Songbirds are members of the order Passeriformes. This group of birds, commonly known as passerines, comprises a range of bird families; it is our most varied group of birds both in terms of numbers of species and diversity of appearance and habit preferences. Songbird members range in size from the tiny Golden-crowned Kinglet (our smallest bird) to the massive Common Raven.
Songbirds have feet that allow them to perch with ease. Three toes point forward and one faces back; this provides support and allows the bird in question to stand upright on level ground, and enables it to grasp comparatively slender twigs and branches with a sure grip.
As their name suggests, songbirds are—to a greater or lesser degree—extremely vocal, and males of some species are among the finest songsters in the bird world. Many territorial males advertise ownership of breeding grounds and attract and retain mates by loud and diagnostic songs. And all species have a repertoire of calls that serve a variety of behavioral functions, including alarm (for example, at the presence of a predator) or contact (with other members of the species in feeding flocks or on migration).
Songbird diet is as varied as the appearance of the birds themselves, but for many species small invertebrates are important for at least part of the year—typically the spring and summer months, when nesting is taking place. Some songbird families, such as warblers, feed almost exclusively on invertebrates, while sparrows and buntings rely to a great degree on seeds as a source of nutrition, particularly during the winter months. Many crow family members are arch scavengers that, to a certain extent, have predatory habits too. But in shrikes, the predilection for live prey reaches its apogee, the birds behaving like miniature raptors and even having hook-tipped bills to aid dismembering victims.
Most songbirds lead rather solitary lives during the breeding season and nest in relative isolation from pairs of the same species. However, outside the breeding season some form sizable flocks that migrate, feed, and roost together. There is some truth in the saying that there is safety in numbers, because there are plenty of eyes on the lookout for danger.
In some songbird species, visual differences between the sexes are subtle (to our eyes at least). Behavioral differences obviously play an important role in gender recognition for the birds themselves, but in the case of certain species it is only when a male is heard singing or when nesting behavior is observed that we as observers can be certain of the sex of a bird. However, among many songbird groups there are striking differences in plumage, although often these differences are more apparent in breeding plumage than during the winter months.