Bird Migration around Vernon; What Are Those Little Birds with Black and White Heads?

It's the later half of April or early May and suddenly your bird feeder is surrounded by ten or fifteen little brown and gray birds with strikingly obvious black and white stripes on their heads. They look a bit like mice as they jink around on the ground eating seeds. They move so that each bird has an individual space around it, occasionally invaded by a contender, but fights between birds are brief and unspectacular. What are these little birds? Why are so many in my yard when last week there were none?

These birds are White-crowned Sparrows (Zonotrichia leucophrys) and they are re-fueling during their migration through the lowlands of the Okanagan Valley. In a few days they will have moved on to their breeding grounds across northern and central British Columbia. A few will migrate up into our local mountains to breed in the brushy edges between the clumps of subalpine forest. A very few might remain in the Valley to nest, but lowland nesting for this group is a rare event.

What you are witnessing is the spring migration of White-crowned Sparrows through the Okanagan Valley. In their classic study of the birds of the area*, the Cannings brothers point out that obvious migration events are rare in the Okanagan, but the relatively compressed spring migration of White-crowns is a classic example of such a movement. The majority of the 300 species of birds that annually visit the Okanagan Valley are migrants too, but migrate in quiet, less obvious ways, many of them songbirds that pass largely unseen by all but the most dedicated birdwatchers as they (the migrants) move through the fields and forests on their way to nesting areas. Many of our waterfowl that spend the winter on our lakes are also migrants, but unless you go out of your way to survey ducks and geese on local water bodies, the migratory arrivals and departures are not as obvious as the sudden arrival of the White-crowned crowds to your yard.

White-crowned Sparrow at a BX feeder in April 2016. Photos by Chris Siddle

Enjoy "your" White-crowned Sparrows while you can, for they will not tarry long on their way north. Consider putting out a little extra seed for these weary travellers, and certainly some pans of fresh water so that they can drink and bathe. Make an extra effort to shoo away the neighbours' cats to keep these sparrows as safe as you can, for each sparrow is driven by migratory forces that scientists, let alone the rest of us, are only beginning to understand.

Other examples of spring migration to look for in the Okanagan Valley:

1. the arrival and movement of Yellow-rumped Warblers through the lowlands. These beautiful "butterfly birds, named for their many colours and restless foraging, are most obvious when cool, wet weather forces them out of the forests to look for food in low bushes, grassland edges, and marshes.

Yellow-rumped Warbler in bushes along Deep Creek, Larkin Cross Rd., April 2018.

2. the visitation of swans to the Deep Creek floodplain between Armstrong and Head of the Lake. Lately the corn field at O'Keefe Ranch has been a very productive spot for over a hundred Trumpeter Swans to gather to feed in March and the first half of April. Among them will be a few Tundra Swans as well. By mid April, depending upon the weather, both species will have continued their migration to the north, the Tundra Swans breeding on the tundra of the Canadian arctic.

Trumpeter Swans flying towards corn field at O'keefe  Ranch, March, 2017

3. the sudden appearances and very short visits of the dark hooded little Bonaparte's Gulls at Okanagan Landing-Okanagan Lake, Swan Lake, and Otter Lake.

There are many other examples of migratory birds coming and going through the North Okanagan. And, of course, there are birds like American Robins, which flock together in winter, overwinter in roving groups looking for food sources, and disperse into neighbourhoods with the first good weather in early spring. Then there are the birds that winter here from elsewhere. Our huge flocks of Bohemian Waxwings originate as pairs and their young leave their isolated Boreal Forest muskegs to gather in huge flocks to travel to the Okanagan, arriving in late November or December and visiting our local fruit-producing bushes, shrubs, and trees, especially the Mountain Ash trees, stripping the fruit and befouling the ground beneath as each bird rapidly digests the frozen fruit. By the end of March, most years, the Bohemians vanish once again, back into their forests and muskegs, changing their party life-style to become, for the spring and summer, responsible monogamous parents.

Bohemian Waxwings stripping a bush of berries, Highland Rd., s. of Vernon, Dec. 2016

*For more about movements, migratory and otherwise, see Birds of the Okanagan Valley, British Columbia by Robert A. , Richard J. and Sydney G Cannings. 1987. Royal British Columbia Museum, available in public libraries and possibly second hand bookstores. Pages 352-3 specifically cover White-crowned Sparrows, while pages 53-6 contain an invaluable summery of bird migrations and other activities through the calendar year.