Characteristics of Nocturnal Birds
Nocturnal birds are quite different than their diurnal (daytime) cousins. Physically, these birds have a number of traits different from more familiar daytime birds. For example:
Dull Plumage Colors: Because bright colors are difficult to see at night, most nocturnal bird species lack red, blue, orange or other bold colors. Instead, these birds have more muted plumage with shades of brown, gray, black and white. Males and females typically look very similar. Heavily Camouflaged Patterns: Heavily mottled, camouflaged patterns are common among nocturnal birds. When these birds are roosting during the day, strongly camouflaged plumage helps them blend into their surroundings and keep them safe from predators. Larger Eyes: Nocturnal birds often have eyes that are exceptionally large in relation to their head and body size. These oversized eyes help collect what limited light is available to enhance their vision. Enhanced Senses: In addition to larger eyes for better vision, other senses, such as hearing and smell, may be more acute in nocturnal birds than in diurnal birds. For example, owls have facial disks that help enhance their hearing.
Birds that are active at night also behave differently than daytime birds. When they are spotted during the day, they may seem relatively tame and calm, but that is a defense mechanism rather than a sign of mellow behavior. These birds will instinctively freeze and remain immobile when they feel threatened in the daylight, hoping that their camouflage conceals them and trying not to attract additional attention by moving. To safeguard these species and let them get a good day’s rest, birders should never approach nocturnal birds too closely in the daytime. As a good rule of thumb, if the bird has opened its eyes and is watching you, you’ve already alerted it and disturbed its rest, so it is best to back away and leave it in peace.
Nocturnal Bird Species
It can be difficult to classify a bird species as strictly nocturnal, since many species will be active whenever they need to be, including at odd times if food supplies are scarce or if they are under stress. When most of a bird’s normal activity occurs during the darkest nighttime hours, however, that species is generally considered nocturnal. The most familiar, generally nocturnal birds include:
Ashy storm-petrelsFrogmouthsKakaposKiwisLittle penguinsNight-heronsNight parrotsNightjarsOwlet-nightjarsOwlsPauraquesPoorwillsPotoosStone-curlewsWoodcocks
In addition to these species and groups of birds that are typically regarded as nocturnal, many other bird species are crepuscular, meaning they are most active at twilight or just before dawn. Birds are considered to be nocturnal, though, only if they are readily active in the darkest parts of the night. Many species may be considered both nocturnal and crepuscular.
What Birds Do at Night
Nighttime birds follow the same activity patterns as daytime birds, just during different hours. At night, nocturnal birds will forage for food or hunt for prey, preen, build nests, exhibit courtship behaviors, and do whatever other tasks are necessary for their survival. During the day they roost and sleep, just as diurnal birds do during the night. There are occasions, particularly in spring and fall, when more birds than usual may be active at night. In the spring, the dawn chorus may break out several hours before daybreak as diurnal birds seek to claim territories and attract mates with their melodious tunes. Some diurnal birds may even sing at night when there is enough light to trigger their vocalizing instincts, such as during a full moon or near a bright streetlight. In the fall, many otherwise daytime birds may migrate at night, thus avoiding the attention of migrating hawks and other aerial predators and taking advantage of star patterns for clearer navigation. Despite these limited seasonal activities, however, birds that are only occasionally active at night are not considered nocturnal.
Birding at Night
Finding nighttime birds can be a challenge, but it is one well worth taking. Birders should always keep birds’ best interests in mind, however, whether they are taking a specific owling hike or just visiting a local patch after dark to see what birds might be active. Learning how to identify birds at night takes patience and practice, but understanding what birds are likely to be nocturnal is the first step to enjoying birds all through the night.
