The influence of clutch and brood sizes on nesting success of the biscutate swift, Streptoprocne biscutata (Aves: Apodidae)

Abstract

The nesting success of three colonies of Streptoprocne biscutata (Sclater, 1866), and the influence of clutch and brood size on nesting success of species were studied. Overall, apparent nesting success was 58% and Mayfield nesting success was 53%. Nest survival during incubation (64%) was lower than during the nestling period (83%). During incubation, clutches were lost to rain, desertion, predation, egg ejection, egg damage, and egg disappearance. During the nestling period, losses occurred due to offspring disappearance, nestling death by starvation, predation and falling. During both incubation and nestling periods, predation was low, while egg ejections and nestling starvation were the main causes of nest failure. Nest survival during incubation was directly proportional to clutch size, while during the nestling period it was inversely proportional to the brood size. Apparently, there seemed to be an advantage to having more eggs during incubation. However, if all eggs were to hatch during unfavorable weather the nest success could be low. These results suggest that when the breeding pairs face adversity during incubation, they control the brood size by ejecting part of the clutch

Effect of natural brood size variability on growth and survival of thornbird nestlings

“…Research on the effect of brood size has been focused on species of the Northern Hemisphere (see reviews by Dijkstra et al, 1990;VanderWerf, 1992), whereas such studies on South American birds are scarce (but see Moreno et al, 2005;Styrsky, Brawn & Robinson, 2005;Pichorim, 2011;Sousa & Marini, 2013). South American ornithofauna comprises more than 30% of the bird biodiversity of the world (Auer et al, 2007) and in some cases, exhibits life-history traits contrasting those of northern species, including smaller brood sizes, many nesting attempts during the breeding season, long development periods and slow growth rates (Ricklefs, 1976;Yom-Tov, Christie & Iglesias, 1994;Russell et al, 2004;Auer et al, 2007).…”