[obol] creeper behavior

Wed Aug 1 12:33:31 PDT 2007

Dan,
    I went back to the creeper tree this morning.  I wasn't able to climb quite as high as the spot where the creeper flattened out against the trunk, but did not see any evidence of ants anywhere in the vincinity, including on the trunk of the tree.  So I'm inclined to think the bird was either simply sunbathing, or else using the sun as a means to dislodge parasites. 

Darrel 
  ----- Original Message ----- 
  From: Dan Gleason 
  To: Darrel Faxon 
  Cc: Obol 
  Sent: Tuesday, July 31, 2007 6:56 PM
  Subject: Re: [obol] creeper behavior

  Interesting observation. I have not seen anything like this in Brown Creeper but two ideas come to mind. First, as you indicated, it might simply be sun-bathing which has been reported for Brown Creeper. Given that it was doing this on the same location, another idea comes to mind and that is the possibility of anting. I don't believe I have ever seen reports of anting behavior in Brown Creepers but it certainly seems like a possibility. Did you by any chance note if there were any ants on that location? 

  Most anting usually takes place on the ground where the ants are more prevalent but a Brown Creeper on the ground would be most unusual.

  If anyone is not acquainted with anting behavior, it has now been reported for several species. It takes two forms. The passive form of anting involves a bird spreading out over an ant colony and allowing the ants to crawl over it and through its feathers. Most ants are very aggressive, biting and casting off other species of insects. The bird is aided by allowing the ants to remove lice and other parasites. I have photos of a Scrub-Jay doing just this in our backyard two years ago. An active form of anting is when the bird takes a more deliberate role. Ants are crushed and worked through the plumage. Presumably, the formic acid in the sting of the ant acts as a natural pesticide, assisting the bird in eliminating feather lice or other ectoparasites. The jay we observed in passive anting also did some active anting. My photos look as if the bird is simply preening under its wing but we watched it put up ants in its bill and work them through the feathers. Crows, orioles, blackbirds, other jays and several other species have now been reported as anting, a behavior first reported by Audubon. Ants are not the only thing used and mothballs, orange rinds and similar objects have also been reported to be used.

  As an aside, the aggressiveness of ants is useful, and actively recruited, by another species - aspen trees. When the leaves of the aspen are still in bud and not yet open, small nectaries near the leave buds exude a sweet substance that is attractive to ants. As ants gather to drink this sweet liquid, they grab tent caterpillars in their jaws and throw them off of the tree. Large numbers of these caterpillars could devastate the aspen when the leaves are just emerging. By the time that the leaves are fully open and actively photosynthesizing, the trees have also produced a significant amount of chlorophyll in the thin bark tissue. If all of the leaves are not eaten by caterpillars, the bark can sustain the tree through the season. That means that ants are no longer needed and the tree expends no more energy attracting them and the nectaries dry up.

  Nature is full of fascinating relationships like this if we take the time to look.

  Dan Gleason

  -------------
  Dan Gleason
  dan-gleason at comcast.net
  541 345-0450

  On Jul 31, 2007, at 6:22 PM, Darrel Faxon wrote:

    OBOLites,
          As I almost never see Brown Creepers at Thornton Creek, Lincoln County during the summer months, the one today was remarkable in any respect, but  its behavior was exceptionally noteworthy.  When I first noticed the bird, it was at the base of a large alder about forty feet from me, and well below eye level.  The morning sun was shining directly on the trunk of the tree.  The tree leaned a bit towards horizontal, rather than being completely straight up and down, and about eight feet off the ground where the first limb branched off, there was a little pocket whch was a bit more horizontal.  As the creeper hitched itself up the tree, when it came to this spot, it suddenly spread its wings and flattened out against the trunk of the tree.  It remained motionless in that position for close to a minute.  In doing so, the bird itself seemed to disappear against the trunk, and all that showed were the two crescent wing bars, which took on the appearance of a marking or growth of lichen on the tree.
          I would have thought that such an action was taken in response to the presence of a predator, except for two things.  One, there were a number of other creatures nearby that would have assumed defensive measures had a predator been nearby, but they went right on with their activities in a normal manner.  A Willow Flycatcher, Song Sparrow, and Townsend's Chipmunk all were within twenty feet of the creeper and showed no signs of alarm.  Two, after the creeper resumed movement, it worked its way around the back of the alder, came out again near the base of the trunk, hitched its way up to the same spot, and repeated the performance: wings spread out, body pressed closely to the trunk, and motionless.  This time it moved its head a bit more, as if preening.  Then after about 30 seconds, it flew to another tree and went on about its normal feeding pattern.
          Has anyone else seen creepers act like this?  Any suggestions as to what the bird might have been doing?  I have two postulations:  One is that the bird considered me a predator, especially since I was above it on the bank, looking down.  I rather doubt this idea.  The other is that the bird was exposing itself to the bright sunlight in response to parasites.  This idea seems plausible, especially since on both occasions, the activity included what appeared to be some brief preening following the spread wing act.  In any case, it was very interesting, and something I never expected to see.
    _______________________________________________
    obol mailing list
    obol at lists.oregonstate.edu
    http://lists.oregonstate.edu/mailman/listinfo/obol

    To unsubscribe, send a message to:
    obol-leave at lists.oregonstate.edu.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.oregonstate.edu/mailman/private/obol/attachments/20070801/1d143486/attachment.htm 