![]() ![]() Some authors propose that nestlings compete with each other by trying to monopolize access to adults’ beaks. Romero)Įvidence towards this hypothesis is sparse, and where present, is controversial. The smaller chick (middle) is at an obvious disadvantage with regard to accessing adults’ beaks directly. White Stork adult at nest in Andalusia, with a larger nestling reaching out to access the adult’s beak. This absence of nestling-based aggression that results in reduction of brood sizes – as is common in herons – it is thought, forces adults to carry out the thinning of the nest. The lack of aggression, it is thought, is helped by adult behaviours of provisioning food: White Stork adults dump food into the middle of the nest giving all nestlings similar access. This in turn prevents reduction of the brood, which is a useful strategy to raise few healthy chicks especially in years and areas where food is not plentiful. Why should this be so? One common theory is that stork nestlings lack aggression, and do not prevent each other from feeding when adults return with food. ![]() White Stork adults are also infamous for filial infanticide – the killing of chicks by adults at the nest. At first sight, it is astonishing that no one is falling out of the nests, and all of the noise suggests intense fighting. The singular, remarkable aspect of storks for most people are the noisy colonies where many hundreds, even thousands, of birds assemble to nest atop tree canopies. A White Stork colony atop an oak amid pasture in Andalusia. The bigger and more active nestlings usually garner most of the food. In birds like storks where chicks are altricial, or featherless and blind at hatching, competition for food among nestlings is a common feature. In most species, jostling by senior nestlings to reduce food access of younger nestlings is common. In birds, behaviours of nestlings and provisioning adult birds are greatly varied. ![]()
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