The Yellow-rumped Warbler
By Gord Gadsden
May 5, 2008
Yellow-rumped Warblers are without doubt one of the most adaptive and versatile of the warbler species found in B.C. They are the most likely warbler to be seen on a cool December day when most other warbler species are enjoying the warm tropics. They can be found flitting around at the top of a 40' cottonwood tree or prowling around on the ground in the middle of an open field. Their feeding style can mimic flycatchers, nuthatches and sparrows depending on the habitat they are currently using or the food source available.
Yellow-rumped Warblers are very abundant and can be found year round in the Lower Mainland. Their numbers are most abundant from April to May and then again during the fall migration from late August to the end of September. A few will breed in our area every summer. Most will migrate south for the winter but often a few will stick out the winter up here. Their adaptive behaviour accounts for much of their success. They are adept at 'flycatching' flying insects and are often seeing flying from a branch to pick off an insect out of mid-air or even off the surface of water. They can cling on tree trunks to glean insects from the bark and seem content to join the sparrows on the ground looking for food. Insects are their main food source but will also eat berries when necessary; an important fallback for cold days when insects are hard to come by.
There are two sub-species of Yellow-rumped Warbler, while hybrids are documented, these two sub-species are visibly different and, with a little practice, can even be distinguished apart by their song and calls. The Audubon's race is the most common sub-species in the West. They are darker and have a yellow throat. The 'Myrtle' sub-species is widespread but is more common in the East. They are not as dark on the breast, have a white throat and a more patterned face.
Yellow-rumped Warblers are both easy and fun to watch. They are quite noisy frequently making a "chep!" call note as they feed. They are often seen down low in the trees on prominent perches which is a nice break for one's 'warbler neck' sustained from too much of watching their cousins in their preferred habitat far above the ground.
Links and sources:
Ehrlich, Dobkin and Wheye, (1988)
Sibley, D. (2000)