From Wildlife Extra:
Female cowbirds found to be better mothers than previously thought
Researchers observed the results when female cowbirds laid their eggs in the nests of prothonotary warblers
The reputation that brown-headed cowbirds are neglectful parents, leaving their eggs in other bird nests and the subsequent care and feeding of their offspring to an unwitting foster family, could be ill-deserved a new study has found.
For rather than forgetting all about their offspring the researchers have found that cowbird mums actually pay close attention to how well their offspring do, and return to lay their eggs in the most successful host nests, and avoid those that have failed.
“No one’s ever suggested before that cowbirds or even other brood parasites pay attention to their own reproductive success.”
Cowbirds are native to North America and are one of only a few bird species that engage in brood parasitism, the practice of tricking other species into raising one’s young, the researchers said. Other brood parasites include the cuckoo, which targets nests with eggs that look very similar to its own. Some host species recognize foreign species’ eggs and roll them out of the nest.
The team found that the nests that successfully hosted cowbirds were much more likely to be parasitised again, while those that failed to fledge cowbirds were significantly less likely to be targeted by cowbird females the next time around.
While they are unable to say whether the same females are targeting the same nests again and again, the researchers said it is likely that that is the case.
“Our results mean that somebody’s paying attention, and it makes the most sense that the female that’s laying the eggs would be paying attention to her own reproductive success,” Louder said. “We think that other females are also paying attention.”