 6 0.14 g) was 15% of female mass. Incubation and nestling periods were 20.4 6 0.3 and 26.0 6 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 5 0.28) was slow. Daily predation rates decreased across stages and were 0.064 6 0.044, 0.033 6 0.008, and 0.020 6 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, pro- viding further evidence that this family shows a relatively narrow range of life history variation.