According
to authorities Charles R. and Mary B. Brown, The Birds of North
America, the Cliff Swallow is one of the most social - and more
quarrelsome - of all our landbirds. During the breeding season,
it lives in colonies that may have hundreds to thousands of pouch-shaped
mud nests attached to stony surfaces. Before the 20th century, the
bird spent its breeding season primarily in the rocky foothills
of the mountains of the West, typically nesting beneath the ledges
of cliffs and canyon walls. During our expansive 20th century, it
extended its breeding season range dramatically, both northward
and eastward, capitalizing on nesting sites offered by newly constructed
bridges and buildings.
Distinctive
Features
- The
size of the bird averages 5" in length
- Relatively
chunky neck and squared tail
- Rufous-colored
cheeks and neck with a white- or buff-colored forehead and black
head cap
- Blue-black
upper parts with narrow white stripes on back between wings; orange-
to buff-colored rump
- White
to grayish under parts
- No
significant visual differences between the Male/Female
- Range
and Migration Habits
by
Jim Huddle
©James P. Huddle
The
Cliff Swallows modern, expanded summer breeding range extends
from western Alaska to southern Mexico, and spans southern Canada
and the continental United States from coast to coast (except for
our southeastern states). The Southwest populations non-breeding,
winter ranges, although imprecisely known, appear to extend through
Central America and deep into South America. Its fall and spring
migrations each last for several months.
Habitat
and Diet
Typically, according to the Browns, the Cliff Swallows preferred
breeding season habitats lie near bottomlands, open forests, cultivated
fields or grasslands - locations with concentrations of flying and
swarming insects, the birds favorite prey. It favors locations
near streams, lakes or ponds, particularly if there is a source
of mud for use in nest building. It normally avoids open desert
basins and dense forests that lie beyond reasonable access to water
and mud. It may set up housekeeping at elevations ranging from near
sea level to some 9000 feet.
The
Cliff Swallow's preferred nesting sites - in the foothills of the
mountain ranges of the West - includes cliff faces and canyon walls
in drainages, hills, escarpments and rock outcroppings. Its preferred
sites - in its more recently adopted, expanded habitats - include
vertical concrete surfaces beneath horizontal structural ledges
of highway bridges and culverts and buildings.
The
birds winter habitat, even though not definitively mapped,
appears to include marshes, fields and grasslands. During the non-breeding
season, it may be nomadic, moving and searching continually for
insect concentrations. Its migratory routes take it across a wide
diversity of landscapes, sometimes moving with flocks of thousands.
Behavior/Life
Cycle
Prior
to and during nesting, the Cliff Swallow typically forages as part
of a flock, which facilitates discovery of insect prey concentrations.
Those ...nesting in larger colonies feed more efficiently
and deliver more food to the offspring... say the Browns.
The bird also drinks as part of a group while skimming the waters
surface.
With
the approach of mating, the cantankerous Cliff Swallow may fight
for a nest site, especially in the more central and protected parts
of a colony. It may peck and flog a competitor. It may also attack
or defend a completed nest, doing battle at the entrance or within
the nest itself. For good measure, it may chase a competitor in
flight or knock it from a perch. It may raid an unattended nest,
attacking, and sometimes even killing, nestlings.
A
Cliff Swallow pair builds a nest with approximately 1000 mud daubs
and lines it with grass, often sharing walls with adjacent nests.
The pair may also refurbish and reuse a nest from a previous year.
When breeding, the male and female mate at a nest, often before
it is complete, sometimes falling from the nest during the act of
copulation. They form a relationship marked by marginal mutual tolerance,
short duration and the males philandering.
A
few days after mating begins, the female starts laying cream-colored
eggs in the nest. Given a chance, she may lay an egg in another
females nest, or she may transport one of her eggs to another
nest. She may even summarily discard an another birds egg
from another nest. Of course, she may suffer reciprocation by other
females. In the end, the male and female usually raise a clutch
of perhaps two to six eggs of mixed parentage.
The
male and female incubate the eggs for about two weeks, when hatching
begins. The parents dispose of the egg shells, dropping them from
the nest entrance. For the next three weeks, both forage for insects,
compressing them into paste-like balls and feeding them to the naked,
reddish-colored and clamoring young. Over the following week, through
fledging, the parents continue to care for the young, feeding them
in flight, guiding them home at dusk. The two dissolve the family
bond after the fledglings reach independence and join juvenile flocks.
With
the end of summer, the Cliff Swallow begins to feel the call of
its winter home.
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