Shorebird monitoring at the Gulf of Fonseca: a tri-national approach

In 2016, the Delta del Estero Real in Nicaragua joined the WHSRN network as a Site of International Importance for hosting more than 10% of the beldingi subpopulation of the Wilson’s Plover Charadrius wilsonia. Delta del Estero Real is situated in the southeast of the Gulf of Fonseca, a large bay on the Pacific coast of northern Central America shared by Nicaragua, Honduras and El Salvador. The WHSRN designation led to increased interest in the site, triggering the first tri-national shorebird count in the Gulf of Fonseca in January 2017. The survey was designed to collect baseline data on the numbers of shorebirds using the area as a wintering site, as well as to count the year-round resident shorebird species. Due to the success of the tri-national survey, a second survey was carried out in May 2018, intentionally later in the season to capture data on longer-distance migrants – those stopping at the Gulf of Fonseca during their northbound migration.

During the first tri-national survey, in January 2017, a total of 40,078 shorebirds representing 26 species was counted at a total of 72 sites within the Gulf of Fonseca. As could be expected, one of the more common species sighted was the Wilson’s Plover, with a total of nearly 3,000 individuals counted (approximately 40% of the beldingi subpopulation!) in the whole survey area. Other species with significant totals included the Semipalmated Plover Charadrius semipalmatus (4.027 individuals, 2% of its global population), Whimbrel Numenius phaeopus (1.156 individuals, nearly 3% of biogeographic population of subspecies rufiventris) and “Western” Willet Tringa semipalmata inornatus (5.218 individuals, just over 3% of its biogeographic population).