Fall migration is here. Where do our birds come from?
The May issue of this column introduced National Audubon’s Bird Migration Explorer. It’s a digital platform that shows the migration routes of most North American birds, based on repeated detections of radio-tagged individuals as they travel across the landscape. One can query the platform for records, species by species and location by location, including the Sacramento-Yolo area. Last time I noted individual local birds that have been detected well south of here. I presented them as northbound migrants to Yolo, that is, spring migrants.
Now that fall migration is well underway, let’s look at some records of birds detected both locally and north of here, and think of them as fall migrants. To start off, recall two detection biases in the continent-wide network of radio signal receivers. One is that coverage is much better around Puget Sound than in the Sierras and Cascades, even though both regions are thought to be important sources of our fall migrants. Two is that there are many more records for waterfowl and birds of prey than for small birds.
The sheer mass of waterfowl records can bewilder at times. Our area is at the center of the most important winter waterfowl habitat in the West, and the records show that birds come here from all over the continent, even the Atlantic coast.
The travels of snow geese are well documented. Our birds are detected widely around California, the northwestern US, western Canada, throughout Alaska, the Canadian Arctic, and eastern Arctic Canada, e.g. Baffin Island, which is three thousand miles from here as the crow flies, and clearly much further as the goose flies. Some of those same birds continue on to Mexico.
Similarly, our greater white-fronted geese have been tracked from their breeding grounds in arctic Alaska and the central Canadian Arctic, throughout the Pacific states, and from (or to?) New Mexico. Ross’s geese have been tracked here from the shore of Hudson Bay, where they nest.
Our redheads have been detected in Alberta and Saskatchewan. I mentioned last time that Yolo area redheads have been tracked to southern Mexico in winter.
Among shorebirds, the locally numerous long-billed dowitcher has been detected around California, in eastern Oregon and Nevada, and near Anchorage, Alaska. Our dunlins have been tracked well enough to show that some of them travel from their Arctic Alaskan breeding grounds to the coast near Anchorage and south coastwise through British Columbia and Washington.
American coots come here from many points in western Canada and across Montana. Caspian terns have been tracked from near Portland OR, probably from a large nesting colony on the Columbia River. Turkey vultures travel in a broad band from western Washington to California. Our wintering American kestrels have been detected around northern and central CA, eastern Washington, and as far away as Missouri.
As noted, records for small land-birds migrating to or through Yolo are disappointingly few. Here are the detections I found for Yolo birds: common flicker—southern British Columbia; mourning dove—southwestern Alberta, Montana, Idaho, Washington and Oregon; willow flycatcher—lower Columbia River; American goldfinch—western Oregon and Washington; and purple finch—north coast near Eureka. Dark-eyed junco was detected on the Oregon border, in the Sierras, and north along the California coast. A few more include lazuli bunting—near Boise Idaho; white-crowned sparrow—Oregon and Idaho; golden-crowned sparrow—Alberta; Brewer’s blackbird—Washington and Oregon; red-winged blackbird—Washington and Idaho; and brown-headed cowbird—Pacific states west of the Cascades and central British Columbia.
Now go out there and find them. If you must stay indoors, visit explorer.audubon.org and click on tabs for “species” and for “location”, e.g. “Yolo County”.
— Michael Perrone, Conservation Chair