2010 Dipper Article

8/3/2010 article for Chat by Barbara Massey

American Dippers in Ashland Creek

It is well known that dippers reside on (and in) Ashland Creek in Lithia Park. For a dozen years, Bob Quaccia has led a dipper count of the population in mid-winter from the Main Street bridge to the reservoir. The walk is always attended by a group of enthusiastic birders and has become and a tradition for RVAS. I have somehow managed to miss this event year after year, but finally made it last January. It is lots of fun, but the information gathered has sometimes been puzzling and the number of birds seen has varied a lot from year to year. So Bob and I got together and decided to set up something new and different that we hoped would help us learn more about the birds on the creek.

Not a whole lot is known about the annual cycle of this bird, understandably, as its habitat and behavior make it difficult to study. Its name comes from the ‘dipping ‘ behavior it exhibits while standing on a rock (perhaps contemplating its next move). The best-known facts are that it is always closely associated with a fast running mountain stream, forages in the water on and under rocks for insects, and is able to literally walk under water on the bed of the stream. It breeds at high altitudes in the west, building a bulky nest next to the water on a ledge or on a rock in mid-stream, and sometimes even behind a falls. Winter observations are nil, as snow blankets the habitat and often the birds move downstream.

In Ashland we have a unique situation – much of the dipper’s habitat on the creek is in a low-altitude snow-free zone and there is access by road or path all year for 1½ miles through Lithia Park. So we decided to begin with an observational study through the nesting season, starting in late April. By dipper standards, this could be mid-season, as they often breed early in the spring, and in fact Harry Fuller had already seen an adult carry off a fecal sac from a nest under the Main Street bridge. But other commitments prevented an earlier start, and dippers often nest more than once during a season with the peak time in June. So we invited a few other enthusiasts (Gwyneth Ragosine, Jeff Tufts, Eric Setterberg, and Larry Wright – plus Ron Ketchum who soon had to drop out) to join us in April to search for nests and then do a weekly watch to document the breeding cycle. We found two nests and here is a brief chronicle of each:

On 4/23/10 a nest was already in progress under the bridge, perhaps a second for the pair that Harry haed seen, and the adults were busy carrying nesting material into a small drainage pipe up on the curve of the culvert (see photo). It was on the east side and not observable directly, but Eric donned a full-dress rubber suit and waded in the very swift stream to take the accompanying photo. Nest building was finished by 5/8 and there followed a long period of egg-laying and incubation, and we could not tell when exactly one left off and the other began. Hatching occurred on 5/24 and until 6/4 there were regular feedings of chicks in the nest. Then there was a puzzling lull in activity and we thought the nest had failed, but on 6/18 a fledgling was standing alone on a rock across from the nest. We watched as it tentatively foraged along the rocks and in the water but never saw an adult in attendance. It was seen alone again two days later and then disappeared from our sureveillance. This was considered odd behavior, as dippers are reported to teach their chicks to feed, and feed them while they are learning.

The 2nd nest was at the upper end of the creek trail. It was sighted by Eric and Gwyneth on 5/8 and was a bulky structure on a ledge below the culvert where the road crosses the creek at the reservoir picnic area (see photo). Incubation was presumably well along, as the pair began feeding bouts on 5/14. The incubation period is said to be 3-4 weeks and at what we calculated was 3 weeks we began a daily watch to try to observe fledging.  The big day was 6/8, around 24 days post-hatching, and Jeff was lucky enough to arrive shortly after two youngsters fledged. The nest was gone – it had probably fallen into the creek as it was teetering noticeably during feedibngs the previous day. And the fledglings were standing on a rock in the stream below, soon to be fed by their parents. They were fully feathered and able to go into the water immediately. We were able to find them several times during their first week on their own, always upstream from the nest and often at a large rock-rimmed pool about ½ mile north of the road. And then they were lost to us.

We learned a lot from our watches, more than I can detail here, but still have much to determine and will continue next year. Meanwhile we want to have dipper walks more often to try to keep track of the year-round actions of these Ashland Creek birds.

On Saturday September 25 we will do an autumn walk upstream as Bob has done in the past in winter. We invite any and all who are interested to join us. Thanks to the Ashland Parks and Recreation Dept. we now have a good map of the creek, and will plot dipper locations and numbers. Meet at 8AM at the lower end of Lithia Park on Winburn St. for the 1st fall count.

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