This month we celebrate the eighth anniversary of the Wednesday bird walks along the Olympic Discovery Trail in Railroad Bridge Park.

The walk leader is Bob Boekelheide, director of the Dungeness River Audubon Center and our local birding expert. I asked Bob about the history of the walk.

Dave Jackson: I have a favorite memory from early fall in my first year here. I heard a faint call from a varied thrush and pointed toward it.

No one else on the walk had heard it, and you were skeptical, as it was too early in the season for varied thrushes to have come down from the foothills.

A few minutes later, to my everlasting delight, the thrush flew directly over our heads from the direction I had pointed.

Bob Boekelheide: Extra eyes and ears can be quite helpful. Several of our regulars are excellent spotters. Margaret Levitan once spotted three white pelicans flying on the horizon, the only time on the walk we’ve ever seen that species. This summer, Ken Campbell spotted a screech owl almost perfectly camouflaged against a tree.

Even the birds themselves can help. Steller’s jays made a fuss behind us one day and we retraced our steps to find a saw-whet owl sitting in the shadows close to the trail.

Dave: Do you have a favorite memory?

Bob: There have been so many, it’s hard to single one out. A favorite experience repeats itself. I train my spotting scope on an attractive perched bird, like a tanager or waxwing, inviting everyone, even passersby, to look. It’s quite satisfying to hear the oohs and aahs when people see a bird in a way that they have either never seen it before or only seen it in a picture.

Occasionally there’s considerable action. Earlier this year, although a bit gory, we saw a merlin catch a junco, pluck it in a cloud of feathers, then have an early lunch.

Dave: We do more than just get cool looks at birds.

Bob: Absolutely. This is citizen science at work. Weekly I record each species seen or heard and how many we find. Later I enter that info into a database for later analysis. As good scientists, we strive to minimize variables, walking the same route at the same time of day (8:30 a.m. start) each week.

Dave: But the weather differs.

Bob: The walk never has been canceled, no matter what the weather. Bad weather reduces our counts, as birds seek cover and stay quiet. I try to adjust for anomalously low counts when analyzing the data for trends, by taking the monthly high count for each species rather than averaging weekly totals.

Dave: Any interesting trends?

Bob: Many. For example, bald eagle numbers are low in July and August, as many of them have gone north to feed where the salmon are more plentiful. Eagle numbers increase through the fall until they have all returned by December, coinciding with local runs of cohos.

Song sparrow is the only species we’ve found on every walk. We’ve found another dozen species more than 90 percent of the time: robin, towhee, Steller’s jay, house finch, house sparrow, crow, nuthatch, both chickadees, starling, junco and golden-crowned kinglet.

Dave: Those are all local residents, except robins, which are migratory.

Bob: Data on robins are fascinating. We get relatively high numbers in October through December, which we think are due to birds wintering here after breeding farther north. Robin numbers drop off in January, perhaps due to the weather.

Our peak numbers for the year are in February, when sizable flocks are fairly common. We think this surge is due to early returnees from the south that are eager to claim the best nesting territories. Robin numbers are low in the summer, even when berries are ripe along our walk. We don’t yet understand where they go.

Dave: Any recent developments?

Bob: As of June this year, we never had seen or heard a Eurasian collared-dove on the walk. By August, they had moved into the neighborhood as they did in the Dungeness area three years ago. We now find them regularly, usually on telephone wires near Runnion Road.

Dave: Anyone is welcome to join us.

Bob: Yes. Aside from regulars and assorted local residents, we’ve had visitors from nearly all 50 states and several continents. Afterward they report having had a fun time. We have loaner binoculars in the River Center.

Amazingly this walk is still free. I encourage folks to check out the center after the walk. It has a lovely donation box.

Author Dave Jackson is series coordinator and Web master. Send comments to him at editor@olybird.org or 683-1355. Details of classes and trips are on Web site www.olybird.org.