Record number of Nearctic Shorebirds counted during the 2019 Central American Waterbird Census

The 2019 Central American Waterbird Census (CAWC), coordinated for the third year by the WHSRN Executive Office, covered more sites and counted more waterbirds than any year since the census began in 2011 – specifically, more Nearctic shorebirds were observed than ever before! Between 15 January and 15 February of 2019, 142 volunteers from throughout Central America and southern Mexico visited an astonishing 230 sites and counted a total of 355,260 waterbirds. Nearly half of these (175,760 individuals) were Nearctic shorebirds.

The record high number of Nearctic shorebirds comprised a total of 28 species, including three species considered both resident and Nearctic migrants in Central America (American Oystercatcher Haematopus palliatus, Black-necked Stilt Himantopus mexicanus and Wilson’s Plover Charadrius wilsonia). Especially interesting were four banded American Oystercatchers and one banded Wilson’s Plover. Two of the banded oystercatchers were observed in El Salvador, one of which was banded in 2010 in South Carolina and the other in 2018 in Georgia. Interestingly, the bird from South Carolina was also seen in El Salvador in 2017. The two other banded oystercatchers were seen in Honduras, and were originally banded in North Carolina in 2017 and Florida in 2015. It is still unclear where the Wilson’s Plover seen in El Salvador was originally banded, but it may have come from the Gulf Coast of the United States. Of all Nearctic shorebirds recorded, the most common species were Western Sandpiper Calidris mauri, Semipalmated Sandpiper C. pusilla, Least Sandpiper C. minutilla and Wilson’s Plover. With a combined total of 140,994 individuals, these four species represented 80% of all Nearctic shorebirds counted in this year’s CAWC!

High numbers of Wilson’s Plover revealed ten sites that could qualify as potential WHSRN sites, including eight at the level of Regional Importance, one of International Importance, and one as a possible site of Hemispheric Importance. One of these sites, El Agallito in Panama, appears to be an important wintering site for the species, as significant numbers of Wilson’s Plover were also found there during the CAWC in 2018. The other potential WHSRN sites for Wilson’s Plover were found in Costa Rica (2), El Salvador (3), Honduras (3) and Nicaragua (1). Another species observed in large enough numbers to trigger eligibility as a WHSRN site was the Short-billed Dowitcher Limnodromus griseus (ssp. caurinus), whose numbers reached the 1% threshold for a Site of Regional Importance at Laguna Tisma (Nicaragua) and Punta Morales-Cocorocas Salinas (Costa Rica).