In January 2020, aerial surveys were successfully conducted of the population of rufa Red Knot Calidris canutus that “winters” in Tierra del Fuego, South America. This year’s surveys revealed a total of 11,795 birds. As recently as 2000, the population numbered over 50,000, but during the following decade it crashed to around 10,000 birds by January 2011. Since then, the annual survey total has varied between 10,000 and 14,000, with a lowest-ever count of 9,840 birds in January 2018.
While it is positive news that there has not been another major decrease, neither has there been any indication of recovery in the population. Prior to this year’s surveys, observations of knots on southward migration in eastern Canada suggested numbers of both adult and juvenile knots were very low (Y. Aubry pers. comm. to G. Morrison). This situation is likely reflected in the lower numbers of knots in Tierra del Fuego compared to 2019 and may reflect low reproductive success in the Arctic during the summer of 2019. Preliminary reports of conditions in the Arctic suggest a warm and windy season with few insects (Y. Aubry pers. comm. to G. Morrison), indicating breeding may have been affected by poor feeding conditions.
The survey aircraft (Piper Archer) used for aerial survey on 16 January 2020. Dr. R.I.G. Morrison (center) with survey participants Gabriel Barreto (left) and Maria Laura Flotron (right) from the Tierra del Fuego Dirección de Áreas Protegidas y Biodiversidad. Photo credit: Santiago de Larminat.
In recent years nearly all of the Red Knot counted during the annual aerial surveys have been found in Bahía Lomas, Chile, a WHSRN Site of Hemispheric Importance and a Ramsar Site. And 2020 was no different: Of the total of 11,795 knot, 11,545 (97.9%) were recorded in Bahía Lomas. No Red Knot were recorded during the aerial survey of the Atlantic Coast of Tierra del Fuego, Argentina (another WHSRN Site of Hemispheric Importance), though 250 birds were recorded in two areas during concurrent ground surveys. The Atlantic Coast was once the other major wintering area in Tierra del Fuego, with counts in the range of 3,500 to 5,000 birds as recently as 2008, but numbers have fallen drastically since then.
The concentration of nearly all the Red Knot in one location (Bahía Lomas) makes them particularly vulnerable to any environmental problems that might occur locally. Fortunately, in January 2019 the Chilean Government declared Bahía Lomas as a Nature Sanctuary (with the official decree signed by the President in April 2020), and the Centro Bahía Lomas from the Universidad Santo Tomás is now leading the development of a management plan for the sanctuary, thanks to support from the BAND, Bobolink, and National Fish and Wildlife Foundations.
Bahía Lomas and Bahía San Sebastián (part of the Atlantic Coast of Tierra del Fuego) are also major wintering areas for Hudsonian Godwit Limosa haemastica. The total of 39,530 godwits counted between the two bays (16,930 and 22,500 respectively) is close to the maximum count recorded in recent years, but still lower than the numbers recorded in the early 2000s, suggesting a long-term decline in the population that “winters” in Tierra del Fuego.
Survey team for Bahía Lomas flight, 13 January 2020: Sr. Antonio Larrea (left, photographer), Capt. Francisco Esquivel (pilot, centre) and Ricardo Matus (right, surveyor) are shown in front of the Eurocopter EC135 helicopter used for the survey. Photo credit: Antonio Larrea.
The annual aerial survey in Tierra del Fuego is a key metric for assessing the recovery and success of conservation efforts for the Red Knot, and for tracking the health of other shorebird populations such as Hudsonian Godwit, and other species considered as conservation priorities for Bahía Lomas. The work in 2020 was specifically designed to develop methods to help ensure compatibility of results from future surveys with those from previous years. This included separate surveys being conducted by two observers (Guy Morrison and Ricardo Matus), and an increased emphasis on obtaining photographs of flocks encountered during the flights to enable comparison of field estimates with counts from photographs and comparison of results from the two observers.
The 2020 surveys in Chile were conducted by Guy Morrison, Ricardo Matus and Antonio Larrea in a helicopter piloted by Francisco Esquivel (survey 1) and Francisco Magini (survey 2), provided by the Empresa Nacional de Petróleo (ENAP) as part of a collaboration agreement with the Centro Bahía Lomas; and in Argentina by Guy Morrison, Gabriel Barreto and María Laura Flotron in a plane piloted by Santiago de Larminat. The surveys were made possible thanks to generous support from Marianne and Jim Welch to Manomet, Inc., and support provided through the International Conservation Fund of Canada. Yves Aubry, Environment and Climate Change Canada, was instrumental in helping to secure support. Special thanks to Carmen Espoz (Santo Tomas University, Santiago) who facilitated arrangements for the surveys in Chile, and ENAP for providing the helicopter. And to Maria Luisa Carranza, Soraya Acardi and Gabriel Barreto, Áreas Protegidas y Biodiversidad, Secretario de Desarrollo Sustenable y Ambiente, Provincia de Tierra del Fuego, Antartida e Islas del Atlantico Sur, for assistance with and very efficient issue of the permit in Argentina. Tabaré Barreto helped with arrangements for the work in Rio Grande.
For more information, please contact Guy Morrison (rigmorrison@gmail.com)
