 Nothing
says "Neotropics" like Toucans. Yes, the New World tropics have impressive
macaws, but there are gaudy parrots elsewhere in the world; yes, there
are glamorous hummingbirds, but hummers are also found in temperate North
America forest; yes, there are other groups endemic to the Neotropics (antbirds,
ovenbirds, tapaculos, gnateaters), but none are universally recognized
by the man (or woman) on the street. Everyone knows — and everyone loves
— toucans. And toucans exist only in the New World tropics.
No doubt this is because of their big and usually colorful bills. Keel-billed Toucan (left in a classic shot by Cagan Sekercioglu) is one of those species, and it ranges widely in the lowlands from south Mexico to northern South America. The huge bill is a very lightweight keratin, and is often used for plucking and swallowing fruit. Most toucans are primarily fruit eaters (Remsen et al. 1993), although though there are exceptions (detailed below). It is easy to recognize a toucan — one argument made for retaining them as a separate family in the face of biochemical data (see below; Short & Horne 2001, 2002) — but there are significant differences in the size of the birds, the size of the bills, and the shape and length of the tails among the six genera. It is the big Ramphastos toucans, like Keel-billed, that mold the public image of this family. Short & Horne (2001) even use the word "Rainbow-billed Toucan" for this taxa. Yet there is much disagreement as to how many species there are. Recent books have listed as few as 34 (Short & Horne 2001, 2002), to 37 species (Dickinson 2003) to 41 (Sibley & Monroe 1990, Clements 1991). Short & Horne (2001, 2002) point to "massive hybridization" between "Cuvier's" R. t. cuvieri and White-throated Toucan R. tucanus, on one hand, and between "Yellow-ridged" R. c. culminatus, "Citron-throated" R. c. citreolaemus, and Channel-billed Toucan R. vitellinus, on another hand, supporting the more conservative approach to speciation in these birds, as proposed some time ago by Haffer (1974). This conservative approach as been adopted by the South American Checklist Committee. And all this before Navarro et al. (2001) proposed splitting Emerald Toucanet into 7 species (more below)! For the moment I adopt the 'middle-of-the-road' species-level taxonomy in Dickinson (2003). |
||||
 Although
Ramphastos
toucans are impressive, I prefer some of the smaller araçaris and
toucanets. One of my absolute favorites is Curl-crested Araçari
(right in a stunning shot by Arthur Grosset). The rich burgundy
and ivory contrasts are gorgeous, the long tail unexpected, and the little
white "curls" on the crown a real topper. Rita and I lay on our backs in
the middle of the Amazonian rainforest, lying on a tarp provided by Rio
Cristalino Lodge, and staring up at the fruiting tree in the canopy some
100 feet above us. This is where our Curl-cresteds were feeding. Arthur
Grosset took this photo on the grounds of Rio Cristalino Lodge (see below
for links to the Lodge and to his web site).
Dickinson (2003) lists a dozen Pteroglossus araçaris, and I surprisingly discovered that (under that species list) I've seen them all. Among them are a wide array of green, yellow, black and red birds with various breastbands and differing bill patterns. They are not all easy to identify. One of the ironies I find in some world birders is that they are able to say the word "araçari" just fine — with its soft "c" sounds because of the little curlicue attached to the "c" [to wit, "arr-a-sar-ee"] when the same birders butcher the soft "c" (with the same curlicue) in jaçana, excitedly calling out "jah-KA-na." Oh well, who was it that said "consistency is the hobgoblin of small minds"? |
||||
 The
toucan on the Fruit Loops box, and at Disneyland, is patterned after the
species with the memorable title of Toco Toucan (left). In the Brazilian
Pantanal one can spot the Toco sitting in the canopy of a lone tree from
some distance away. It is the only species of toucan adapted to non-forested
habitats. It is also a toucan that indulges in much more than fruit. We
watched it grab a baby from an oropendula nest and fly off to consume it.
Remsen et al. (1993) found that the stomach contents of this species was
quite variable, with 44% "fruit-only" and another 44% with mixed arthropods
and fruit.
