Bizarre!
Perhaps, I overlooked it, but what the article did not mention is whether these birds eat meat at all as regular food. According to Wikipedia: "The diet of the Eurasian hoopoe is mostly composed of insects, although small reptiles, frogs and plant matter such as seeds and berries are sometimes taken as well."
"When food is bountiful, the Eurasian hoopoe ... will lay a few “extra” eggs for a gruesome reason: so a parent can feed the youngest hatchlings to its older chicks.
Among scientists, the idea that some animals store abundant food by producing extra offspring is known as the larder hypothesis. Previous studies have shown that animals including ladybird beetles and sand tiger sharks practice such lardering behavior. But the study of hoopoes in Spain, published last month in The American Naturalist, offers the first evidence of lardering in a vertebrate that invests a substantial amount of energy in caring for its young, researchers say. ..."
From the abstract:
"The adaptive value of routinely laying more eggs than can be successfully fledged has intrigued evolutionary biologists for decades. Extra eggs could, for instance, be adaptive as insurance against hatching failures. Moreover, because recent literature demonstrates that sibling cannibalism is frequent in the Eurasian hoopoe (Upupa epops), producing extra offspring that may be cannibalized by older siblings might also be adaptive in birds. Here, directed to explore this possibility in hoopoes, we performed a food supplementation experiment during the laying period and a clutch size manipulation during the hatching stage. We found that females with the food supplement laid on average one more egg than control females and that the addition of a close-to-hatch egg at the end of the hatching period increased the intensity of sibling cannibalism and enhanced fledging success in hoopoe nests. Because none of the extra nestlings from the experimental extra eggs survived until fledging, these results strongly suggest that hoopoes obtain fitness advantages by using temporarily abundant resources to produce additional nestlings that will be cannibalized. These results therefore suppose the first experimental demonstration of the nutritive adaptive function of laying extra eggs in vertebrates with parental care."
Extra Nestlings That Are Condemned to Die Increase Reproductive Success in Hoopoes (no public access)
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