The tiny, delicate, beautiful azure Cerulean Warbler is vulnerable to extinction in both its summer and winter homes. Although adults are only about four inches (10 cm) long they fly from Central Canada and the Appalachian Mountains in the United States to the Andes in Columbia, Venezuela, and Peru, once winter comes.
They have been declared endangered in Canada, and in Colombia, 545 acres have been set aside for the Cerulean Warbler Bird Reserve. Their numbers are thought to have declined by more than 70 percent since 1970.
They live in the tops of soft maple, birch, oak, basswood, linden, elm, sycamore, or black ash trees. In Canada and the United States, their habitat has been fragmented by urban development and the removal of old-growth forests. While in South America, non-traditional farming methods have led to fewer tall trees for the birds. Coffee plantations have been developed and mechanized, and trees have been removed. Previously, traditional coffee farming methods allowed for shade-grown coffee planting.
Cerulean Warbler parents build little, cup-shaped nests from bark, spider webs, grass, weeds, moss, and lichen, 15 to 90 ft (4.5- 27.5m) up. As many as five small 2 cm (3/4 in) eggs are found in their nests, and hatch about two weeks after they are laid. Chicks are born blind–without feathers–and are aggressively protected by their parents; who, at times, get in tussles with other birds.
Cerulean Warblers primarily eat insects and nectar, although they have been seen eating vegetation in winter. They are also known for jumping from branches sometimes, with their wings folded up, only to open them when they are far below their nests. It has been called bungee jumping for birds, and disguises nest locations from lurking predators.
These blue birds are hard to see from below the forest canopy, so Cerulean Warblers are identified from below by their thin pointed bills, two white wing bars, and white spots on their tails.
Brown-headed Cowbirds have also been known to harm Cerulean Warbler numbers. They add eggs to a clutch in a Warbler nest, and once the impersonator chicks hatch, the Cerulean Warbler parents dutifully feed them. Then the brown-head cowbird chicks outgrow, attack, and starve out the Cerulean Warbler chicks.
The US Fish and Wildlife Service reports that the Cerulean Warbler Appalachian Forestland Enhancement Project, centered on Maryland, Kentucky, Ohio, West Virginia, and Pennsylvania, has earmarked approximately $8 million to assist with forest regeneration on private lands.
Historically the area woodlands have been mismanaged, and the Appalachian project sees the monies are spent on invasive plant removal, weed thinning, and tree planting. A total of about 1,100 acres damaged by old mines are part of a reclamation plan. The American Bird Conservancy is involved, as well as the Appalachian Mountains Joint Venture.
The American Bird Conservancy is also aboard for the central Colombian Cerulean Warbler Bird Reserve, near Bucaramanga. A small shade-grown coffee plantation is included, and it incorporates trees friendly to Cerulean Warblers. It totals 37 acres, and the shade-grown coffee is sold as a Cerulean Warbler-friendly product. The proceeds partially fund the “La Reserva Natural de las Aves Reinita Cielo Azul”.
Established in 2005, the non-profit group, Fundación ProAves, is a prime mover in the Cerulean Warbler Bird Reserve. Other species who benefit from the project include: hummingbirds, grackles, quail, parrots, foxes, and spectacled bears. For anyone who plans to visit the rugged area, there is a lodge 20 minutes away from the park in San Vicente.
Cerulean Warbler. The American Bird Conservancy. (2021, October 8). https://abcbirds.org/bird/cerulean-warbler/
Species Conservation Profiles: Cerulean Warbler. Partners in Flight. (2021). https://partnersinflight.org/species/14179/
Cerulean Warbler Bird Reserve. Wikipedia. (2021, January 9). https://en.wikipedia.org/wiki/Cerulean_warbler
Cerulean Warbler Life History. Cornell University. (2019). https://www.allaboutbirds.org/guide/Cerulean_Warbler/lifehistory
Species of Concern: Cerulean Warbler (Dendroica cerula) Fact Sheet. U.S. Fish and Wildlife Service. (2020, January 2). https://www.fws.gov/midwest/es/soc/birds/cerw/cerw-fctsheet.html
Cerulean warbler. Wikipedia. (2021, November 13). https://en.wikipedia.org/wiki/Cerulean_warbler
Cerulean warbler. The Nature Conservancy of Canada. (2020). https://www.natureconservancy.ca/en/what-we-do/resource-centre/featured-species/birds/cerulean-warbler.html
Cerulean Warbler. Natural Resources Conservation Service Pennsylvania. United States Department of Agriculture. (2021). https://www.nrcs.usda.gov/wps/portal/nrcs/detail/pa/programs/farmbill/rcpp/?cid=nrcseprd888823
Cerulean warbler. Ministry of the Environment, Conservation, and Parks, Government of Ontario. (2021, August 12). https://www.ontario.ca/page/cerulean-warbler
Cerulean Warbler. National Audubon Society. (2021). https://www.audubon.org/field-guide/bird/cerulean-warbler