Recent molecular evidence has proven that New World barbets, toucans, and the two birds in Semnornis (e.g., the toucan-barbets) are more closely related to each other than they are to Old World barbets (Burton 1984, Prum 1988, Sibley and Ahlquist 1990, Lanyon & Hall 1994, Barker & Lanyon 2000, Johansson et al. 2001, Johansson & Ericson 2003, Moyle 2004). Given the evidence that toucans are actually 'big-billed New World barbets' when compared to barbets in the Old World, there are several different taxonomic approaches. One approach is to lump all of them into one huge Barbet family, leaving the Toucans as a subfamily (Dickinson 2003). The opposite approach is taken by the Handbook of the Birds of the World (Short & Horne 2002) sticks with the traditional approach of two families: all the barbets (including the toucan-barbets) in a barbet family and the toucans in a toucan family. They argue that it is easy to tell whether any bird in the group is a barbet or a toucan, and that the barbets are ecological counterparts on each of the three major tropical continents. This is true enough, but it is a bit like sticking your head in the ground to avoid the new evidence of relationships. There is now no serious doubt that toucans arose from the lineage of New World barbets well after that lineage had splintered into three directions. I prefer a more modern approach, now adopted by the South American Checklist Committee. They treat the two groups of Old Word barbets as two separate families, Asian Barbets [Megalaimidae] and African Barbets [Lybiidae], and then separate the three New World groups into separate families as well: New World Barbets [Capitonidae], Toucan-Barbets [Semnornithidae] and Toucans [Ramphastidae]. This treats all the groups on the same level. You can reach my pages on each of these families as follows:
|
||||
Ridgely & Greenfield (2001) thought it might be an "oversimplification"
to treat Emerald Toucanet (below; photo by Marc Fenner) as
just one species. The subspecies
lautus,
albivitta,
cyanolaemus,
dimidiatus,
and atrogularis, as well as Middle American wagleri and caeruleogularis,
were formerly each considered separate species but Haffer (1974) treated
them all as conspecific, and Short & Horne (2001) pointed out that
the allopatric taxa are no more distinctive than those known to intergrade.
 It seems obvious to me that caution is warranted and that it will require additional studies, and (preferably) a molecular analysis to determine which (if any) of the populations are sufficiently evolved to be likely reproductively isolated under the Biological Species Concept. It was thus disappointing, but not surprising, to see that Clements' on-line "updates" accepted this seven-way split. Although this caused some glee among groups of tickers, the proposal has not gained wide acceptance. The South American Checklist Committee has not followed endorsed the split among South American populations. Clearly, there is much yet to learn about toucan taxonomy (among other topics) but, for now, it is enough to appreciate their variety and beauty. |
||||
|
Photos: Cagan Sekercioglu photographed the Keel-billed Toucan Ramphastos sulfuratus in Rincon de la Vieja NP in northern Costa Rica in August 2000. Arthur Grosset photographed the Curl-crested Araçari Pteroglossus beauharnaesii at a fruiting tree at Rio Cristalino Lodge, Brazil, in 2003. The Toco Toucan Ramphastos toco was in the Brazilian Pantanal in Aug 1999. Marc Fenner photographed the Emerald Toucanet Aulacorhynchus prasinus at Monteverde in Costa Rica in April 1990. Photos © Cagan Sekercioglu, Arthur Grosset, Don Roberson, and Marc Fenner, as credited, used with permission, all rights reserved. Many more outstanding Arthur Grosset photos are on his web page; he particularly features South America. Photos from around the globe highlight Cagan Sekercioglu's web site [Cagan is a grad student at Stanford]. Marc Fenner hosts a fine web site on birding Costa Rica. Use this link to Rio Cristalino Lodge for information on this fabulous place. Family Book: Rating: I must confess that I don't actually own this book, nor have I done more that quickly glance through it in a bookstore. But every one of the Oxford Univ. Press series on bird families has been excellent, and this looks equally solid. I presume that the "meat" of this book has been summarized by the same authors in their Handbook of the Birds of the World series (Short & Horne 2002) which I do own and have studied.Literature cited: American Ornithologists' Union. 1998. Check-List of North American Birds. 7th ed. A.O.U., Washington, D.C. |
