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Double-brooding is an avian breeding strategy where birds produce at least two successful nests in a single season. Double-brooding is seen most frequently in small passerines for which the breeding season is lengthy enough that they can easily fit in multiple nesting attempts. Such a pattern of breeding is therefore less common among large birds with long incubation periods and slow offspring development. In the case of hornbills (Family Bucerotidae), double-brooding would be unexpected for not only these reasons, but also due to the fact that the females of nearly all hornbill species exhibit a synchronous moult of flight feathers immediately following clutch completion. Double-brooding would thus require not only an exceptionally long breeding season, but also that females undergo two very costly flight feather moults in a single season. Here we describe the double-brooding of 10 individual female Southern Yellow-billed Hornbills Tockus leucomelas in a single Namibian population during the 2019/2020 breeding season. Because the breeding cycle of Yellow-billed Hornbills lasts three months, double-brooding requires that conditions remain appropriate for breeding for more than half the year, a stringent requirement in a relatively arid country. Our analysis demonstrates that double-brooding is not a response to either small spring brood sizes or the disappearance of fledglings and appears not to be limited to females of above-average mass. Rather, we found that double-brooding is most common among females who initiated their spring nest early and appears to be associated with wetter-than-average years. [ABSTRACT FROM AUTHOR]

Understanding the breeding cycle of wildlife is essential to afford conservation strategies. This is especially important for barely studied species and urgent for those at serious risk of extinction. The Andalusian Buttonquail is an endangered endemic of the Western Mediterranean, confined to a cultivated strip in the Moroccan Atlantic coast. We performed 2 302 sampling events to determine the presence-absence and breeding of the species. The breeding season lasted for eight months, from February to October. Present in 17 different crops, breeding occurred in all but cucumber and artichoke. However, a strong preference for breeding crops was found for alfalfa, pumpkin and maize fields. Nests were 82 mm × 71.4 mm grass-lined structures built on a ground scrape. Eggs had 26.14 mm mean maximum length, 20.24 mean diameter and weighed 5.9 g. All complete clutches had four eggs and the hatching rate was 3.42. All but one of the monitored nests successfully reared at least one chick. Clutch size and hatching rate matched other Buttonquail populations and species, so causes of the decline must be found in other stages of the reproductive cycle. In this sense, additional studies are needed to reveal chick and juvenile survival. [ABSTRACT FROM AUTHOR]