THE CANYON TOWHEE
by Walter Meagher
photos by Wayne Colony
A bird’s name may not identify the habitat it exclusively inhabits. I see the Canyon Towhee in the matorral (scrubland) so often I think it makes its living there more than anywhere else. Wayne confirms this observation: he sees it most often between La Tienda in El Charco and the Conservatory. If we were radical empiricists we would compose a group of birders divided between watchers of the towhee in the canyon versus watchers of the towhee in the scrubland, counting their numbers in each of these habitats to settle the question of habitat preference. The answer must be that there are more seeds and small insects, to be gathered mostly from the ground or low shrubs in the grassy semi-drylands than in the canyon; therefore more Canyon Towhees in the matorral. We would rename the bird: Scrubland Towhee.
Charles Darwin gave us survival of the fittest as a model for the evolution of species. Aggression, in all life, had a pre-eminent role. More recently, biologists point to the role of non-aggression, not only in mutualism, but in the way some species get along with specific limits to aggression. The Canyon Towhee offers an example of this principle, but to get to the point we need to take a longer than usual journey. Are you ready?
One way to sort birds is by family. If we know what a gull looks like, and how it behaves, we can easily identify a member of the gull family, even without knowing the species name. The Canyon Towhee is dull brown and feeds mostly on or near the ground, as do many sparrows, also dull brown, except for an occasional species with a black dot or a white throat; indeed, towhees and sparrows belong to the same family (Fringillidae). But the Inca Dove is brownish, inconspicuous, feeds on the ground, and belongs to Columbidae, a family of birds that arose much earlier in evolutionary time. Sparrows, towhees, buntings and Inca Doves all have seed-cracking bills. They share this guild: dull-brown, seed-eating ground-feeders.
Ornithologists use ‘guild’ differently from historians. As early as the tenth century, in Northern Europe, guilds were formed to protect merchants. The idea caught on; guilds became proto-unions. All crafts had their guilds; artists did too. Vermeer, for example, had to produce a certain number of works; on their approval by the Guild of Master Painters he was admitted as one of their members. Only then could he sell his paintings to the public. For the ornithologist, guilds are groups of species, not necessarily taxonomically related, that exploit the same set of resources, say seeds, in the same manner - scratching on the ground, for example.
There are many ways organisms partition a habitat, the net effect of which is to decrease inter-specific competition. Guilds foster amity. Instead of nature red in tooth and claw, all the time, we have examples of concord. Not occasional concord, on Sundays only, but concord built-in to the evolutionary scheme. Three cheers for the Canyon Towhee!