Cuckoos are the most successful deadbeat moms in the animal kingdom. These birds might abandon their babies but not without making sure they have the very best shot at life.
Common cuckoo mothers have a significant amount of biological success at the expense of mothers from a completely different species. This phenomenon is called brood parasitism, and it’s fairly widespread in the bird world. First, an expectant cuckoo has to find the perfect parents so that she can place her babies. She embarks on scouting trips to find nests of other species that are in the right location, in the best condition, and have eggs that will hatch just a few days after as her own. Once she’s found the right nest, there’s little the host parents can do to stop the process. This is due to the myriad of evolutionary adaptations that make cuckoos successful brood parasites.
Since the orphaned cuckoo will hatch just a little earlier than the rest, it will be larger, stronger and louder than its pseudo-siblings. The most demanding bird babies are generally fed the most food, and therefore have the best chance at living. Many hatchlings have similar physical characteristics, so the host parents may not even realize a chick isn’t their own until weeks later when the cuckoo starts to stand out. In extreme cases, the adoptive parents are making the best of a dangerous situation, because alternative scenarios could be worse. For example, some parasitic cuckoo mothers will kill to ensure the survival of the eggs they abandon. After laying her own egg, she will use her strong, sharp beak to poke holes in the eggs of the host. Mother cuckoos, called ‘evicting brood parasites’, actually remove all of the host eggs from the nest before laying their own. Due to these threats, host parents may be doing the best they can under the circumstances.