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.

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.

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

Bold= Introduced

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

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.