Wiktionary
a. (context biology of a bird English) That leaves the nest shortly after hatching
WordNet
adj. (of birds) leaving the nest shortly after hatching [ant: nidicolous]
Wikipedia
Nidifugous organisms are those that leave the nest shortly after hatching or birth. The term is derived from Latin nidus for "nest" and fugere meaning "to flee". The terminology is most often used to describe birds and was introduced by Lorenz Oken in 1816. The chicks of birds in many families such as the waders, waterfowl and gamebirds are usually nidifugous.
The term nidifugous is sometimes used synonymously with precocial, as all nidifugous species are precocial – that is, born with open eyes and capable of independent locomotion. However, not all precocial birds leave the nest; some may stay at the nest, and are thus considered to be nidicolous.