The 115th Christmas Bird Count in the West Indies/Bermuda

There were 20 Christmas Bird Counts in the region this season; Bermuda, four from the Bahamas, two at the Dominican Republic, four from Cuba,  one from Haiti, three from Puerto Rico, three from the US Virgin Islands and two from the British Virgin Islands. The hope is that Jamaica will return with one or more counts.

High species count honors go to Cabo Rojo, Puerto Rico with 125, six more than last year, followed by Arecibo, Puerto Rico with 124.  Highest participant total goes to Fajardo, PR at 57 followed by Arecibo with 42 people counting birds.  Salinas-Bani, Dominican Republic had the greatest number of birds counted per party/hour with 3.92 (47 species and three birders in four hours), compared to Cabo Rojo’s 125 species by 30 birders in 41.7 hours (0.10).

Bermuda mustered 30 participants counting for a total of 60 party-hours yielding 90 species, nine fewer than last year. Birds per effort last year was .077, while this year it was .05.  Given the organization and consistently high effort of the Bermudan cohort, these numbers suggest fewer birds migrating or at least being found at this isolated port of call. Two years ago, 101 species were reported with 16 participants and 59.5 hours of counting. The effort yielded .106 birds (see Table 1.).  Assuming consistent participation, perhaps only two reasons can attest to the decline: fewer birds or changing weather conditions for migrants, or both.

Table 1. Bermuda CBC birds per unit effort determined by total birds/# hours/#participants.

*this number increased average number of participants by 17%

Looking to the future, Cuba after two seasons could be a contender for most endemics (island total 25) seen during a CBC. Eighteen endemics seen on the Bermejas count represented 45% of all birds reported (40) from the circle and 72% all endemics.  With several more years of monitoring, Puerto Rico (17 endemics) had 15 endemics or 88% noted from three of the island’s counts.   The Puerto Escondido, DR count which is the most productive in terms of endemics counted offered 25 endemics, or 89% of Hispaniola’s 28 endemics, which accounted for 34% of the 75 species reported.

Native ducks and waterfowl- Just two counts provided a total of 50 West Indian Whistling-Ducks while 594 White-cheeked Pintails were counted in 13 circles. Ruddy Ducks (114) were found on seven counts, nearly a third of all circles. This species has increased in the region in recent years. Least Grebes (124) also increasing in the region were found on 10 of the 20 counts submitted this year. Four species of migrant shorebirds are well represented in this somewhat arbitrary abundance level. Three plovers and a sandpiper are regular winter residents. Many other sandpiper species may be counted during the CBC period, but do not reach the >65% threshold among the 20 circles. Indeed, some circles have ample habitat for shorebirds while others do not.

Landbirds and introduced species-The most commonly reported land bird was Northern Mockingbird seen on 18/20 counts followed by Common Ground-Dove (Table 2).  Neotropical landbird migrants were led by Northern Parula, Northern Waterthrush, and American Redstart with relative abundance among the 20 circles at or above 80%.  Eight warbler species with more than 65% abundance in regional counts accounted for the majority of neotropical migrants, about one-third of all possible species to be recorded. Bermuda consistently records the greatest number of warbler species. Given its location at 73 degrees west longitude, the same as St. Croix, observers at Puerto Rico/Virgin Islands could expect to find a larger suite of species provided migration conditions are not severe.

The highest percentage (relative abundance) for an introduced species was 65% (13/20) for House Sparrow outpacing Eurasian Collared-Dove at 25%. This urban dove appears to be holding on, yet not dramatically depressing numbers of native ground-foraging columbids which can occupy forest openings.

Table 2. Relative abundance (occurrence > 65%) of migratory (17) and non-migratory species (17) reported among the 20 West Indian CBCs.

* indicates some continental, migratory individuals present when relative abundance is high.