The handy thing about the songbird’s fall migration is that sometimes the birds come to you. You're not likely to find southbound shorebirds or geese in the typical Berkeley back yard. But we do get a steady trickle of warblers
The handy thing about the songbird’s fall migration is that sometimes the birds come to you. You're not likely to find southbound shorebirds or geese in the typical Berkeley back yard. But we do get a steady trickle of warblers, vireos and flycatchers in late summer and early fall, and now and then a surprise. Last weekend I had a brief look at a female western tanager in the island mallow near the garage: a midsized yellow-green songbird with two yellow wingbars and a large pale bill; as far as I can recall, she was a new addition to the yard list.
Western tanagers have always seemed like one of those quintessential Sierra birds. But they're not confined to the high mountains; the Contra Costa breeding bird atlasers has found them nesting in the Berkeley Hills, as well as the Diablo Range. Most likely the tanager in the yard came from the northern part of the species' range, which stretches as far as the Chilkat and Skagway rivers in Alaska.
Males are unmistakable, with their blazing red heads. That color, it turns out, comes from an unusual pigment called rhodoxanthin, which seems to be sequestered from insects they eat. I have to wonder if males and females have different dietary preferences; not sure anyone has investigated that. The other North American tanagers—summer, scarlet, and hepatic—get their reds from a more common type of carotenoid pigment, as do male house finches.
The female in my yard was about on schedule for her species. A few precursors reach Southern California as early as mid-July, but the peak of the California migration spans late August through late September. Stragglers have been seen as late as November. At least in southern British Columbia, adults head south first. They fly by night, most traveling singly or in pairs but sometimes in groups of up to 30. They're suspected of being high fliers, since their nocturnal flight calls have never been documented.
Some western tanagers only travel as far as the coastal region from Santa Barbara to San Diego, where about 75 are documented each year in the Audubon Christmas Bird Counts. They're attracted to flowering eucalyptus trees, feeding on nectar and insects. (Eucs can be dangerous