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# Cannibal Chicks: The Hoopoe Hatches a Spare
- URL: https://www.gottabekidding.me/cannibal-chicks-the-hoopoe-hatches-a-spare/
- Published: 2026-10-06T10:02:24.000Z
- Updated: 2026-10-06T10:02:23.000Z
- Description: Researchers slipped one extra late-hatching egg into hoopoe nests. That chick never fledged, and the nest raised nearly two more birds anyway.
- Author: Field Notes
- Tags: Nature

A Eurasian hoopoe nest is, by most appearances, an ordinary place where small, helpless birds wait to be fed. What a 2021 breeding season in southern Spain revealed is something considerably less ordinary. In some of those nests, the youngest chick ends up as a meal in reserve.

Researchers already knew that hoopoe females (*Upupa epops*) regularly use their last-hatched nestlings to nourish older siblings. The biology makes it possible. Hoopoes begin incubating after the first or second egg is laid, so by the time the final chick hatches, its eldest sibling may be an order of magnitude heavier. A nest that looks like a family is also a size hierarchy.

What the 2024 paper tested was more specific. Could producing that surplus chick actually improve the survival of the rest of the brood?

The researchers ran two experiments. In the first, they supplied extra food to 27 nests during egg laying. Those females produced about one additional egg on average, suggesting that a temporary abundance of resources can translate directly into a larger clutch. In the second, they transferred close-to-hatching eggs between matched nests, giving 11 nests one extra chick that would hatch last. Nests that got the extra egg saw more of their chicks cannibalized. None of those added chicks survived to fledging. But the nests that received them fledged nearly two more chicks, on average, than nests from which a late egg was removed.

This is what biologists call the icebox hypothesis. When food is plentiful at laying time, a female can turn that surplus into an extra egg, and the chick it produces can later feed older siblings if food runs short. That extra egg might also start out as insurance against early losses, and the researchers note that an extra chick could also push parents to work harder. They didn't pin a single job on any one egg.

An offspring that never leaves the nest can still shape what the nest produces.

Read the full story at [The American Naturalist, February 6, 2024](https://www.journals.uchicago.edu/doi/10.1086/728883?ref=gottabekidding.me)

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**Hot Take:** Most packed lunches come with a sandwich and an apple. In a lean hoopoe year, they come with a younger sibling.