The Cape May warbler is a small songbird that is found in North America during the spring and summer months. It is named after Cape May, New Jersey, which is located along the migration route of these birds. The scientific name for the Cape May warbler is Setophaga tigrina. It belongs to the genus Setophaga, which includes a number of other North American wood-warblers. There are no recognized subspecies of the Cape May warbler.
Physical Description
The Cape May warbler is a relatively small warbler, measuring about 13 cm (5 in) long with a wingspan of 18-23 cm (7-9 in). Males and females have similar plumage, though males tend to be brighter in color. During the breeding season, adult males have chestnut-colored faces and yellow-olive upperparts with bold black streaks. Their underparts are also yellow with black streaks on the sides. Females are duller overall, with an olive-green back and pale yellow underparts. Both sexes have a broken white eye ring and pointed bills.
In the fall and winter months, Cape May warblers undergo a complete molt. Their breeding plumage is replaced by dull greenish-yellow upperparts and pale yellow underparts. They lose the bold black streaks and chestnut facial coloring. First-year birds in the fall resemble adults in their non-breeding plumage. Cape May warblers can be distinguished from other similar warbler species by their sharp, pointed bills and the large white patches on their outer tail feathers.
Distribution and Habitat
The Cape May warbler breeds across Canada and into the northern United States, generally between 45°N and 63°N latitude. Its breeding habitat consists primarily of open coniferous forests, especially those dominated by spruce trees. Cape May warblers rely on the dense cover provided by conifers for nesting and foraging.
During the fall migration, Cape May warblers can be found throughout eastern North America. They primarily migrate along the Atlantic coast, with some inland movement as well. They winter in the Caribbean islands and parts of Central America. Their winter habitat consists of coastal scrub, second growth woods, and forest edges. Cape May warblers are rarely found deep within dense tropical forests during the winter.
Season | Location |
---|---|
Breeding (May – July) | Canada, Northern United States |
Migration (August – October, March – May) | Throughout Eastern North America |
Winter (November – February) | Caribbean, Central America |
Diet and Feeding
The diet of the Cape May warbler consists primarily of insects and other small arthropods. Its thin, pointed bill is well-adapted for picking insects off of foliage and branches. During the breeding season, Cape May warblers forage among the needles and branches of spruce trees searching for spiders, caterpillars, beetles, and other insects. They also glean insects from the leaves of deciduous trees when foraging in mixed forests.
In their winter habitat, Cape May warblers probe flowers and leaf clusters for insects. They are able to hover briefly while picking insects off vegetation. Cape May warblers also supplement their diet with nectar from flowers and occasionally fruit pulp. They are agile foragers, able to catch insects on the wing by making short flights from their perches.
Common Foods Include:
- Caterpillars
- Spiders
- Beetles
- Ants
- Flies
- Aphids
- Moth eggs
- Fruit pulp
- Nectar
Migration
The Cape May warbler is one of the last warblers to migrate north in the spring, not typically arriving on its breeding grounds until early June. In the fall, populations vary in the timing of their southbound migration. Some migrate back to the Caribbean as early as late July, while others remain in northern areas until late September or October.
On their migratory journeys, Cape May warblers stop over in a wide variety of wooded habitats. Preferred stopover sites include areas with fruiting trees and shrubs that provide needed food resources. Cape May warblers often join mixed flocks with other migrating warblers, vireos, and kinglets during migration. These mixed foraging flocks likely provide additional protection from predators.
It is estimated the Cape May warbler travels between 1,500 – 3,000 miles between its breeding and wintering grounds each year. Their migratory routes include major ecological barriers like the Gulf of Mexico and Caribbean Sea, which involve non-stop flights of up to 18-24 hours. Cape May warblers rely on favorable winds and weather patterns to facilitate these long distance journeys.
Breeding and Nesting
Cape May warblers breed in mature coniferous forests across Canada and into the northernmost United States. Nesting usually begins in early June. The female builds a well-hidden cup nest on a horizontal tree bough, often near the trunk. Usual nest locations are 5 to 20 feet above ground.
Cape May warbler nests are constructed from bark strips, twigs, lichens, and lined with softer materials like moss, feathers, and deer hair. The female lays 3-5 eggs which she incubates for 10-12 days. The eggs are creamy white with brown spotting. After hatching, both parents feed the young a diet of insects and other arthropods. Nestlings fledge the nest at 9-12 days old.
Some key aspects of Cape May warbler breeding and nesting:
- Nesting territory is about 1 to 3 acres in size
- Nests are well-hidden on horizontal conifer branches
- Female incubates 3-5 eggs for 10-12 days
- Young leave nest after 9-12 days
- Both parents feed nestlings
Interestingly, male and female Cape May warblers may mate with new partners from year to year. They do not form lasting pair bonds over multiple breeding seasons like many other warbler species. Competition for high quality nesting sites helps drive this annual reshuffling of mates.
Vocalizations
The song of the Cape May warbler is a lively series of 5-10 tchip notes. This distinctive song can be easily recognized as it rings through the breeding habitat. Males sing to establish their nesting territories and attract potential mates. Their song is quicker and more hurried than that of similar species.
Cape May warblers use a variety of call notes as well. A sharp chip serves as an alarm call when danger is detected. A low seet note is given by foraging birds, likely to keep the flock in contact. During aggressive encounters, Cape May warblers give a fast trilling call. Both sexes sing and vocalize.
Here are some key vocalizations of the Cape May warbler:
- Song – Fast series of 5-10 tchip notes
- Alarm call – Sharp chip sound
- Foraging call – Low seet note
- Aggressive call – Fast trilling
The songs and calls of Cape May warblers are most noticeable during their spring arrival on the breeding grounds. Singing is used most heavily early in the breeding season and decreases after females begin incubating eggs.
Conservation Status
According to the IUCN Red List, the Cape May warbler is classified as a species of Least Concern. It has a large breeding range and a global population estimated between 5 to 50 million individuals. Population trends appear to be stable and the Cape May warbler is not currently considered threatened.
Some specific factors related to its conservation status:
- Global population very large – estimated 5 to 50 million
- Population trend appears stable
- No major threats to survival identified
- Classified as Least Concern on IUCN Red List
There are no major conservation initiatives targeted specifically at Cape May warblers. Protecting their preferred breeding habitat of spruce forests will help maintain populations across North America. Continued monitoring is recommended to detect any future population declines that could warrant increased protections.
Fun Facts About the Cape May Warbler
Here are a few interesting and fun facts about the Cape May warbler:
- Gets its name from Cape May, New Jersey located along its migration route
- One of the last warblers to migrate north in spring
- Males and females may mate with new partners each year
- Uses a hover-gleaning technique to pick insects off vegetation
- Has one of the longest migration routes of all warblers
- Travels up to 3,000 miles between breeding and winter grounds
- Females build nests on horizontal branches hidden near tree trunks
- Nestlings can fly short distances at only 9-10 days old
- The Cape May warbler’s song is a very rapid series of tchip notes
- Populations winter in Caribbean islands and Central America
Conclusion
In summary, the Cape May warbler is a small North American songbird named for the New Jersey town along its migratory flyway. It breeds in coniferous forests across Canada and the northern United States. Cape May warblers feed on insects and other arthropods, foraging actively among spruce trees for spiders, caterpillars and other prey. They build concealed cup nests on horizontal branches, in which the female lays 3-5 eggs. After a long southbound migration, Cape May warblers winter in the Caribbean and parts of Central America. Their global population appears stable and they are classified as a species of Least Concern by conservation groups. The Cape May warbler exemplifies the long distance migrations and fascinating natural histories of New World warblers.