Blackpoll Warblers breed in black spruce and tamarack forests in Canada's boreal forests. In western Canada, they also use thickets of spruce, alder, and willow. In northern New England they breed in wet areas with evergreen trees. During migration they stop over in scrubby thickets and mature evergreen and deciduous forests. On their wintering grounds east of the Andes in South America, they occur in forest edges and second-growth forests below 10,000 feet. Back to top
Blackpoll Warblers eat mainly spiders and insects such as caterpillars, gnats, lice, ants, beetles, mosquitoes, and flies. They tend to forage at eye level and above, picking insects off the branches of evergreen and deciduous trees and shrubs. During fall migration they also eat fruit including honeysuckle, pokeberry, and yew. Back to top
The female moves among spruce and fir trees looking for a place to nest. She tries out different spots as if she were building a nest, but without adding any nesting material. The spot she chooses is usually near the trunk of a spruce or fir tree. Nest height ranges from 0.5–30 feet above the ground.
The female builds a cup-shaped nest out of twigs and lichen. She shapes the inner cup with her body, twisting from side to side until the finer grasses and hair used to line the nest are in place. It takes her about 3–4 days to complete a nest. The outside of the nest is about 4 inches across and 2.5 inches tall. The inner cup is about 2 inches across and 1 inch deep.
|Clutch Size:||3-5 eggs|
|Number of Broods:||1-2 broods|
|Egg Length:||0.7-0.8 in (1.7-2 cm)|
|Egg Width:||0.5-0.6 in (1.2-1.5 cm)|
|Incubation Period:||11-12 days|
|Nestling Period:||8-10 days|
|Egg Description:||Whitish to pale green with brown and purplish blotches around the larger end.|
|Condition at Hatching:||Naked and helpless with closed eyes.|
Blackpoll Warblers move slowly along branches in evergreen trees looking for insects. They tend to forage primarily from eye level up to the canopy in the interior branches of evergreen trees, especially during the summer in their northern range. Males start singing during spring migration and continue to sing from high perches at all hours of the day on the breeding grounds. In the spring, males arrive north before females and almost immediately start setting up their territories. Females arrive 2–3 days later, forming a pair with a male soon after. Males follow females closely while they are building the nest and laying eggs. Males and females maintain their bond typically only during the breeding season, but some return to breed with the same mates in the following year. Although mostly monogamous some males breed with more than one female. During the breeding season they are generally solitary, but join mixed-species flocks during the nonbreeding season. Back to top
Blackpoll Warblers are numerous throughout their range, but their numbers have declined severely in recent decades. Much of their far-northern breeding range lies outside of the area covered by the North American Breeding Bird Survey, making it hard to estimate population trends precisely. Nevertheless, North American Breeding Bird Survey records suggest an extreme decline of over 2% per year for a cumulative decline of 71% from 1966 to 2019. Partners in Flight estimates a global breeding population of 60 million and rates them 11 out of 20 on the Continental Concern Score. Despite their numbers, Blackpoll Warbler is listed as a Common Bird in Steep Decline for species that are still too numerous or widely distributed to warrant Watch List status, but have been experiencing troubling long-term declines. Partners in Flight estimates that if current trends continue, an additional 50% of the Blackpoll Warbler population will be lost in as little as 16 years. Although the remote boreal forest regions where Blackpoll Warblers breed are still relatively intact, logging and extractive industries are rapidly expanding and threatened warbler habitat. More than 180 million acres of the boreal forest has been impacted by extractive industries. In the long-term, the boreal forest is also vulnerable to climate change. On the wintering grounds in South America, Blackpoll Warblers are vulnerable to habitat loss. During their epic transoceanic journey to wintering grounds in the far north, they face bad weather that can make passage difficult, urban lights that confuse migrating birds, and lighted towers. In one day in Florida, 586 Blackpolls died after striking a tower.Back to top
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