Selective Pressures Influence a Grow Fast, Fly Young Strategy for Black Skimmer Populations in the Peruvian Amazon

Black Skimmers (Rynchops niger) typically nest in coastal environments. However, there are populations in South America that nest along freshwater river tributaries, where they are subjected to threats from predation and flooding that differ from coastal counterparts. We monitored Black Skimmers from a population in Manu National Park, Peru, over two breeding seasons and compared their life history traits with those of Black Skimmer populations across the Americas. Mean clutch size, daily nest survival rate, hatching success, and incubation period were within reported ranges. However, incubation bouts were short (7.33 ± 1.84 h^-1), provisioning rates were high (3.58 ± 1.35 prey items chick^-1 h^-1), and chicks fledged about 10 days earlier than typically reported in North American populations. Flooding accounted for 41%-61% of nest failures, concentrating mortality risk during early development. Across populations, initial reproductive investment appears conserved, whereas traits influencing the duration of offspring vulnerability varied. High food availability coupled with a tenuous nesting situation appears to select for individuals that exploit abundant food resources and maximize chick growth rates, such that a shortened growth period may limit exposure to stage-specific mortality influences.