Wilson´s Phalarope

This taxon displays a slender and elegant morphology, characterized by a long, needle-like black bill that is highly adapted for capturing small aquatic invertebrates. It measures between 8.7 and 9.4 inches in length, with a wingspan of 13.8 to 16.9 inches. The species is famous for its striking reversed sexual dimorphism, where females are larger and more brightly colored during the breeding season. In breeding plumage, the female features a bluish-gray crown and back, a prominent black stripe running from the eye down the neck, which transitions into a rich chestnut-rufous hue on the neck sides and upper breast. Males exhibit a much duller, cryptic plumage dominated by brown and grayish tones. During the non-breeding season, both sexes share a uniform appearance consisting of pale gray upperparts and pure white underparts, retaining only a faint dark line behind the eye. Their long legs are typically yellowish to dark gray, and they possess lobed toes rather than webbed feet, allowing them to swim with great agility.

Geographical distribution: Breeding occurs across the interior prairies of North America, spanning from southern Canada through the western and central regions of the United States. Following the breeding cycle, it undertakes an extraordinary long-distance migration to the Southern Hemisphere. Its primary wintering grounds are located in South America, where it concentrates in immense numbers within the high-altitude wetlands of the Andes and lowland saline basins across Argentina, Bolivia, Chile, and Peru, with vital concentrations documented at Mar Chiquita Lake and various altiplanic salt flats.

Habitat: During the nesting season, it is strongly associated with shallow freshwater wetlands, marshes, wet meadows, and prairie potholes. During migration and the non-breeding period, its habitat preferences shift dramatically toward hypersaline and alkaline lakes. These extreme aquatic environments provide immense concentrations of specialized prey. To a lesser extent, it can also be found in coastal estuaries, mudflats, and wastewater treatment lagoons.

Feeding: The diet is highly carnivorous, composed almost exclusively of aquatic invertebrates. It feeds heavily on brine flies, brine shrimp, midge larvae, and various aquatic beetles. To capture its prey, it employs a highly specialized foraging behavior: it spins rapidly in circles on the water´s surface, creating a miniature whirlpool vortex that pulls benthic invertebrates up into the water column, allowing the bird to pluck them easily with its fine bill.

Behavior: Extremely gregarious, it forms massive flocks that can number in the hundreds of thousands during migration. It is famous for its reversed sex roles; females aggressively court males, defend breeding territories through aerial displays, and may practice sequential polyandry. Their flight is swift and direct, and unlike most other shorebirds, they spend a significant portion of their time swimming actively in open water rather than wading along the shoreline.

Nesting: The nesting cycle is initiated by the courtship displays of the female. Once a bond is formed, the nest is built on the ground, well-hidden among dense shoreline vegetation. It consists of a shallow scrape lined with dry grasses. The female typically lays 4 buff-colored eggs blotched with dark brown. Immediately after the clutch is complete, the female deserts the nest to search for another mate or begin her southward migration, leaving the male to perform all incubation duties for 18 to 21 days. The precocial chicks hatch fully feathered and leave the nest within hours, foraging independently under the sole protection of the male.

Conservation status: It is currently classified as Least Concern (LC) on the IUCN Red List due to its extensive range and large global population. Nonetheless, its long-term survival is threatened by the ongoing degradation of key saline lakes throughout its migratory corridor, driven by water diversion for agriculture, lithium extraction in Andean salt flats, and the severe impacts of climate change on arid-land wetlands.