Saturday, January 12, 2008
Great Black Hawks
My last year in Tikal, we found two nests of a rather elusive forest raptor, the Great Black Hawk (Buteogallus urubitinga). Since no one had done a systematic survey of their diets, we built a blind (in another tree) near each and did all-day observations of what the adults brought in to feed the young.
These are big hawks (larger than the Red-tailed Hawks common in North America), and they built big nests. But they laid only a single egg (and raised only a single young) at each breeding attempt, and fledged young remained near their parents for extended periods. (A successful nest one year might even preclude nesting the following year by that pair of adults.)
Of all the birds of prey we studied at Tikal, this species had the most diverse diet. Birds, small mammals, toads, bats, lizards, and snakes were brought to feed Junior, but especially lizards and snakes (including Boa constrictors, one of which is pictured below).
One day, I even saw an Eyelash Viper (Bothriecus schlegelli) captured by the male and delivered to the female. She perched on it for a couple of hours before carrying it the rest of the way to the nest and young, so I had some good looks at the snake. It was not unexpected here, but was nonetheless the first documentation of this snake species for Tikal National Park (which takes up a good portion of the northern part of Guatemala). In fact, the journal articles we published on Great Black Hawks have been more frequently cited than any of the others we wrote, and that because a couple of books came out soon after on the reptiles of the Yucatan and of Central America. Those citations had little to do with the birds that held our interest, and everything to do with some of the lizards and snakes upon which they were feeding.
On one day's observation, sitting up in the blind, I killed over 100 tabanos (deer flies) that landed on me.