Conserve Ontario's Carolinian Forests: preserve songbird species at risk, chapter 2

A Closer Look at these Carolinian Forest Songbirds

All five of these songbird species are considered ‘area-sensitive’, which means they are more likely to be found within large, mature forests (forests with a high density of large trees) during the nesting season. Prior to European settlement, the dominant land cover in southern Ontario was forest and it is estimated that the majority of it was mature (Ontario Ministry of Natural Resources 2011). Today, in Ontario’s Carolinian Zone, forest cover ranges from 5% to 25% with mature forest habitat and older growth conditions diminished in both stand size and overall availability.

Each of these five species is a habitat specialist, requiring forest microhabitats with certain characteristics, and four of the five species are listed as a species at risk both provincially under the Endangered Species Act, 2007 (ESA) and federally under the Species at Risk Act (SARA)^Footnote1.

Acadian Flycatchers (Endangered under ESA and SARA) are olive-coloured birds with a light eye ring and two white wing bars. They make their homes under tall, closed tree canopies in the dark interiors of mature woodlands, often along steep-sided ravines. These small birds have an explosive song that sounds like “peet-sah,” which may be heard from shady spots along creeks and swamps. Their nests are generally built at heights of 3 to 9 metres over bare, open areas such as streams and pools of water. Nests are typically suspended from the horizontal branches of American beech, eastern hemlock and flowering dogwood trees, and can be distinguished by long, hanging strands of grass or other materials. Although the Canadian population appears to be relatively stable, there are only an estimated 35 to 50 pairs annually, occupying fewer than 50 sites each year. Acadian Flycatchers are common in many large forests in the eastern and southeastern United States, although the continental population has experienced a decline in recent decades.

Cerulean Warblers (Special Concern under SARA; Threatened under ESA) are distinctively sky-blue (in the case of the male) or blue-green (in the case of the female) on their heads, backs and tails; both sexes have two prominent white wing-bars and white tailspots. Preferring mature deciduous forests with an open understory, male Cerulean Warblers sing a buzzy song from high in the canopy. Their small, tidy, cup-like nests are usually located on high horizontal branches in tall deciduous trees, often near water. The species has experienced widespread declines across much of its North American range. The Canadian population is estimated to be approximately 500 breeding pairs, primarily found within two Ontario regions: the Carolinian Forest and the Great Lakes-St. Lawrence Forest. Population declines are most pronounced in the Carolinian Zone.

Hooded Warblers (Threatened under SARA)are easily identified by their bright yellow faces and underbodies. The males have full black hoods, whereas the females may have nearly complete hoods or no hoods at all. Their loud song suggests the phrase “weeta-weeta-weetee-o.” The nest, best described as a bulky mass of dry leaves, is built in the low, shrubby understory that occurs in small gaps created by natural windfall or selective logging in mature, dry forests. This species prefers to nest close to the ground, often in wild red raspberry (Rubus idaeus) and black raspberry (Rubus occidentalis) thickets. Although the Canadian population is increasing, there are just over 400 pairs (approximately 1000 to 2000 adults) thought to be present in Ontario each year. Hooded Warblers are common in highly forested regions of the eastern and southeastern United States, but are considered to be at risk in several states (Delaware, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, New Jersey, Oklahoma, Rhode Island, and Wisconsin) due to habitat loss and degradation.

Louisiana Waterthrushes (Special Concern under ESA and SARA) are relatively plain, brown warblers with dark streaking on their white underbodies and sides. They can be distinguished from their Northern Waterthrush relatives by a white eyebrow stripe. Louisiana Waterthrushes inhabit a particularly specialized habitat: pristine, steep-sided, headwater stream valleys and associated wetlands in large mature forests. Their song is led by loud, descending whistles that are followed by a complex series of whistled phrases. Louisiana Waterthrushes spend most of their time on or near the ground, where they forage in streams and pools, and nest amongst the roots of fallen trees, in or under fallen logs, or in hollows along stream banks. Nests are generally well-concealed by roots and hanging vegetation. Population levels in Ontario (estimated at less than 200 pairs), where surveys have been conducted in Canada, have remained relatively constant over the past two decades. Despite being fairly common and widespread in parts of the eastern United States, Louisiana Waterthrushes are at risk in some states neighbouring Canada as well as in Quebec. In Canada, the species’ well-being is threatened by woodland loss and degradation, and activities that can degrade water quality such as the use of off-road vehicles to cross rivers and streams which increases stream siltation, alters the aquatic invertebrate community and may reduce food availability for both adult and young birds.

Prothonotary Warblers (Endangered under ESA and SARA) have striking golden-yellow heads and underbodies, with olive-green backs and blue-grey wings and tails. Their loud calls of “tsweet-tsweet-tsweet-tsweet” may be heard in mature and mid-aged deciduous swamps and riparian floodplains with permanent or semi-permanent pools of water. Prothonotary Warblers nest in natural cavities or human-made nesting boxes usually located at heights of 2 metres over still or slow-moving water. Their Canadian and continental populations have declined substantially in recent decades. Ontario currently supports approximately 10 pairs, which is down from more than 40 pairs during the mid-1980s. Although the species is considered secure in many states, the species is considered at risk in all of the states bordering its Canadian distribution (i.e., New York, Pennsylvania, Ohio and Michigan).  

Protecting the populations of these five species in Canada is contingent on conserving the remaining Carolinian forests in Ontario. It is expected that the conservation of Ontario’s Carolinian forests will benefit other forest birds as well, including more common forest species such as the Wood Thrush (Hylocichla mustelina), Ovenbird (Seiurus aurocapillus) and Pileated Woodpecker (Dryocopus pileatus). To protect and enhance the habitat of these songbirds, co-operative efforts are required from landowners, managers, foresters, biologists, planners, municipalities, habitat restoration groups, and community conservation groups.