Résumé
In birds with double-nesting and uniparental incubation, such as the rock partridge Alectoris graeca saxatilis, the male incubates one clutch, while the female incubates the other. A previous study found no significant difference in hatching and predation rates on Alpine rock partridge nests incubated by each sex. We therefore hypothesized that the incubation rhythms of both sexes would be similar. To test this, we monitored the incubation patterns of 40 nests incubated by females and 41 nests incubated by males in the French Alps between 2011 and 2020. Temperature loggers were installed within and outside the nests to record internal and ambient temperatures at 3-min intervals. Incubation recess timing and duration were inferred from the analysis of temperature curves. We employed statistical modelling to assess the effects of the incubating bird’s sex, minimum ambient temperature, incubation day, clutch size, and recess rank on various incubation parameters. The timing, total duration, and number of recesses, as well as nest temperature, were found to be similar between the sexes. On average, birds took 2.5 recesses per day, with each recess lasting approximately 75 min. Overall nest attendance was ≃ 88%. Recesses occurred throughout the day, with a peak after sunrise and a second, less pronounced peak before sunset. Nocturnal recesses were rare and resulted from disturbances to the incubating bird. Modelling results indicated only slight differences in the mean recess duration between the sexes throughout the incubation period. Further analysis showed that both sexes adjusted their incubation rhythms in a similar manner in response to the progress of incubation and to daily minimum temperatures. Cold temperatures may compel parents to spend more time foraging to meet their energy needs. Rock partridges exhibited lower nest attendance compared to grouse species inhabiting cold environments, likely due to their relatively lower body reserves.