2012 Dipper Article

Dipper article for Chat/KBO 2012

American Dipper study on Ashland Creek

by Barbara Massey

bmassey@mac.com


The 2012 nesting season was so full of new information it cannot be covered in a short article. But here’s a try. And if anyone wants more information, please contact me or one of the other team members. We will probably provide you with more info than you could ever want, as we love to talk about dippers. Our group this season consisted of Eric Setterbeg, Jeff Tufts, Frank Lospalluto, Barbara Massey, Bob Quaccia, Gwyneth Ragosine, Sally Jones, and Kathy Simonsen.

After observing the dippers in Ashland Creek for two seasons and finding no nests between the Main St. culvert and the spillway at the reservoir (a distance of 1 ½ miles), it became clear that there was a dearth of good nesting sites. This portion of the creek lacks the stream habitat that dippers usually use, like banks with burrows, mid-stream rocks that are safe from squirrels, and natural waterfalls behind which they like to build. It is the understructure of  bridges where we have found most nests. But many of the bridges do not have suitable beams that could support nests. So Eric Setterberg built a variety of nesting structures -including platforms, nest boxes, and a polyethylene tube and on March 3rd  he and Frank Lospalluto installed them under foot bridges between Pioneer St. (the entrance to park headquarters) and the reservoir.

Pairs used two of last seasons’s nest sites (the reservoir spillway and a culvert under Main St. and a new on on a buttress of the Pioneer St. bridge, on the entry road to park headquarters). But this last one was partially built but then deserted, and shortly thereafter we found a pair (same pair?) building a short way upstream in one of the new nest boxes. It was under the 3rd bridge downstream of the reservoir. We then watched all 3 active nests through two breeding cycles, all of which produced fledglings.

Banding was stepped up this year and in all there were 5 sessions with 9 dippers color banded – 4 adults and 5 chicks. John Alexander of KBO did the trapping and banding, with help from his staff. And what a boon that was for us, as being able to identify individuals gave us a whole new understanding of the breeding cycle, particularly at the 3rd bridge where the adults and both sets fledglings were banded.

The 3rd St. bridge site is worth a detailed account. On 3/16 we found a near-completed nest. It was finished by 3/23 but egg laying apparently did not occur for several weeks. By 4/12 the female was incubating eggs, and the male was observed busily finding larvae in the creek and bringing them to her. When not feeding himself or his mate he was usually standing vigil on a rock in the stream below the nest. Hatching occurred around 4/18 and a week later both adults were color banded. This date was chosen for two reasons. When parents are feeding young there is almost no chance of desertion and they are also easy to catch by mist-netting as they are constantly bringing food to the nest. When the 3 chicks were 10-12 days old (4/30) they were taken from the nest and color banded. This is the optimal time in their development to band because the legs are long enough to hold the bands and the chicks are not yet able to clamor out of the nest. While their chicks were being banded the parents waited on rocks below with food in their beaks and immediately resumed feeding after we returned the chicks to the nest.

A week before the first brood fledged, the female was seen carrying nest material up under the bridge and also displaying to her mate. He seemed fully occupied feeding the chicks but, as later events testified, took time out for copulation. Fledging took place on 5/9-5/10 and the male became the sole feeder of the chicks as his mate was already incubating the 2nd clutch. On 5/11 Eric climbed down under the bridge and to photograph the new nest and found it had been built on the roof of the nest box. (PHOTO) The female was incubating 4 eggs! She built the 2nd nest while the hatchlings were growing and had already begun to lay eggs before they fledged. (We knew from the literature that 2nd nesting is not unusual for dippers, but is usually in the refurbished first nest and not until begun until the fledglings are feeding themselves.) The male did ALL of the feeding of the 3 fledglings for a week. Then he returned to take up vigil on his rock below the nest. The fledglings were seen foraging on their own on 5/18, 8 days after leaving the nest and several times thereafter.

On 5/25 two chicks hatched in the 2nd nest – we don’t know what happened to the other two eggs that were photographed earlier. Both parents fed the chicks until they fledged on 6/17, 23 days after hatching, but the male took over as soon as fledging occurred. On 6/22 he was seen downstream feeding the two fledglings, and farther downstream the female had resumed her non-parental life style. She was standing on a rock in mid-stream preening, then foraging in a desultory way, then basking in the sun. It is difficult to refrain from anthropomorphizing about this situation. She looked so serene, alone to do as she pleased after two intense breeding cycles. Did she know her mate would take on the feeding and care of the fledglings? It would seem so. Her job was to build nests and incubate eggs, with some occasional feeding duties. And after that day we saw her no more. Her achievement – 5 chicks successfully hatched and reared. His role – most of the feeding of the hatchlings and total care and feeding of  the fledglings. This is not the typical scenario as both parents usually feed both hatchlings and juveniles.

Our plans for next year include replacing the platforms with nest boxes, using the design that worked so well at 3rd bridge; adding a few boxes to bridges downstream of Pioneer St.; investigating a web-cam for one of the nests, and continuing to observe and band parents and chicks. We expect to continue this project for several years, as each year brings a few answers and a lot of new questions about the life history of the dippers of Ashland Creek. For more information about the 2012 season visit our website – lithiadipperwatch. Frank is an excellent webmaster and although the 2012 field notes have not been entered since early June, they will be, not that the breeding season is over and he has some time.  Anyone who is interested in spending time dipper-watching is welcome. Contact any member of the current team and join us. It is addictive.

Photos
double nests
reservoir nest
banding chicks
banded adults with chicks

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