Antipredator Behaviour in Nesting Zenaida Doves (Zenaida Aurita): Parental Investment or Offspring Vulnerability

1. Zenaida doves (Zenaida aurita) nested on several small islands near Culebra, Puerto Rico, under rocks, herbs and low shrubs. When humans approached their nest sites, doves either walked surreptitiously, flew, or burst explosively from the nest when the intruder was very near. 2. Incubating parents usually walked from the nest, parents with hatching eggs usually walked, but sometimes flew from the nest, and parents with chicks usually flew from the nest. 3. Only parents with hatching eggs or chicks gave distraction displays. 4. Variations in flushing distance depended on stage in the reproductive cycle and study island, whereas distance initially flown from the nest also depended on distance to colony edge, and time to remain near the nest also depended on nesting stage and island. 5. Level of nest defense and parental risk increased at hatching, but did not continue to increase with age of the chick. Our data support SKUTCH (1949) and ANDERSSON et al.'s (1980) vulnerability hypothesis for parental care rather than TRIVER'S (1972) cumulative investment hypothesis.