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Spring migrants such as rufous hummingbirds show up on the coast before making an appearance in the Rogue Valley. [Photo by Christine Pitto]

Spring migration starts earlier on the coast

In early February, rufous hummingbirds and turkey vultures were spotted in Coos Bay. Tree swallows were in Newport. What’s wrong here?

Spring migration is warming up, and it’s nothing but chilled dark-eyed juncos here in the Rogue Valley. It seems we have been forgotten.

Not to worry. This is normal if a bit frustrating. Migration of land birds starts up along the coast. Rufous hummingbirds are one of the first. Despite the winter storms still rolling in off the Pacific, the northward push is unstoppable. But it’s not as suicidal as it seems. Freezing weather seldom reaches the beach, while here in the Rogue Valley, the threat of killing frost keeps gardeners inside with few thoughts of lettuce or tomatoes.

But what about flowers at the coast this time of year? There aren’t many. The purple salmonberry flowers that rufous hummingbirds favor are just swelling in the bud, but there is salal. The hillsides and headlands are covered with the impenetrable thickets of salal with thick evergreen leaves, and they are blooming, not profusely perhaps. But it’s apparently enough to open the door to hummingbird migration.

I’m sure the early blooms in the backyards of towns along the coast help, too, but before the state was settled by Europeans, salal was about it. Migration patterns were established long before the Europeans arrived. Now in the Rogue Valley, just try to find a native plant in bloom. Patience.

You can bet the next sightings of rufous hummingbirds in Southern Oregon will be in Josephine County. Spring wildflowers appear a few days earlier in Grants Pass and the Illinois Valley than in Jackson County. Next, the parade of northbound hummingbirds will be in western Jackson County, usually along Sardine Creek. Then and only then do they show up at the feeder in my backyard in Medford.

I’ve watched this sequence of arrivals repeat itself every spring over the last three decades, seldom with any variation. The wave of migration begins along the coast and slowly works its way inland. And it’s not just rufous hummingbirds. The pattern is repeated by swallows and vultures. It’s not flowers this time, but it’s the availability of flying insects and flying conditions that gradually improve from the coast inland that regulates the timing of migration for these species.

The pattern continues with the insect eaters that search for caterpillars and spiders among the vegetation. Nashville warblers, Black-headed grosbeaks, and Western tanagers all tend to show up in Josephine County before Jackson County. Their arrival is tuned to bud break among the alders and oaks.

Migration isn’t perfectly tuned. Late storms or a severe cold snap can take a toll among the vanguard that leads the parade. Early tree swallows, in particular, are known to suffer mortality due to inclement weather that clears insects from the air.

Still, this highlights just how close migrating birds push the envelope. There is a rush to be first. The penalty must be very high for those arriving late on the breeding grounds. The punishment is likely meted out in the form of a territory of lesser quality and the failure to attract a mate.

So, if you are impatient for the arrival of spring, try leaning a little to the west.

— Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.

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