A CONVERGENCE OF CONVERGENCES

When I was a boy, my father regaled me with stories of the spectacular “toucans” he remembered from his native Indonesia. As I grew older I questioned these tales when I learned that toucans are restricted to tropical America. Eventually, I decided he was talking about hornbills, the Asian birds that resemble toucans but are unrelated.
One doesn't have to look too far to find examples like these of convergent evolution, and it's often amazing how closely two unrelated species can come to resemble each other after exploiting the same niche. Toucans, which are related to woodpeckers, are found in wooded areas throughout the New World tropics. Their diet consists chiefly of fruits, but is supplemented with small animals; the diet varies some from species to species. In the Old World tropics, the same can be said for hornbills, whose closest relatives are the hoopoes. The most typical members of the two groups are the toucan genus Rhamphastos (which includes the most widespread species, the Keel-billed Toucan [R. sulphuratus]) and the hornbill genera Buceros and Aceros (best known of which is the Great Pied Hornbill [B. bicornis], found throughout Southeast Asia, and one of the species that my father probably knew as a boy). Birds of these three genera are noisy, black forest birds that tend toward pale breasts. Their short legs end in enormous feet. They are the most frugivorous of their respective families, and are armed with enormous, brightly colored bills that serve both as tools and social signals. Rhamphastos, Buceros and Aceros all nest in tree cavities and exhibit a high degree of intelligence. Aside from their much larger size, the hornbills' long white tails provide the main difference in outward appearance, diverging from the stumpy black toucan tails.
It was only a decade or so ago that I leaned about another convergent feature of the two groups—one that also restored my father's credibility. The word “toucan” comes from the Tupi Indian name for the bird, “tucan.” Oddly enough, the Malay word for hornbill is precisely the same: “tucan.” It's tempting to look for a lexicological link here—Dutch sailors carrying the term from Suriname to Indonesia, or some other contrivance. Hornbills and toucans are such magnificent and conspicuous birds though, that I can't imagine either culture adopting a new name for them from foreign explorers. No, I can find no logic in this linguistic anomaly, just another mysterious coincidence that keeps me marveling confusedly at the world.
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upper: DRUNKEN HORNBILL--RED-KNOBBED HORNBILL (1996) watercolor 9" x 12"
center: INSTANT OF OPPORTUNITY--EMERALD TOUCANETS (1995) acrylic 22" x 30"
lower: GREAT PIED HORNBILL (2001) acrylic 30" x 20"