 |
 YELLOW-BREASTED
CHAT
Icteria virens auricollis
Family Parulidae - Wood Warblers
Order Passeriformes
Risk Status
Official status
The Yellow-breasted Chat is on the British Columbia Wildlife Branch
1993 Red List
(CDC = G5 S1S2) of candidate species to be considered
for legal designation under the Act as Endangered or Threatened.
COSEWIC
assigned a Endangered status in 2000. It is also
protected under the federal Migratory Birds Convention Act
of 1994 as well as the British Columbia Wildlife Act of
1982.
Image Credits: photo by Steve R.
Cannings
Distinguishing features
The Yellow-breasted Chat, a member of the family Emberizidae,
is about 18 cm in length (very large for a warbler) with a bright
yellow throat and breast and white "spectacles". The two
subspecies found in Canada can be distinguished by their appearance.
The Western Chat, Icteria virens auricollis, has more greyish
upper parts, the white of the malar
region is more extended, the yellow of the under parts is deeper,
and the wings, tail, and bill are longer than those of the eastern
subspecies, Icteria virens virens.
The Yellow-breasted Chat is a bird more often heard than seen
since it is usually hidden in brushy riparian tangles or hillside
thickets. Its loud whistles, chatters and squawks make it easy to
identify. It will often sing at night, and the voice is the lowest-pitched
of any of the North American wood warblers. Besides being much larger
than other wood warblers, it also has unique characteristics (holding
its food with its foot, having a distinct song and aerial courtship
displays, develops no natal down, and is the only warbler that has
a complete post-juvenile moult.)
The Yellow-breasted Chat that breeds in the Thompson-Okanagan
region has a few common names. It was formerly known as the Long-tailed
Chat, but now is referred to as the Western Yellow-breasted Chat
(Icteria virens auricollis).
Distribution
Map
Red dots indicate specimen records or confirmed breeding sites.
British Columbia
In British Columbia, the Yellow-breasted Chat is restricted to the
valley bottoms of the south Okanagan and Similkameen valleys from
Vaseux Lake and Cawston, southward to the International border.
Almost all known sightings or nest records are located along the
Okanagan and Similkameen rivers mainstem rather than in side valleys.
Outside that area there is only one breeding record and 15 sight
records, mostly of singing males. In the Thompson-Okanagan they
are locally common in a few remaining habitat patches (River Road,
Oliver; Okanagan River oxbows from Oliver to Osoyoos Lake) but are
rare elsewhere. Museum records indicate that the Yellow-breasted
Chat has been sighted on Vancouver Island, Kamloops, Armstrong,
Chase, and Merritt, and as far north as Clinton in the interior.
North America
There are two subspecies, the Western Yellow-breasted Chat, Icteria
virens auricollis which breeds in the southern parts of Alberta,
Saskatchewan and British Columbia, from the Great Plains west to
the Pacific coast, and from southern British Columbia south to the
tableland of Mexico and Baja California. The eastern subspecies,
I. v. virens, breeds in southern Ontario and is casual in
New Brunswick, Nova Scotia, and Newfoundland. In the United States,
the Eastern Yellow-breasted Chat breeds from North Dakota, southern
Minnesota, southern Wisconsin, southern Michigan, central New York,
southern Vermont and southern New Hampshire, south to south-central
Baja California, Jalisco, the state of Mexico, southern Tamaulipas,
the Gulf states and northern Florida, and winter from Mexico and
southern Texas south to western Panama.
Despite being the same subspecies as on the prairies, the Western
Yellow-breasted Chat in British Columbia occupies a separate biogeographic
area and is treated separately in wildlife conservation. The Ontario
population also is treated separately in Canadian legislation, since
it is a separate subspecies from those out west.
Habitat
The Yellow-breasted Chat is a bird of "edge habitat"
where forests meet clearings, along fencerows, dense thickets and
brambles in low wet places near streams, pond edges, or swamps and
in old overgrown clearings and fields. It nests in small trees such
as trembling aspen, saplings or bushy tangles, favouring wild rose,
hawthorn and snowberry thickets, but they also use elderberry and
saskatoon bushes.
What appears to be important for good chat habitat are areas of
impenetrable thickets with few small trees; it is not a bird of
older forests or woodlands. In fact, it often is associated with
the early successional stages of forest regeneration, living close
to human habitation.
Why is it endangered?
Yellow-breasted Chat habitat is protected in the Vaseux-Bighorn
National Wildlife Area, Inkaneep Provincial Park, and the Osoyoos
Oxbows Wildlife Management Area. Although no data are available,
the amount of suitable habitat for chats in British Columbia has
almost surely declined considerably in this century.
The lowland riparian thickets favoured by chats usually are cleared
for agricultural and residential/industrial developments. There
now seem to be only five sites remaining in the province that are
suitable for breeding: 1) the south Similkameen Valley, which probably
contains the most extensive habitat in the province; 2) Okanagan
River oxbows at north end of Osoyoos Lake; 3) Okanagan River between
Inkaneep Provincial Park and McIntyre Bluff; 4) Vaseux Lake, primarily
at the north end but previously at the south end, as well; and 5)
woodlands along the Okanagan River on the Penticton Aboriginal Reserve.
