With a name that includes a bright colour like 'orange' and an ornamental description like 'crown', one might be under the impression that orange-crowned warblers are dazzling little creatures. That impression would be wrong. In fact, the orange crown is barely perceptible unless you see a male puffing up his crown in an aggressive display or you blow on his crown feathers while you hold him in your hand. Some have even gone so far as to label this little songbird the drabbest of all the warblers in North America.Despite its lack of showy plumage, the orange-crowned warbler is a fascinating bird to study. It is one of the most widely distributed warblers in North America, able to inhabit conditions as diverse as the arid, Mediterranean climate of southern California and the sub-arctic, highly seasonal environment of Alaska and northern Canada. It also exhibits diverse migratory strategies. For instance, the subspecies we study in the southern portion of its breeding range is a year-round resident of southern California, while the northern subspecies migrates all the way to the Gulf coast to over-winter. Such differences in breeding locale and migratory strategy translate into marked differences in life history, as southern breeders have low fecundity and high survival while northern breeders have high fecundity and low survival. We ecologists classify these populations as falling at the 'slow' and 'fast' end of the life-history continuum, respectively, classifications that carry with them a whole suite of additional traits. Our primary research aim is to identify the causes and consequences of life-history diversification among populations of orange-crowned warblers.
So how do we do this? Well, 'unfortunately' this requires that nearly half our year be spent in the wilds of California and Alaska, a price we are willing to pay in the name of research. With our trusty field assistants in tow, we record the locations of territorial individuals, capture and band them for individual identification, and follow their breeding activities over the course of the season. We find nests, videotape them to observe parental activity, and when the nestlings are old enough we take them out for a brief period of time to band and measure them. The populations we study have non-overlapping breeding seasons, so we are able to spend February, March, and April in California and May, June, and July in Alaska. Stay tuned as our fieldwork gets underway and we to peer into the lives of these cryptic warblers.
