What should I do with unhatched eggs or dead young in the nest?
Eggs can fail to hatch for a variety of reasons: infertility, environmental conditions like weather or chemical use, or physical damage to the eggshell. There is also an increase in the chance of infertile eggs as the breeding season progresses—it takes a lot of energy to create and lay the eggs, and sometimes this can mean smaller clutch sizes and decreased chances of hatching in later nests. Likewise, young can die in the nest for several reasons. NestWatchers often ask what should be done with unhatched eggs or dead young, especially in cases when the nest is likely to be used again (e.g., a nest box, a nest on your porch).
Once the nest is “inactive”—that is, there are no viable eggs or live young—it is safe, and legal, to clean out a nest. We recommend disposing of those eggs, deceased young, and/or nest materials (e.g., if you’re cleaning out a nest box) in a place where they won’t attract insects to the nest area. If there are dead nestlings or unhatched eggs in an “active” nest (one that also contains living eggs or young) then it’s best to leave them in the nest until the other young fledge to reduce disturbance. If you suspect a clutch will not hatch, we recommend waiting four weeks past the expected hatch date before removing the eggs. This allows for a possible delay in incubation, as well as variation in incubation period lengths. It is illegal to handle or remove a native bird’s nest while it is still active, and we have had several reports of monitors that assume their nest has been abandoned, only to find later that eggs have hatched, meaning that the adult was tending to the nest all the while. Once you’re sure eggs won’t hatch, you can remove dead eggs from the nest and remove soiled nesting material as needed.
Unfortunately, many birds’ nests are unsuccessful in the wild, and even when monitors do everything possible to help increase those chances, there are still some things beyond our control. Rest assured this is one of the reasons why birds lay so many eggs and can have multiple broods per year—they are compensating for the inevitable losses they will endure.