Translated from the Spanish by the WHSRN Executive Office
Read the story in Portuguese here.
The Red Knot (Calidris canutus) is a species of high conservation concern throughout the Western Hemisphere. During the non-breeding season, the rufa subspecies, which breeds in the central Canadian Arctic and migrates primarily along the Atlantic coast, congregates at sites from the southern United States to Tierra del Fuego in four main regions (southern United States and the Caribbean, western Gulf of Mexico, northern coast of South America, and Tierra del Fuego – Patagonia). The rufa subspecies is listed as threatened with risk of extinction in many countries within its range. To determine the population size of the rufa Red Knot and identify changes in the population, this subspecies is being monitored at several sites in South America.
During the 2023 wintering season, a network of collaborators coordinated by the Executive Office of the Western Hemisphere Shorebird Reserve Network (WHSRN) conducted a simultaneous survey for the rufa Red Knot. The surveys were conducted within a short time window (January 27-29), and included the main sites within their wintering range. This incredible collaboration included Fundación Conservación Marina (Chile), Red de Observadores de Aves y Vida Silvestre de Chile (Chile), Centro Bahía Lomas (Chile) and Asociación Ambiente Sur (Argentina).
The areas that were monitored included the coast of the province of Santa Cruz (Argentina), Tierra del Fuego Atlantic Coast Reserve (Argentina), Bahía Lomas (Chile), and the Lake District (Chile).
Left: Volunteers from various organizations mobilized between 27 and 29 January 2023 to monitor rufa Red Knots at different sites of interest in southern South America. Photo: Asociación Ambiente Sur. Right: rufa Red Knots in nonbreeding plumage. Photo: Diego Luna Quevedo
Santa Cruz (Argentina): Six sites were surveyed along the Atlantic coast of this Argentine province: Gallegos River Estuary, Coyle River Estuary, Santa Cruz River Estuary, Puerto San Julián, San José Dam in Río Turbio, and a sector of Lago Argentino in front of the Laguna Nimez Municipal Nature Reserve. The sites were surveyed on foot, and on January 29th an aerial survey covering the Gallegos River Estuary was conducted to complement the ground surveys.
Tierra del Fuego Atlantic Coast Reserve (Argentina): This site is a coastal strip approximately 220 km long along the coast of the Argentine province of Tierra del Fuego. An aerial survey covering the was conducted here on January 28th.
Bahía Lomas (Chile): This site is located at the eastern mouth of the Strait of Magellan, on the north coast of Tierra del Fuego Island, Magellan and Chilean Antarctica Region. In recent years has hosted almost all of the southernmost population of rufa Red Knot. The monitoring here was two helicopter aerial surveys conducted on January 27th and 28th.
Lakes Region (Chile): The survey focused on 32 sites within this Region, identified as holding important abundances of migratory shorebirds. Several of these sites are WHSRN sites (Humedales de Maullín, Humedal Marino de Coihuín, and Humedales Orientales de Chiloé). Ground surveys were conducted from January 27th-29th with aerial surveys conducted at three sites in the southern area of the Chiloé Archipelago (Aituy, Huildad and Yaldad).
rufa Red Knot in nonbreeding plumage. Photo: Brad Winn
Survey results
The following are the results obtained for abundances of Red Knot at the different sites surveyed.
Santa Cruz: During ground and aerial surveys on the Atlantic coast of this Argentine province, only two individuals of Red Knot were recorded in the town of Puerto San Julián. Both individuals were in non-breeding plumage.
Tierra del Fuego Atlantic Coast Reserve: no Red Knot were recorded during the scheduled aerial survey, although individuals of this species were reported the previous day (January 27th) at the mouth of the San Martín river (41 individuals) and on the beaches of the city of Río Grande (40 individuals).
Bahía Lomas: Due to the quality of the images, the counts of Red Knot were based on the photographs obtained during the January 27 survey. The difference between the counts made by the two experts from the photos obtained was 0.4%. The average abundance of Red Knot was 14,974 ± 27 individuals.
Lakes Region: Red Knot were only recorded in three of the 32 sites surveyed: 11 individuals in Estero Rulo (Calbuco), four individuals in Aucar (Chiloé) and two individuals in Lepihué (Maullín), for a total of 17 individuals recorded in the Region.
Team that participated in the surveys of Bahía Lomas, Chile, on the flights of January 27, 2023. From left to right: Antonio Larrea (photographer), Ricardo Matus (observer 1), Felipe Jaque (pilot), and Heraldo Norambuena (observer 2).
Comparison with Past Records in the Region
The results for the censuses conducted in January 2023 were: 2 individuals on the coasts of Santa Cruz, 17 individuals in the Lake Region and 14,974 individuals in Bahía Lomas, giving a total for the species of 14,993 rufa Red Knots. In January 2022, censuses were conducted for the species in the same areas. The results obtained in these surveys were: 48 individuals on the coasts of Santa Cruz, 219 individuals in the Atlantic Coast Reserve Tierra del Fuego,and 14073 individuals in Bahía Lomas, for a total of 14,340 individuals.
According to the results of the census conducted in January 2022 and 2023, 653 more individuals were recorded during this year’s census. However, it is important to note that the censuses in both years did not cover the same sites nor use the same methodology between seasons.
Censuses have been supported for several years at some of the sites within the non-breeding area of the subspecies. The information collected improves understanding of the status of the subspecies. However, to analyze the population trend of the subspecies it is important to consider historical data obtained during the last two decades in this area.
Analysis of historical abundance data for the Red Knot in Bahía Lomas (from 2000 to 2023) shows a general trend of stabilization of the wintering population from 2005 to the present (10,000-15,000 individuals). The abundance recorded in 2023 is among the highest recorded in the last 10 years. Similar values were obtained in 2012 (14,000 individuals) and 2014 (14,200 individuals) (Norambuena 2023).
Cover Photo: Mixed flock of Red Knots and Hudsonian Godwits recorded during the aerial survey at Bahía Lomas. Photo: Antonio Larrea.
