American Robin Egg

It's never a good sign to see a mostly-intact American Robin egg on the ground. While finding half an eggshell leaves open the possibility of a successful hatching and the shell falling from a nest, it's clear that no baby robin came out of this cracked but largely intact shell.

Exactly what happened is unclear. Perhaps a predatory bird broke into the egg, ate the contents, then discarded the shell. Although I don't think American Robins are the most common targets of brood parasitism, I can't rule out that a Brown-headed Cowbird chick hatched 1st and tossed out the other eggs to get all the food/nutrition the parents could provide. Conventional parasites and diseases no doubt take a toll. And although robin nests tend to be fairly sturdy cups, it's not impossible that bad weather knocked the egg out of the nest.

This is a reminder that many eggs don't hatch and many nestlings don't survive to adulthood. Though many birds have the potential for explosive population growth, predators and limited resources usually put the breaks on that growth. Most bird species are lucky if they're able to maintain a population level despite all the threats and challenges they encounter.

May 14, 2023 at Duke Farms
Photo 292808164, (c) jpviolette, some rights reserved (CC BY-NC)


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