I haven’t seen an adult bird in a while. Is the nest abandoned?
You may see birds very frequently as they build their nests—they are constantly flying back and forth as they add more and more materials to their nest. However, once the nest is built, the adults often seem to disappear. This is because the female is now visiting the nest only once each day to lay an egg, and often in the early morning. Once the entire clutch is laid, one or both parents will begin incubating and will minimize activity around the nest to avoid detection by predators. Soon the eggs will hatch, and you’ll start seeing the adults moving around again; they’ll be flying back and forth constantly, only this time with food in their beaks.
For a nest containing eggs, it’s best to allow four weeks to account for a possible delay in incubation as well as the typical incubation time (this may need to be extended by a week or two for species with longer incubation times, such as ducks). If you do not see any adults near the nest and there is no progress (no hatched eggs, etc.) after four (or more) weeks, the nest may have been abandoned.
For a nest containing young, often nestlings may appear to be abandoned when they are actually not. When young are old enough, they don’t have to rely on their parents for warmth and the adults also don’t need to visit as often, and may only be stopping by very quickly to deliver food. The less activity there is at the nest (i.e. the parent visiting it and moving around nearby) the less likely it is to attract predators. We have several reports from participants who believe a nest is abandoned, only to find that the eggs hatch or young fledge in the normal span of time, which indicates that the parent(s) were tending the nest all the while.
Typically, birds may abandon nests for a variety of reasons: they may have been disturbed too often, often by predators or human activity; something may have caused the eggs to be nonviable (infertility, environmental conditions, or a cracked eggshell); or the parents themselves could have run into trouble. Sometimes, if one parent dies, the other may abandon the nest, especially in species where they rely on each other to successfully feed and raise the chicks. Nests with young are rarely abandoned, and therefore, you should not intervene unless you are certain that both parents have been killed (or the main caregiver, for species in which only one parent cares for the young). Do not try to care for the egg/young yourself. In this case, the next step is to call a federally certified Wildlife Rehabilitator, or a wildlife veterinarian.
If you believe your nest is abandoned, wait about four weeks from the last time you saw an adult at the nest. This accounts for the typical incubation period for songbirds (two weeks) and an additional two weeks to account for a possible delay in incubation. If the nest is unchanged after this period, then it was likely abandoned.