Chiapan Mystery Bird

 
Feeding Azure-rumped Tanager in Chiapas, Mexico.

Story and Photos by Lou Jost

       In these days of intimate bird films and videos, detailed guides and
bird magazines, something has been lost from birding North America.
During the eighteenth century, Audubon or Wilson wondered about the plumage colors of rare birds and could be surprised by a new specimen, but today the mystery is gone. Want to know the color of the breast band of a Bachman’s Warbler? Just look it up in your favorite field guide. How many stripes does a Short-tailed Hawk have on its tail? Turn back a few pages. Does a Keel- billed Toucan have a red spot on its bill? Look at the plate in a field guide to Mexican birds.
      Impressive, this knowledge, but at the same time a bit stifling. A birder wants surprises, but there are none left at this level.
      Or almost none. One and only one bird north of Panama has managed to elude the grasp of the field guides. It is one of the least known of American birds, the Azure-rumped Tanager (Tangara cabanisi). Roger Tory Peterson's Field Guide to the Birds of Mexico says, "Extremely rare; only two specimens known," and he does not paint it. Irby Davis' Birds of Mexico and Central America does attempt to paint the bird, showing an unmarked turquoise breast, bright green unmarked cheeks, and a plain blue-green back. But when we turn to another field guide, Miguel Alvarez del Toro's Las Aves de Chiapas, we find a completely different illustration, a dull, uniformly blue-gray bird, heavily spotted with black, and no trace of green anywhere. A third guide, Ernest Edward's Field Guide to the Birds of Mexico, shows a bird completely different from either Davis' or Alvarez del Toro's.

     Why such divergence? The answer lies in the extreme rarity of the bird and the lack of good adult specimens. The Azure-rump was first described in 1868 from a single immature specimen shot in a remote part of Guatemala (where the bird was never seen again, according to Hugh C. Land's Birds of Guatemala). Seventy years later, a second example was found, this time in Mexico in the Chiapas Mountains. It too was an immature bird. Over the next few decades only two additional documented sightings were made, and the breeding range and habits of this species remained a mystery. No wonder the field guides couldn't capture it.

The azure-blue rump gives the bird its name.

      We might still be in the dark about the Azure-rumped Tanager today, if not for the Mexican naturalist Miguel Alvarez del Toro. In 1960, Alvarez del Toro led the first scientific expedition to a remote Chiapan mountain named EI Triunfo. He was searching for the nearly extinct Horned Guan, and in Triunfo's cloud forest he finally found it. He found many other rare and endemic animals there, including some of Mexico's last Resplendent Quetzals. He had stumbled upon a naturalist's paradise, an island of virgin cloud forest surrounded by sharp belts of pine, subtropical and tropical dry forest. On his way home from Triunfo, as he crossed a canyon in the subtropical belt, Alvarez del Toro found one more rarity- an Azure-rumped Tanager sitting in a tree.
      Word of his discoveries spread, but the inaccessibility of the area made it difficult to explore further. Nevertheless it soon became clear that one particular canyon, in fact one particular fig tree (Ficus sp.) in that canyon, regularly entertained Azure-rumped Tanagers. Finally in 1982, Bret Whitney, a professional birding guide, saw a Tanager carrying nesting material into that huge fig tree. It was the first Azure- rumped Tanager nest ever found, confirming that the canyon was indeed part of the bird's breeding grounds. The mystery had been solved.
      When Whitney told me he had found the Tanager breeding ground in El Triunfo, I remembered all those enigmatic field guide entries and contradictory paintings, and I saw a chance to resolve the conflicts. I went to live on the slopes of El Triunfo from January to May 1986, hoping to take the first close-up photographs of the Tanager.

      I set up camp beneath the "Tanager tree," miles from the nearest human. The tanager canyon proved to be a highway for small animals that nightly seemed to enjoy playing with a camper's nerves. Many nights during my stay I rushed out of my tent expecting to face a jaguar, only to find a startled rat or coatimundi in my flashlight beam, staring at me in astonishment. Eventually I learned to let the noises of the night. pass unanswered, and I am glad I didn't read until later Alvarez del Toro's account of his first Triunfo expedition. Not far from where I slept, he had found the freshly blood-spattered clothing and possessions of two men, with jaguar tracks all around.
      No such mishap befell me, and each morning my worries faded into insignificance as whole flocks of Azure-rumped Tanagers entered the canyon-- sometimes thirty at once! Their activity centered on the fig tree above my tent; the Tanagers even christened it with their droppings. To get the best photos I thought I would have to join them up in that tree, so I rigged the tree with climbing rope (using a bow and arrow to shoot a line over the highest branches). But the rope proved unnecessary as large flocks of Tanagers began landing in a nearby berry bush, at eye-level in a sunny clearing. It was a photographer's dream come true. The birds never had close contact with humans before, so they had no fear and soon allowed me to work just ten feet away without a blind as they fed.

     After four or five days the Tanagers had nearly stripped the shrub of berries. I found a second bush of the same species, cut some fruiting branches from it, and carried them back to the first bush. As I walked with the fruiting branches in my hand, the Tanagers began watching me and moved into the trees close by. I quietly sat down with the berry clusters, and the birds landed in the grass around me, hungry, expectant, curious, just five feet away. Their trust touched me deeply. I wished I could have this kind of relationship with more animals-- but most species know humans too well by now.
      The Azure-rumped Tanager discovery came none too soon. Because of Alvarez del Toro's discovery of the Tanager, the Guan and the Quetzal on Triunfo, and because of his energy and influence, the place is now officially protected as a biological reserve (managed jointly by the Mexican government and Alvarez del Toro's Institute for Natural History). Triunfo's birds are generating international interest (especially from World Wildlife Fund-Canada) and tourism (Victor Emanuel Nature Tours and Field Guides, Inc., lead tours into this region), and this may slow or even stop the ongoing destruction of the reserve and its surroundings. I shudder when I recall the convoluted chain of events that led Alvarez del Toro to Triunfo. One break in that chain and the birds could have been left in mystery. The cloud forest would have been replaced. by yet another sterile cow pasture or corn field.
      Yes, the discovery of the Azure- rumped Tanager's breeding ground marked the end of an era for American birding, but it was an era we could no longer afford. Today's world is not safe for mystery birds.

                                                                                        Lou Jost

A version of this article first appeared in the April 1989 Birder's World magazine.

 

  Chiapan Mystery Bird