Passerines
are the perching birds -- technically members of the order
Passeriformes. Birds in this order are characterized by
having four toes, three directed forward and one backward,
all joining the foot at the same level. Orders are primary
taxonomic subdivisions of classes. Birds compose the class
Aves (we are in the class Mammalia; bees are in the class
Insecta). Roughly 60 percent of all
bird species are passerines, but only about 40 percent of
the families. Thus, this order makes up an extremely large
fraction of bird diversity, and the families within it have
a disproportionately high average number of species. Both
facts indicate the great success of the passerine way of
life: not only have a great many passerine species evolved,
but the existence of so many similar species within families
suggests a relatively low rate of extinctions, a high rate
of speciation, or both. Because the diversity of
passerine species is so extensive, and perhaps because they
are the most familiar of birds, the class Aves is often
conveniently divided simply into passerines and
nonpasserines. Within the Passeriformes, two suborders which
differ in the structure of the vocal apparatus are usually
recognized: the Oscines and the Suboscines. Only one of
eighteen passerine families represented in North America are
Suboscines: the Tyrannidae (tyrant flycatchers --
flycatchers, kingbirds, phoebes, etc.). The Oscines, divided into
about 70 families, are the "songbirds." This is the group of
birds in which singing is most highly developed. The calls
of some birds in other groups are quite musical, but it is
in the Oscines that we perceive songs to reach their full
beauty and complexity. SEE: Feet;
Bird
Voices;
Vocal
Functions;
Birds,
DNA, and Evolutionary
Convergence;
Taxonomy
and Nomenclature. Copyright
® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl
Wheye.