Bird Biology
Swallow
Identification:
Swallows have about 8 members of the
Hirundinidae Family living in the North American Region. Of the 8, only 2
regularly build mud nests attached to buildings, and other structures. The
Cliff Swallow (Hirundo pyrrhonota) and the Barn Swallow (Hirundo rustica)
are most often in conflict with humans the most. Cliff swallows will live
in colonies of up to several hundred pairs. Barn swallows usually nest as a
single pair or a few pairs in one structure. "The cliff swallow, 5 to 6
inches in length, is the only squared-tailed swallow in most of North
America." It has a "pale, orange-brown rump, white forehead, dark, rust
colored throat, and steel-blue crown and back. The barn swallow, 5.75 to
7.75 inches long, is the only swallow in the United States with a long,
deeply forked tail. Barn swallows have steel-blue plumage on the crown,
wings, back, and tail. The forehead, throat, breast, and abdomen are rust
colored." The females are usually duller in color than the males.
Habitat:
"Four basic conditions are found near most cliff and barn swallow nest sites: (1) an open habitat for
foraging, (2) a suitable surface for nest attachment beneath an overhang or
ledge, (3) a supply of mud of the proper consistency for nest building, and
(4) a body of fresh water for drinking."
General Biology:
Both cliff and barn swallows migrate to South America for the winter.
They will begin their return north
in late winter and early spring. Swallows travel during the day and catch
flying insects along the way. The migratory route of a swallow will always
have an abundant level of flying insects. Swallows have a tendency to
return to the same nest year after year, under suitable conditions. Most
swallow nests are inhabited by "hematophagous (bloodsucking) insects and
mites. Swallow bugs (Oeciacus vicarius), most common in cliff swallow
nests, can spread rapidly from nest to nest." "Swallow bugs reduce nestling
growth rates and cause up to half of all nestling deaths." These bugs are
able to survive in unoccupied nest for up to 3 years. When swallows are
picking out a nest, they will asses which nesting sites have a large
infestation of swallow bugs and they will avoid nesting their. "Cliff
swallow nests are gourd-shaped, enclosed structures with an entrance tunnel
that opens downward. The mud pellets used by the swallows consist of sand,
silt, and clay. The inside is lined with grass, hair, and feathers. "The
nest is cemented with mud under the eave or overhang of a building, bridge,
or other vertical surface." Barn swallow nests are cup-shaped. The mud
pellets "contain coarse organic matter such as grass stems, horse hairs,
and feathers. The nest cup is profusely lined with grasses and feathers.
Both male and female swallows help build the nest. They have to take their
time, allowing the mud to dry and harden. Depending on the climate, nest
construction could take up to 2 weeks. "A typical cliff swallow's nest
contains about 900 - 1400 mud pellets. Swallows lay their eggs during early
spring. Male and female swallows help incubate the eggs. Incubation usually
occurs before the last egg is laid. "Whitewash on the ground below the nest
or on the rim of the nest entrance is a sign of newly hatched nestlings
inside the nest. Juvenile swallows will leave the nest approximately 24
days after hatching. After leaving the nest, swallows can stay near the
nest, but normally they will start migrating south around late summer.
Damage:
"Cliff swallows nest in colonies and often live in close association with humans." Because of cliff
swallows nature to build clustered mud nests, they can do a lot of damage
to a structure aesthetically. They also cause a health hazard around humans
because of the heavy infestation of swallow bugs, mites, and ticks. Even
though barn swallows live in smaller numbers, they cause the same amount of
damage.
Legal Status:
"In the United States, all swallows are classified as migratory insectivorous birds under the
Migratory Bird Treaty Act of 1918." All states offer swallows the same
protection. One must obtain permission from local, state, and federal
officials to treat for swallows. As a general rule, if eggs or nestlings
are present in a nest, a permit authorizing nest removal must be obtained.
A permit for swallow nest removal can only be issued if very compelling
reasons exist.
Damage Prevention:
Prior to nesting season, all areas that have been used for nesting must be barricaded so that the
swallow can not rebuild its nest.
Acknowledgement:
Courtesy of The Internet Center for Wildlife Damage Management
Methods of Treatment: