Punta Sal, Honduras
Another day, another country, another great tropical experience. Birds and plants dominated our final day on the Sea Lion. We left the beauty of Belize shortly after midnight and cruised eastward in a rolling Caribbean Sea to the north coast of Honduras. Sunrise found us at anchor close to a green and humid rainforest, a feature that is so typical of the Central American tropics. Stately cohune palms lined the steep, bedrock cliffs. The layering of millions of years of volcanic eruptions and pyroclastic explosions was evident. Like the palms, tall gumbo limbo (Bursera sp), autograph (Clusia sp) and erythrina trees, were watching over an entanglement of lush shrubs, vines and epiphytes. Red-mantled howler monkeys could be heard as we rode our Zodiacs slowly and quietly into an impressive, silt-laden river. It drains the higher slopes of western Honduras. Morning life had begun here. Small dugout canoes – the primary means of transportation and food-gathering for the local Garifuna and Landino people – edged along the shoreline or drifted silently, the occupants tugging on hand lines, hopeful of catching a fish or two. This was a peaceful setting, bordered by marginal farmland, stately flowering trees and lush riparian vegetation.
Interrelationships within nature are often amazing. During our river cruise, many species of birds were seen, among them Montezuma’s oropendola, a large, garish and fascinating member of the blackbird family (Icteridae). Most of the world’s 13 species of oropendolas are colonial nesters. Some, like Montezuma’s oropendola, construct intricate, sac-like nests that hang pendulously for four feet or more. We had close looks at a nest tree later in the day – the beach-front coconut palm pictured here. Nest building and courtship were literally in full swing. Adult oropendolas often select a tree in a spacious, open area, as well as one that is adjacent to the nest of a wasp or biting bee species. And for good reasons: first, it seems that the monkeys of the Americas (which will prey on birds’ nests) are loath to leave their arboreal security to run to an isolated tree, even if it is full of nests. Thus, tree selection by the oropendolas can reduce the impact of one group of predators. Yet a greater source of nestling mortality, though, is the botfly. Adult botflies enter the nests to deposit eggs on the helpless nestlings. As the eggs hatch, the larvae burrow in for an extended meal, often leading to the demise of the young birds. Reducing the chance of this happening are the nearby bees or wasps. They, too, can be victims of botflies, but can detect their approach and will attack. Thus, a second source of protection is afforded to the oropendolas. But, now, add to this web of nature the Giant Cowbird, a nest parasite, the female of which will lay her eggs in the nests of other bird species, including those of oropendolas. Even though nest parasitism is rarely beneficial to the host, it appears that it can be to oropendolas. If times are good and the supply of fruit, nectar and spiders is abundant for the host birds, one or two cowbird nestlings among in the brood may actually be beneficial. It seems that young cowbirds have a habit of grooming their nest-mates, often ridding them of botfly eggs and larvae. With all of this help, one would expect oropendolas to do well as breeders. But the opposite is true; the average fledging of young is only a single bird for every two nests. Those that make it, however, live on. A number of banded females were found to be still breeding in their 26th year. Nature never ceases to surprise.
Another day, another country, another great tropical experience. Birds and plants dominated our final day on the Sea Lion. We left the beauty of Belize shortly after midnight and cruised eastward in a rolling Caribbean Sea to the north coast of Honduras. Sunrise found us at anchor close to a green and humid rainforest, a feature that is so typical of the Central American tropics. Stately cohune palms lined the steep, bedrock cliffs. The layering of millions of years of volcanic eruptions and pyroclastic explosions was evident. Like the palms, tall gumbo limbo (Bursera sp), autograph (Clusia sp) and erythrina trees, were watching over an entanglement of lush shrubs, vines and epiphytes. Red-mantled howler monkeys could be heard as we rode our Zodiacs slowly and quietly into an impressive, silt-laden river. It drains the higher slopes of western Honduras. Morning life had begun here. Small dugout canoes – the primary means of transportation and food-gathering for the local Garifuna and Landino people – edged along the shoreline or drifted silently, the occupants tugging on hand lines, hopeful of catching a fish or two. This was a peaceful setting, bordered by marginal farmland, stately flowering trees and lush riparian vegetation.
Interrelationships within nature are often amazing. During our river cruise, many species of birds were seen, among them Montezuma’s oropendola, a large, garish and fascinating member of the blackbird family (Icteridae). Most of the world’s 13 species of oropendolas are colonial nesters. Some, like Montezuma’s oropendola, construct intricate, sac-like nests that hang pendulously for four feet or more. We had close looks at a nest tree later in the day – the beach-front coconut palm pictured here. Nest building and courtship were literally in full swing. Adult oropendolas often select a tree in a spacious, open area, as well as one that is adjacent to the nest of a wasp or biting bee species. And for good reasons: first, it seems that the monkeys of the Americas (which will prey on birds’ nests) are loath to leave their arboreal security to run to an isolated tree, even if it is full of nests. Thus, tree selection by the oropendolas can reduce the impact of one group of predators. Yet a greater source of nestling mortality, though, is the botfly. Adult botflies enter the nests to deposit eggs on the helpless nestlings. As the eggs hatch, the larvae burrow in for an extended meal, often leading to the demise of the young birds. Reducing the chance of this happening are the nearby bees or wasps. They, too, can be victims of botflies, but can detect their approach and will attack. Thus, a second source of protection is afforded to the oropendolas. But, now, add to this web of nature the Giant Cowbird, a nest parasite, the female of which will lay her eggs in the nests of other bird species, including those of oropendolas. Even though nest parasitism is rarely beneficial to the host, it appears that it can be to oropendolas. If times are good and the supply of fruit, nectar and spiders is abundant for the host birds, one or two cowbird nestlings among in the brood may actually be beneficial. It seems that young cowbirds have a habit of grooming their nest-mates, often ridding them of botfly eggs and larvae. With all of this help, one would expect oropendolas to do well as breeders. But the opposite is true; the average fledging of young is only a single bird for every two nests. Those that make it, however, live on. A number of banded females were found to be still breeding in their 26th year. Nature never ceases to surprise.
