Bird Watching: In Search of Endemic Species on a Trip to Puerto Rico
This column is the second of two chronicling a four-day birding trip my wife and I took to Puerto Rico in May.
I take this opportunity to discuss some of the general characteristics of island birds. In the last column, we saw that island species diversity is generally lower in mainland source populations. We have also seen that exotic species have an easier time establishing themselves on islands, especially in disturbed areas.
Today’s column will focus on organisms that are restricted to one or a few islands. These species are qualified as endemic by biogeographers.
It is easy to see how endemic species can appear. A few individuals of a mainland species arrive on an island and over time diverge from the mainland species. Sometimes these endemic species are found only on the island where they appeared. In other cases, endemic species may disperse to neighboring islands.
For example, the great grackle is found on the four islands of the Greater Antilles but nowhere else. Similarly, the Lesser Antillean Bullfinch is found over most of the Lesser Antilles.
Island endemics are restricted to a single island. Puerto Rico has 17 endemic species and these were the main targets of our trip.
Most Puerto Rican endemic birds are widespread and common. We had some time for bird watching in the afternoon we arrived. At Bosque Estatal de Cambalache, our first endemic species was a Puerto Rican cuckoo lizard, with a lizard in its beak! We found Puerto Rican bullfinches and Puerto Rican spindalis (a relative of the tanager).
By moving to a suburb of Barcelonata, we hit the jackpot. We saw the Puerto Rican Flycatcher, Green Mango (a hummingbird), Puerto Rican Oriole, Adelaide Warbler and Puerto Rican Woodpecker.
After a hearty dinner, we stopped at a small stretch of forest in Manati where our guide Julio Salgado had staked a Puerto Rican owl. He responded quickly to a check-in and we got some great looks via a headlamp.
It was a great start to our trip. A total of three hours of birding produced nine of the 17 island endemics.
We started birding early the next day at Bosque Estatal de Rio Abajo. The region soon produced three other endemic species: the Puerto Rican vireo, the Puerto Rican emerald (a hummingbird), and the Puerto Rican tody. Todies are charming birds. Green on top with a red throat and a long, slender beak, these fiery birds are not much larger than a hummingbird and fly with the same speed and abandon.
But the main reason to visit this site was to find the Puerto Rican parrot. Only about 100 of these birds exist in the wild with another 450 held in a captive breeding program. A flock of eight parrots landed near us and I was able to take some great pictures. None of the birds pictured had bands, indicating that they were born in the wild. Good news!
With 13 endemics in the bag, we headed to the southwestern part of the island. A stop at a mountain site produced two endemic targets. The Elfin Woods warbler looks like a particularly dark black and white warbler. Puerto Rican birds were not recognized as a separate species until 1972.
We also saw my most desired species, the Puerto Rican Tanager. Although it has dull plumage and a weak song, I find it fascinating because it has come a long way from its continental ancestor. DNA evidence helps classify this bird into its own family, a single-species family.
We obtained our last two endemic species in the town of Lajas. The red-winged blackbird is an endangered species with only about 1000 extant individuals. Brood parasitism by shiny cowbirds is a major threat. We saw about 50 blackbirds in a mangrove thicket.
After dark, we visited the same mangroves and found a Puerto Rican nightjar to wipe the slate clean of all Puerto Rican endemics.
A full list of the species we saw and photos of many of them can be found at ebird.org/tripreport/57209
Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes comments and questions from readers to [email protected]