Denny: Songbirds start annual migrations

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With July out of the picture, much is going to change in the natural world through August.

Remember that bird migration to the south that has been ongoing since late June? Well August is the center of passerine migration. These are the song birds like sparrows, warblers, orioles, vireos, hummingbirds, tanagers, grosbeaks and many flycatchers/kingbirds.

All these small bird species are headed south into Mexico and Central America. Fall migration is a long, slow process that takes months because the weather is mild, forage base is not restricted and there is ample cover.

There are two separate movements of song birds. The adults and some young start drifting south in late July. In August mass movements of young and a few adults head out.

This is also the season that many post-breeding adults just wander seemingly aimlessly up and over mountains, across rivers and along the coast.

All this migration is triggered by one thing: the declining length of day light that follows the ancient cycle and shortens with each passing day. After June 21 there is a certain pressure that builds in birds, pushing them out of their breeding territories and overland in a southward direction.

There are always exceptions in the natural world, and this month I would like to share a story of one of these amazing events.

Back in 1997 my wife and I were doing the Oregon Breeding Bird Atlas in south central Malheur County, Ore., when we came across a small flock of finches that up until that moment we had never expected to find. It was near Dowell Reservoir and the birds were lesser goldfinches, a species once considered rare anywhere outside of northern California, Nevada or southern Idaho or the northern Great Basin.

As timed passed, these small finches began to explore new territory, and with droughts and changing weather patterns they began to spread to the north and east. In the intervening 16 years this species is now breeding here in Walla Walla County.

We found the first small flock of five at Starbuck only six years ago. They now are regular in Dayton, Pomeroy and on into Asotin County where we have seen winter flocks of 40-plus birds. This spring we found them nesting in the trees just back of the fishing wall at Little Goose Dam for the first time.

Lesser goldfinches are adapting to the drier conditions and working their way north. They are feeding on knapweed, yellow star thistle, Canada thistle and teasel, to name a few invasive weeds that these birds like. So as land loses its native habitat and is covered with invasive weeds these beautiful finches profit and push out their distribution into new areas.

Keep your eyes open for a small, bright-yellow-breasted, black-crowned and green-backed goldfinch. This is a bird your parents never saw in this region while they were out and about.

Keep your eyes and ears open as once again wildlife moves with the seasons across the face of this planet. And as fall approaches many animals are on the move and are in need of cover and water.

Remember, life is good!

Mike Denny is president of the Blue Mountain chapter of the National Audubon Society. He can be reached at m.denny@charter.net., or by calling weekdays between 6-8 p.m. at 529-0080.

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