Date: 1/12/18 10:34 am From: Nathaniel Wander <nw105...> Subject: [obol] Brown Creeper (Certhia americana) phylogeny
While I’m guessing that Bob O’Brien offered the remark thatBrown Creepers were the “aboutthe closest thing that you can get to a woodpecker” in an act of kindness tolighten the mood and “spare the blushes” of an honest mis-identification, theyare, of course, nothing of the sort. Creepers (treecreepers in the Old World) are songbirds: they don’t looklike woodpeckers, they don’t behave like woodpeckers and they have no nearphylogenetic relationship to woodpeckers. Their one interesting connection to woodpeckers is that they compete withand defend territories against Redheaded Woodpeckers (Melanerpes erythrocephalus) in eastern North America. Even still, they prefer arachnids to insectsand eat seeds in winter.
Brown Creepers’closest relatives are the as many as ten treecreeper species in Europe andAsia. After that, they appear to be mostclosely related to gnatcatchers and are considered general kin to wrens—these speciescomprise the family Certhioidea. Thereare thought to be about six to nine races of Brown Creepers in North America,not counting a few Mexican races that reach the mountains of Arizona and NewMexico. The details of their relationshipshave been much debated. In the past theNorth American birds have sometimes been divided into three or four discretespecies, sometimes even lumped with the Eurasian Treecreeper (C familiaris). There was a proposal before the AOS lastspring to divide the present single New World species into a North Americanspecies (exclusive of the highland Arizona/New Mexico populations) and aMexican/Central American species (including highland Arizona/New Mexico populations)possibly to be named Nearctic Creeper and Neotropical Creeper respectively. I can’t see that it has been voted on yet.
Otherwise, creepers feed on tree trunks by pokingbeneath bark flakes rather than boring holes like woodpeckers. They are not cavity nesters, butweavers. They communicate via highpitched calls and songs, not drumming and they are cryptically colored ratherthan boldly marked. They take insectsbut prefer arachnids and, of course, their prey range is generally significantlysmaller than that of woodpeckers: I’ve found no evidence that they consume ants.
It may be that Bob wasn’t genially joking, but was thinking ofwoodcreepers (Dendrocolaptinae) rather than creepers/treecreepers. These 50-60 odd Central/S American forestbirds fall in the woodpecker size range and have some evolutionarily convergentfeatures with the latter including stiff tails which they use woodpecker-like asan important point of contact in shimmying up tree trunks. Woodcreepers generally have heavy bills, butuse them for bark-probing like creepers/treecreepers rather than boring likewoodpeckers. Their generally crypticcoloration is also sometimes said to be convergent with creepers/treecreepers. Woodcreepers too are passerines, thoughsuboscines (like flycatchers) rather than ‘true’ oscine songbirds. Suboscine songs are generally less complexthan those of oscine songbirds and typically are acquired genetically ratherthan learned.
Nathaniel WanderPortland, OR
Max Planck is supposed to have said: A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.Andreas Wagner observed of Planck's remark: Science, like nature, advances one funeral at a time. (Arrival of the Fittest, p.197)