Geographic Range
Although Connecticut warblers (
Oporornis agilis
) are rare and difficult to study, their general geographic range includes Southern
Canada, the north-central United States south to central South America, and parts
of the eastern United States. Their summer range has been difficult to record, whereas
the winter range for these warblers includes Venezuela, Brazil, and other regions
in northern South America. This species travels different routes during their two
yearly migration periods, which is relatively rare among migratory birds. Their spring
migration takes them through Florida to the Mississippi Valley, while their fall migration
pattern includes flying eastward to New England and south to the West Indies and South
America.
- Biogeographic Regions
- nearctic
- neotropical
Habitat
Connecticut warblers inhabit grassy areas in spruce or deciduous forests as well as
low, damp woods or swampy wilderness. Fields that are brushy, weedy, or fallow are
also favored. Habitat choice can differ across the breeding range. Additionally,
spruce
-
tamarack
forests that are poorly drained as well as drier
oak
-
pine
forests and
Jack pine
forests are common areas occupied by this species. Breeding grounds are usually dry,
open
poplar
woods,
black spruce
tamaracks, or muskeg bogs such as those of the north-central United States and southern
Canada.
- Habitat Regions
- terrestrial
- Terrestrial Biomes
- forest
Physical Description
Generally, these warblers can be identified from their grey or brownish hood, which
extends to the throat, along with olive upperparts and yellow or yellowish-white underparts.
White eye-rings are present in all plumages. Males and females are similar in overall
appearance but do have slight seasonal variations. In the spring, adult males tend
to have olive-green and brownish upperparts and blackish wings and tails that lack
any white markings. The crown plumage is slate gray and there is a complete white
eye-ring. The sides of the head, throat, and upper breast are also slate gray, but
paler on the throat. The rest of the underparts are yellow and olive-green. In the
fall, adult males are similar to adults in the spring; however, the crown is browner.
Juvenile males are similar to adult males except the crown is olive-brown with a yellowish-brown
color on the throat, relative to the gray in adults. Eye-rings are also buffy. Other
juvenile characteristics include having a paler bill and legs relative to adults.
In the spring, adult females have a similar appearance to adult males except the crown
is brownish and olive-green. The cheeks, throat, and upper-breast are brownish. In
the fall, adult females are similar in appearance to adult males in the spring, except
the upperparts and breast are browner. Juvenile females are reportedly indistinguishable
from adult males in the fall. Connecticut warblers weigh an average of 15 g and are
13 to 15 cm long. The average wingspan is 23 cm. This species is often confused with
mourning
and
Macgillivray's
warblers as they are morphologically and ecologically similar. Mourning warblers
lack eye-rings and feature black patches on the breast and Macgillivray's warblers
have broken eye-rings and a dark colored chest. These species can be distinguishing
by the larger size, complete white eye-ring, and lack of black color on the breast
of Connecticut warblers.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male more colorful
Reproduction
The mating system of Connecticut warblers has not been identified; however, birds
in order
Passeriformes
are generally polygynous or promiscuous.
The breeding range of Connecticut warblers includes eastern British Columbia and central
Alberta in the north, east to northeastern Ontario, and south to northern Michigan.
Breeding takes place in the summer season, usually from mid-June to early August.
Clutch sizes vary from 3 to 5 eggs, with an average of 4 eggs. These warblers create
nests on the ground that are deep, compact, rounded cups made of fine dry grasses,
leaves, and moss-like fibers lining the bottom. Females incubate eggs in only a single
incubation patch. The duration of incubation has not been recorded.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- oviparous
In terms of parental investment, brooding is done by the female. Parental care involves
both parents and once the eggs hatch; they help feed their young at their nest, usually
until they fledge. The fledglings are helpless the first week after hatching and are
dependent on their parents. Families remain together for about two weeks after fledging,
when the young become slightly more independent.
- Parental Investment
- female parental care
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
Lifespan/Longevity
The lifespan of Connecticut warblers has not been established. However, in New Jersey,
a banded individual had an estimated age of about 4 years. Similar species, such as
mourning warblers
and
Kentucky warblers
have an estimated lifespan of 7 and 6 years, respectively. While another related
species,
MacGillivray's warblers
have an estimated lifespan of about 4 years. Aside from predation, these birds may
experience mortality due to in-air collisions with human-made objects.
