Predation of Rock Partridge Alectoris graeca saxatilis nests incubated by males and females in the French Alps

Abstract

ABSTRACT Capsule The predation of incubated nests was investigated in an Alpine population of Rock Partridges, showing a double-nesting behaviour by females that can lay two clutches in succession, one incubated by the mated male and the second by the female. Aims To compare the nest predation rate and hatching success between incubating males and females in relation to the potential effects of year, nest age, and environmental characteristics (presence of nest cameras, visibility of the clutch, and vegetation cover around the nest). Methods The fate of 100 nests incubated by radio-tracked birds was monitored daily over 1738 days using cameras, and with temperature loggers placed in the nest cup. Nest predation rates and daily predation rates were calculated and modelled. Results Egg predation was the main cause of nest loss (87%) followed by predation of the incubating parent during recess periods off the nest (10%). Only mammals were identified as nest predators, and predation events were less frequent during the day than at night. We found no difference in predation rates between nests incubated by males or females. Daily and 25-day predation rates were calculated as 0.02 (95% CI: 0.01–0.03) and 0.39 (95% CI: 0.29–0.49), respectively. Median hatching success was 0.91 (n = 53 nests) and did not differ between sexes. Conclusions The similar level of nest predation between incubating males and females suggested a duplication of the reproductive output of a pair by double-nesting. Consequences of this breeding system were an increase in productivity at the population level. There was no difference in hatching success in nests incubated by either sex and there were no observations of surviving males deserting their nests, suggesting that care during incubation was similar in males and females. Variation in the rate of double-nesting may contribute more than nest predation to the annual variation in reproductive output.