The Whimbrel (Numenius phaeopus) is a large shorebird that breeds in subarctic areas and migrates long distances to wintering grounds. Understanding where Whimbrels breed is important for conserving their populations. This article will examine the major breeding areas for Whimbrels across their range.
Breeding in North America
In North America, Whimbrels breed primarily in subarctic and boreal forest areas in Alaska, Canada, and the eastern Canadian Maritimes. Their breeding range extends from northwestern Alaska across northern Canada to the Hudson Bay lowlands and the coasts of Labrador and Newfoundland.
Some key breeding areas for Whimbrels in North America include:
- The Yukon-Kuskokwim Delta in southwestern Alaska
- The North Slope of Alaska
- The Mackenzie River Delta in the Northwest Territories
- Hudson Bay lowlands in northern Manitoba and Ontario
- Coastal areas of southern Baffin Island
- Northern Labrador and the Quebec-Labrador Peninsula
- Insular Newfoundland and the Maritime provinces
The total North American breeding population of Whimbrels is estimated at around 166,000 birds. Alaska supports the largest share of the breeding Whimbrels, followed by the central Canadian Arctic and Hudson Bay region.
Breeding in Eurasia
In Eurasia, Whimbrels nest across a broad swath of the subarctic region from Fennoscandia east across Russia to the Chukotka Peninsula. Major breeding areas include:
- Northern Finland, Sweden, and Norway
- Northern Russia across the tundra zones
- The Taymyr Peninsula of northern Russia
- The Lena River delta and surrounding areas of northeastern Russia
- The Anadyr lowlands and northern Chukotka in far eastern Russia
The total Eurasian breeding population of Whimbrels is estimated at around 530,000-600,000 birds. Russia supports the majority of the Eurasian breeding Whimbrels, particularly in the vast stretch of tundra across northern Siberia.
Breeding in the Subantarctic Islands
Whimbrels also breed on subantarctic islands including:
- Iceland
- The Faroe Islands north of Scotland
- Saint Pierre and Miquelon Islands south of Newfoundland
- South Georgia Island
These subpolar island breeding populations are fairly small but make important contributions to the global populations of the species.
Breeding Habitat
Whimbrels breed in various open habitat types across the subarctic region. Their nesting habitats include:
- Coastal wet tundra
- Inland mossy hummock tundra
- Lowland meadows and grasslands
- River deltas
- Coastal heath
- Dwarf shrub habitats
- Open boreal forests and forest-tundra transition zones
Key requirements are open terrain with good visibility, moist or wet soil conditions, and the presence of small mammals, insects and other invertebrates for feeding.
Some details on major breeding habitats:
Coastal Tundra
Along coastlines throughout the Arctic, Whimbrels nest commonly in wet sedge- and grass-dominated tundra. This habitat occurs along the northern and western coasts of Alaska, northern Canada, Greenland, Svalbard, and Arctic Russia. The moist conditions provide abundant food sources.
Inland Tundra
Inland regions of mossy, hummocky tundra also provide good nesting habitat, such as areas along the North Slope of Alaska, the central Canadian Arctic, and the Taimyr Peninsula of Russia. The mosaic of small mounds help conceal nests.
Boreal Forest Fringe
Whimbrels will also nest in open boreal forests, forest-tundra transition zones, and shrublands along the southern edge of the tundra, such as in parts of central Alaska, the Hudson Bay lowlands, and Scandinavia. The mix of small trees, shrubs, and open ground provide cover and foraging areas.
River Deltas
Major river deltas along the Arctic coastline, like the Mackenzie Delta and Lena Delta, provide important nesting habitat. These areas have a rich food supply and a mix of wetland vegetation for nesting.
Subantarctic Island Habitats
On subantarctic islands, Whimbrels nest in coastal heath and grassland habitats, using vegetation like tussock grass for nest concealment. Food sources include invertebrates like earthworms, beetles, and insects.
Breeding Season
The breeding season of Whimbrels varies across their range:
- Alaska: early May to mid-July
- Central/Eastern Canadian Arctic: early June to late July
- Hudson Bay: late May to late July
- Iceland: mid-April to mid-July
- Fennoscandia: mid-May to late June
- Russia: late May to mid-July
The earlier breeding in Iceland and extending into mid-summer in Alaska reflects the wide variation in conditions across the Whimbrel’s range. Peak hatching of chicks occurs in early to mid-June through most regions.
After breeding, Whimbrels undergo a timed molt prior to fall migration. Adults leave first, followed by juveniles a few weeks later once they have fledged and gained flight ability.
Threats and Conservation
Whimbrel populations face a number of threats on their breeding grounds, including:
- Habitat degradation from climate change and sea level rise
- Disturbance and development pressure in some coastal areas
- Predators like foxes, gulls, ravens, and bears in some regions
- Contaminants from industrial development
Conservation priorities for breeding Whimbrels include:
- Protecting habitat in key coastal wetland, upland tundra, and boreal forest fringe sites
- Monitoring and managing predator populations
- Limiting development and human disturbance near breeding areas
- Addressing climate change impacts on arctic ecosystems
International cooperation is needed as Whimbrels cross multiple countries and continents during migration. Maintaining the integrity of breeding and wintering habitats across their full range is crucial for sustaining populations.
Migration Patterns and Wintering Range
After the breeding season, Whimbrels embark on long distance migrations to wintering areas centered in South America. The migration includes:
- North American breeders concentrate along the Atlantic Coast of the US and Maritimes before flying over ocean to northern South America.
- Eurasian breeders stopover in Western Europe before crossing the Atlantic to Africa and eventually South America.
- The birds display a leap-frog pattern, with northern breeders traveling further south than southern breeders.
- Most birds winter in coastal wetlands, rainforests, and agricultural fields from Venezuela to Tierra del Fuego at the southern tip of South America.
The North American subspecies (N.p. hudsonicus) tends to winter further north in northern South America, Central America, and the Caribbean compared to the Eurasian subspecies (N.p. phaeopus) that winters mainly in southern South America.
Migration Stopovers
Key stopover sites used by Whimbrels during migration include:
- North American Atlantic Coast from Labrador to Florida
- Caribbean islands like Guadeloupe and Barbados
- Northern coast of South America including the Guianas and Suriname
- Western Europe from Britain to Iberia
- Mediterranean basin and North Africa
Conserving adequate food resources, roosting habitat, and protection from disturbance at migratory stopovers allows Whimbrels to rest and refuel during their long journeys between breeding and wintering areas.
Major Wintering Regions
The largest concentrations of wintering Whimbrels are found along the north and east coasts of South America including:
- Suriname and French Guiana
- Northeast Brazil
- Southern Brazil
- Uruguay and Argentina
- Chile and southern Peru
Coastal habitats like mangroves, estuaries, and lagoons provide important winter habitat. Agricultural fields also support feeding Whimbrels in many regions.
Conclusions
In conclusion, Whimbrels nest across an extensive area of the northern subarctic region from Alaska to Russia during the short arctic summer. Coastal wet tundra, inland hummock tundra, boreal forest fringes, and river deltas provide the essential open, moist habitat conditions Whimbrels require for breeding.
After breeding, the birds migrate to South America, a journey of up to 14,000 km one-way for some populations. Coastlines along the full length of South America serve as vital wintering areas.
Maintaining high quality breeding areas, stopover sites, and wintering habitats across two continents is critical for the conservation of Whimbrel populations into the future. International cooperation on protecting wetlands and managing disturbance threats is needed to ensure these marathon migrating shorebirds can continue their epic annual journeys across hemispheres.