Maternal care and thermal stability during nesting in Phaethornis longirostris (Long-tailed Hermit)

Abstract

In birds, as in other endothermic vertebrates with parental care, during nesting, parents must invest large amounts of time and energy to maintain thermal stability of eggs and chicks. Nest homeothermy is selectively advantageous for parents as it increase hatching success, offspring survival, and offspring development rate. Hummingbirds, characterized by their high metabolic rates and exclusively maternal care, the females must optimize time and energy devoted to different behaviors related to parental care during nesting and in particular to maintain nest homeothermy. In this study we evaluated in a nest of a Long-tailed Hermit hummingbird (Phaethornis longirostris), the effect of maternal care on quality and stability of the thermal environment of its progeny. We used an ultra thin thermocouple connected to an electronic thermometer to record thermal variation ambient inside the nest. Our results showed that although the female leaves the nest for long periods to feed, their nest and progeny maintains a great thermal stability (variation less than 1ºC). This suggests that the female attending her nest optimized its maternal care patterns (i.e. incubation and foraging), in order to minimize thermal oscillation experienced by its progeny. Although we still need to assess the contribution of other maternal care decision such as building materials and nest shape as well as the election of nesting site in thermal stability of the nest.