Environmental drivers of incubation routine in a sex-role reversed shorebird

Abstract

Incubation is a critical phase of reproduction, during which parents must balance the thermal requirements of embryos with time spent away from the nest for self-maintenance. In species with uniparental care, this trade-off may be especially constrained by environmental conditions. Understanding how environmental factors shape incubation behaviour is therefore vital for understanding avian reproductive ecology and incubation routine. Here, we investigate the influence of environmental factors on the incubation behaviour of male African Jacanas Actophilornis africanus, a sex-role-reversed species at Lake Hawassa, Ethiopia. Using 24-hour video recordings from 20 nests, we quantified hourly incubation constancy and recess frequency across the diel cycle. Males exhibited a strong diel rhythm (F = 33.12, p < 0.001; n = 480 hours of recordings from 20 nests), with a higher incubation constancy at night (51.4 min h^-1; 86%) than during the day (31.1 min h^-1; 52%). Daytime incubation was variable. Generalised additive mixed models (GAMMs) revealed that ambient temperature and wind speed predicted incubation constancy, whereas ambient temperature, wind speed and egg-laying date predicted recess frequency. At lower ambient temperature and higher wind speed, incubation constancy increased, whereas recess frequency decreased. This study provides evidence that local environmental conditions shape incubation routines in a sex-role reversed shorebird, highlighting the plasticity of parental care strategies under different environmental regimes.