Behavior
Connecticut warblers have been described as a shy, elusive species. These birds are
often found walking quietly in their environment and have also been noted hiding within
their surroundings. Movements consist of their tail moving up and down as though it
is bouncing. The flight patterns of these warblers are similar to those of other warblers
in their genus (
Oporornis
). Although this species is often territorial and solitary, they may form flocks of
up to 25 individuals when migrating. Likewise, these birds are known to feed alongside
other bird species when they are in their breeding areas. Territoriality exists among
male adults. They are the most territorial during the summer and especially during
breeding season. This species is solitary in the wintertime.
- Key Behaviors
- flies
- motile
- migratory
- solitary
- territorial
Home Range
The exact home range size for this species has not been established. These birds maintain
territories during the breeding season, although the territory sizes can vary based
on their specific habitat. In Minnesota, breeding territories as small as 0.24 ha
were noted in open habitats, whereas territories as large as 0.48 ha were seen in
more closed habitats. The population density of this species also varies depending
on their geographic location.
Communication and Perception
Connecticut warblers primarily communicate through calls and songs. These birds make
sharp, high-pitched calls while they fly. Alarm calls sound metallic such as "plink"
or soft like "ploit" and are produced when predators are near their nests or fledglings.
Male and female adults may share call notes. Their songs can be repetitive two-part
or three-part phrases. They are loud and can be heard from far distances. Their song
pattern is similar to that of
common yellowthroats
and their pitch and rhythm are similar to that of
Kentucky warblers
. Songs are normally heard on breeding grounds, especially during the spring migration
period. This species is much quieter during the fall.
- Communication Channels
- acoustic
Food Habits
Connecticut warblers feed on
insects
such as
beetles
, as well as
spiders
,
snails
, berries, and even small seeds. In general, warblers also feed on
butterfly
larvae and caterpillars.
- Animal Foods
- insects
- terrestrial non-insect arthropods
- mollusks
- Plant Foods
- leaves
- seeds, grains, and nuts
- fruit
Predation
Anti-predator behavior in this species includes adults distracting predators from
their nests by pretending to be injured. Another behavior includes stretching their
wings out from their body in order to look bigger and frighten predators away. These
warblers are very cautious of intruders and predators and will retreat and skulk into
dense shrubbery if they detect one. These birds may respond to intruders and predators
near their nests by making scolding calls, which can last up to 30 minutes. The kinds
of predators and the manner of predation have not been identified.
Ecosystem Roles
Connecticut warblers are victims of brood parasitism by
brown-headed cowbirds
. The extent of this parasitism still requires study. Other ecosystem roles of this
species need to be studied.
- brown-head cowbirds ( Molothrus ater )
Economic Importance for Humans: Positive
Connecticut warblers are not known to provide any benefits to humans.
Economic Importance for Humans: Negative
There are no known negative effects of Connecticut warblers on humans.
Conservation Status
The conservation status of Connecticut warblers is of least concern, although populations
are declining. The population size is large enough and is not declining at a rate
fast enough to be considered a vulnerable species. Populations may be declining due
to over-collecting, as well as habitat loss including forest fragmentation. Conservation
methods have not been established due to their conservation status.
Additional Links
Contributors
Meher Ahmed (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- bog
-
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- female parental care
-
parental care is carried out by females
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- solitary
-
lives alone
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- acoustic
-
uses sound to communicate
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- frugivore
-
an animal that mainly eats fruit
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
Bent, A. 1963. Life Histories of North American Wood Warblers . New York: Dover Publications, Inc.
Chapman, F. 1907. The Warblers of North America . New York: D. Appleton and Company.
Cooper, J., S. Beauchesne. 2004. "Connecticut Warbler" (On-line pdf). Accessed March 06, 2014 at http://www.env.gov.bc.ca/wld/frpa/iwms/documents/Birds/b_connecticutwarbler.pdf .
Curson, J., D. Quinn, D. Beadle. 1994. Warblers of the Americas . New York: Houghton Mifflin Company.
Harrison, H. 1984. Wood Warblers' World . New York: Simon and Schuster.
Pitocchelli, J., J. Bouchie, D. Jones. 1997. Connecticut Warbler. The Birds of North America , 320: 1-16.
Pitocchelli, J., J. Jones, D. Jones, J. Bouchie. 2012. "The Birds of North America Online" (On-line). Connecticut Warbler ( Oporornis agilis ). Accessed July 25, 2014 at http://bna.birds.cornell.edu.proxy.lib.umich.edu/bna/species/320 .
Verner, J., M. Willson. 1966. The Influence of Habitats on Mating Systems of North American Passerine Birds. Ecological , 47/1: 143-147. Accessed May 05, 2014 at http://www.jstor.org/stable/1935753 .