Western Yellow-breasted Chat that establish territories next to
farmlands, particularly orchards, may be affected by pesticide applications
either indirectly (through loss of insect food) or directly (through
direct contact with pesticides).
Brown-headed Cowbird parasitism
Western Yellow-breasted Chat nest; cowbird eggs occurred in 3 of
14 chat nests found in the Okanagan Valley in one study. The impact
of brood-parasitism on chats may be fairly light, because they can
apparently successfully raise most of their own nestlings as well
as the young cowbird.
Because chats are secretive and shy, nest sites are difficult
to find, and thus, direct human disturbance is uncommon. However,
indirect disturbance (from habitat destruction, and agricultural
activity) may be a serious threat to the Western Yellow-breasted
Chat. The Yellow-breasted Chat is not particularly susceptible to
grass or brushfires, fluctuating water levels, severe winters, or
wet or dry seasons, but chats are impacted by cold weather and other
conditions that affect insect populations.
Biology
Breeding
Western Yellow-breasted Chats nest from mid-May to the third week
of June. The females incubate 3-5 eggs for approximately 11 days.
Incubation, conducted
entirely by the female, takes 11 to 15 days, and the female broods
the nestlings. Both parents feed the young, and the nestlings fledge
after 8 to 11 days. In the Okanagan Valley of British Columbia,
most clutches are initiated in the second week of June, with dates
ranging from May 12 to June 23, suggesting that Western Yellow-breasted
Chats could raise a second brood if the season is sufficiently long.
The nests are large and bulky, but well-concealed. Cup-shaped
nests are composed of coarse materials like leaves, shreds of bark,
coarse straws and weed stalks and lined with fine grasses, and are
located low in dense bushes, usually not more than a metre from
the ground. Most nests are impossible to investigate (or locate)
due to their placement in thick thorn scrub and dense thickets.
Since only thirteen chat nests have been reported from British
Columbia, we know little about their breeding success. Hatching
success is known for two nests; in both of them one egg of the clutch
failed to hatch. Reports state that fledging brood sizes range from
one to two young, so it is estimated that breeding success rate
is about 48%.
Behaviour
The Western Yellow-breasted Chat is fairly well-known to bird watchers,
but its secretive habits make it difficult to observe. The species
is vocal with a distinctive and loud song or chatter. Chats are
conspicuous when singing, and usually birds are found by following
its call. The male often sings at night, usually from a low perch
encased by thick shrubbery, and it sometimes seems to mimic the
songs of other species.
The Yellow-breasted Chat usually is monogamous.
Sometimes they will nest in groups or "colonies" but each
pair forms separate territories. A study in Indiana, found males
either formed pair-bonds with a succession of females in one season,
remained paired to one female the entire time they were on the study
area, or were for a time paired to one female and for a time unpaired;
only one male exhibited polygyny.
However, nesting success apparently had a profound effect on the
stability of the pair bond. Pairs that experienced no nest failure
in a particular breeding season remained together throughout the
season, and about 50% of males that experienced nest failure bred
with new mates in subsequent seasons.
Chats are migratory and usually return to the Okanagan around
the third week of May. There are a few records after mid-July, when
young birds have fledged, and most birds leave BC by mid-August.
The Western Yellow-breasted Chat winters from southern Baja, southern
Sinaloa, southern Texas and southern Florida, south through Central
America to western Panama. There is little information regarding
the species on its wintering grounds. They head north to breed by
about the middle of April.
Like other small passerine species, the Yellow-breasted Chat matures
in one year and generally has a short life span, but the longevity
record is eight years, 11 months.
Diet or Growing requirements
During the breeding season, the Yellow-breasted Chat's diet consists
mainly of insects such as weevils, and other beetles, ants, moths,
bees, wasps, mayflies and caterpillars. Berries (including wild
strawberries, grapes, blackberries, raspberries, whortleberries,
and elderberries) make up a large portion of its diet in late summer.
Young are fed only insects. The main method of obtaining food during
the breeding season is gleaning
from plant foliage and occasionally from branches, and although
both the male and female are foliage gleaners, female also look
for food lower in the shrubbery and on the ground.
Predators
From studies of breeding success of Yellow-breasted Chat nests in
Indiana, the major causes of breeding failure was egg predation,
primarily by snakes. Blue jays, chipmunks and brown-headed cowbirds
also predated nests in the studies.
Sources for more
information
Related On-line Sites to Visit
Publications
Status Report - Wildlife Bulletin No. B-81, March 1995, R.J.
Cannings
Status Report - COSEWIC, Cadman and Page, 1994
Birds of the Okanagan Valley, Cannings, 1987, p. 334
Habitat Conservation Fund , August 1992
Hlady, D.A. 1990. South Okanagan Conservation Strategy: 1990-1995.
B.C. Ministry of Environment, Victoria, B.C.
Museum Specimens
this section sponsored
by: 
Industry Canada
|
