Sex-biased survival of nestlings under unfavourable conditions drives secondary sex ratio in little owls (Athene noctua)

hat late-hatched nestlings of low body mass showed reduced survival under adverse habitat conditions, resulting in a male-biased nestling mortality. Our conclusions therefore support theoretical predictions according to which the more sensitive sex will be disproportionally affected by unfavourable conditions that were previously identified by feeding experiments in the study system. This pattern of condition-dependent secondary brood sex ratio...