Nest survival and predation in Blue-fronted Parrots Amazona aestiva: effects of nesting behaviour and cavity characteristics

ARAMBURÚ, R. M.; REBOREDA, J. C.; ARAMBURÚ, R. M.; REBOREDA, J. C.; BERKUNSKY, I.; RUGGERA, R. A.; BERKUNSKY, I.; RUGGERA, R. A.; SEGURA, L. N.; SVAGELJ, W. S.; SEGURA, L. N.; SVAGELJ, W. S.

ARDEA

NEDERLANDSE ORNITHOLOGISCHE UNIE

Año: 2016 vol. 104 p. 143 - 151

0373-2266

In this work we identify factors affecting nest survival in Blue-fronted Parrots breeding in the Chaco region of northern Argentina. We combined temporal and environmental variables in order to determine which best explain variation in (a) nest survival and (b) nest survival in relation to predation exclusively. We predicted that high and deep cavities (inaccessible for snakes and other predators) would have high daily survival rates. We compared the relative effects on nest survival of: (1) time of the breeding season, (2) stage of the nesting cycle, and (3) different characteristics of the nest cavity. We modeled daily survival rate for all observed nests (DSR), and daily survival rate for only nests that had been predated (daily survival rate in relation to predation exclusively, DSpR). Nest predation accounted for 50% of nest failures. DSR was on average 0.989, translating into an apparent hatching success of 0.39. DSR decreased with time of breeding and increased with nest age. DSpR decreased with time of breeding and inclination of the nest cavity entrance hole and increased with height from the ground of the entrance hole. There was a quadratic effect of nest age on DSpR, such that daily survival was highest during incubation, lowest at hatching and the early nestling stage but increasing throughout the remainder of the nestling stage. This effect became more pronounced as the breeding season advanced. Year and observer effects did not affect the probability of survival. Temporal patterns and characteristics of the nest cavity explained most of the variation in nest survival in Blue-fronted Parrots, which highlights the relevance of including these covariates in future studies of nest survival in parrots, and has important management and conservation implications.