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Swallows on Ten Mile Bridge

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  • Kate Marianchild
    Forward of a message from Erica Fielder
    Message 1 of 1 , Jul 13 2:11 PM
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      Forward of a message from Erica Fielder

      >> Yesterday, July 4, Larry Knowles and I took the canoe and paddled
      >> under
      >> the Ten Mile Bridge to count the cliff swallow nests that, as far as
      >> we
      >> could tell, were being used this year. We counted 1,185 of them.
      >> Assuming that each nest is maintained by two adults and that there
      >> are
      >> also unmated individuals in the colony, we estimated there were close
      >> to 3,000 birds involved, not counting chicks. We saw lots of little
      >> heads peeping out of the entry spouts to the nests.
      >> Over the 15 years I have lived at Ten Mile next to the bridge, I have
      >> noticed that the swallows move, year to year, to different sections of
      >> the bridge to make nests. Two years ago they nested on the northern
      >> third of the bridge. last year, they nested on the southern third.
      >> This
      >> year they are nesting on the center third. I think they rotate to
      >> reduce possible infection from disease, mites, lice, etc. You can see
      >> thousands of old nests and parts of nests in the unused sections. I
      >> expect that next year, the swallows will use the nests on the northern
      >> third of the bridge, that is, unless CalTrans disturbs them too much.
      >> I
      >> think bridge construction begins in 2006.
      >> To my surprise, the swallows built twice the number of nests on the
      >> more exposed side than on the protected east side of the bridge. I
      >> have
      >> observed just the opposite in years past. Does anyone else have
      >> information on this? Since the new bridge will be built on the east
      >> side of the existing one, perhaps the swallows are already responding
      >> to CalTrans disturbance. There has been some activity on the east side
      >> over the years as CalTrans drills and explores the river.
      >> After our count, we observed the birds for about an hour from the
      >> beach
      >> on the south side of the river. A male kestral spent some time perched
      >> on the telephone wire that hangs close and parallels the bridge. For
      >> at
      >> least 20 minutes he periodically flew beneath the overhang to the
      >> nests and appeared to be looking into the nests. Sometimes he actually
      >> landed and clung for a moment to the entrance of a nest. Once I saw
      >> him
      >> stick his head into a nest. During the time we observed him, he caught
      >> nothing, but he sure looked like he was trying to grab a chick. During
      >> this behavior, clouds of swallows followed him at a distance. They
      >> never got close to him, like blackbirds would do. Even though these
      >> nests appear quite protected in their position above the river, they
      >> are vulnerable to both predators and humans.
      >> I sure hope CalTrans has made adequate nesting sites with a flat,
      >> rough
      >> vertical surface and an overhang so the new bridge can support this
      >> huge population.
      >> ************************************************
      >> For more information on Erica Fielder Studio,
      >> please see my two websites:
      >> www.ericafielder-ecoartist.com
      >> www.birdfeederhat.org
      >> Erica Fielder Studio
      >> P.O. Box 1075,
      >> Mendocino, CA 95460
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