The 118th CBC in West Indies

This season’s 24 counts provided some valuable insight into the effects of hurricanes Maria (Cat 4) followed quickly by category 5+ Irma (Figure 1.) on CBC results for Puerto Rico and the US/British Virgin Islands (see image of Virgin Islands before and after hurricane Irma). The storm was at peak strength by 6 September with Irma posting top sustained winds of 185 miles per hour and 225-mile-per-hour gusts. Hurricane Maria crossed the Virgin Islands 16 September from a more southerly path affecting St. Croix and Vieques, PR. In spite of the hurricane Puerto Rican observers surveyed four traditional areas. These results strengthen an already intriguing transect of the Puerto Rico Platform from Cabo Rojo, PR in the west to Anegada, BVI to the east. 

Figure 1. Forecast rack of hurricane Irma, 11 September 2017.

Photo: Robert L. Norton

 

Figure 2. Before (upper panel) and after (lower panel) images of northern U.S. Virgin Islands (St. Thomas and St John) to British Virgin Islands (Tortola and Virgin Gorda) showing striking image of 100 plus square miles of near complete defoliation.

Photo: Robert L. Norton

There are now seven CBC circles reporting from The Bahamas and from Puerto Rico. The Virgin Islands usually has four counts, but Anegada was not represented this year because of logistics. In the Greater Antilles, Cuba is holding steady with four counts, Dominican Republic with two and Les Cayes, Haiti, the birthplace of J. J. Audubon, with one. Bermuda remains one of the stalwart counts strategically located near the Atlantic Ocean’s Gulf Stream.

A review of the species with the highest numbers (greater than 1000) post hurricane season throughout the region reveals an interesting perspective. Salinas, Cuba is an important refuge in the region not just for American Flamingos, but many other waterfowl including migrants. Highly urbanized areas such as Bermuda, New Providence, Bahamas and San Juan, PR tend to have the lion’s share of introduced species. On the plus side, the Bananaquit, a frugivore, faired very well post hurricanes Irma and Maria as did Gray Kingbird, an insectivore, and Greater Antillean Grackle, an omnivore. The greatest concern following devastating hurricanes is for endemics, especially hummingbirds.

 Table 1. Ranking of species tallied in highest numbers from 23 CBC 2017-18

Species

Regional Total

Highest Circle Count

American Flamingo

1966

Salinas, Cuba (1922)

Rock Pigeon

1855

Bermuda (598), San Juan (518)

Blue-winged Teal

1793

Salinas, Cuba (1333)

Eurasian Collared-Dove

1649

New Providence, Bahamas (1398)

Cattle Egret

1427

Les Cayes, Haiti (638)

House Sparrow

1373

Bermuda (1099)

Mourning Dove

1335

Bermuda (1032)

European Starling

1326

Bermuda (1199)

Gray Kingbird

1239

Puerto Rico (824)

Greater Antillean Grackle

1223

Puerto Rico (1137)

American Coot

1044

New Providence (529)

Bananaquit

1030

Puerto Rico (760)

Laughing Gull

1000

New Providence (702)

Bold= Introduced

 

Table 2. Numbers of Trochilids of Greater Antilles post hurricanes, 2017.

Species

Total numbers

Circles

Antillean Mango

37

Puerto Rico (19), Dominican Rep. (18)

Green-throated Carib

21

PR (5), USVI (15), BVI (1)

Bahama Woodstar

39

 

Vervain Hummingbird

14

Hispaniola (14), PR (0)

Bee Hummingbird

1

 

Cuban Emerald

143

 

Hispaniolan Emerald

14

 

Puerto Rican Emerald

9

 

Antillean Crested Humm.

4

USVI (3), PR (1)

Puerto Rico has five species of hummingbirds, highest number of any West Indian location. However, the Vervain Hummingbird was not recorded at Puerto Rico. This may be a result of competition from the larger species that occupy similar habitat. In the Virgin Islands, the two most common species, Green-throated Carib and Antillean Crested Hummingbird showed similar stress and proportions with the larger Carib outnumbering the Crested Hummer. In a normal year, these species are recorded in equal numbers on CBCs.

Again, thanks to the dedicated observers (citizen scientists) who sacrifice time and effort to strengthen our understanding of avian dynamics especially in a changing climate.

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