Tracking the Baja Birds, Watching the Hierarchy Unfold

Posted at 10:00 am January 25, 2008 by Michael Wallace Ph.D.

radiotrackingbaja.jpgRadio transmitters, along with more sophisticated GPS-satellite transmitters; attached to each wing, allow us to keep track of short and long distance movements. Trailing from each transmitter, vinyl tags display numbers large enough for the birds to be identified at some distance with binoculars whether the bird is sitting or flying. These “stud book” numbers are each bird’s personal ID and are never repeated.

Condor #261 is at the top of his game. The alpha male presiding over a small but growing group of 16 birds in the Sierra San Pedro Martir of Baja California, he enjoys his pick of perches, deference by others at the feeding sites and, apparently, his choice of mate. It was not always so easy for #261, in fact, he started at the bottom of the pecking order when he and 4 other condors, a male #259 and three females, older by one year, arrived at the release site in August 2002. He had been somewhere in the middle of the group in status, but when he was captured from a large aviary on transport day at the Los Angles Zoo’s condor breeding facility, he incurred an injury to his beak that left him in some degree of pain as he healed over the next few months. Conferring with the zoo’s veterinarian, we decided that the non-life threatening broken beak tip would heal on it’s own and he could retain his ticket on the small plane to Mexico.

Since a condor’s beak is the primary weapon of defense from other attacking condors he was automatically relegated to the bottom of the hierarchy when the 5 birds were placed in the large release site aviary. For over 2 months he could be seen feeding off to the side of the group or when the others were absent around the carcass. Any encounters with the others often involved submissive wing-begging displays that kept him under the radar of the more aggressive encounters of the other birds as they ironed out their social differences.

To test how the first releases would go in the new area, three of the five birds would be released first. When the 20’ by 20’ by 10’ high pen, attached to the larger 60’by 60’ by 30’ aviary door was opened to capture the first release candidates, #261 was, by chance within the first group. Since we didn’t know if his low status would have any relevance to when he was released or which group he was released in, he was released with female #18 and Male 58, the two top ranking birds in the group. Remaining behind in the flight pen were #220, the female next in status and the shy female #217 who stayed in the back ground and would have been at the bottom of the hierarchy of the group if it wasn’t for #261’s beak injury.

Our first release turned out to be a near disaster. Golden eagles, a species known to kill condors on occasion, drove both #218 and #259 to the ground with a series of unfriendly strikes, causing the female to remain in the bushes over night and the male to head south. I spent the night with the downed bird and at dawn she had climbed into a small tree seemed fine but headed south low along the ridgeline as well. Neither of the attacked birds would attempt to gain altitude in thermals presumably in fear of further interactions with eagles. Without altitude they could not get the lay of the land so could not orient back to the release pen.

Over the next two weeks they both wandered south separately without food or water. Typically released condors hang close to the release point orienting on the other condors and locking in on the food and water placed out on the release area. Eventually they both had to be trapped back into captivity, one in the chaparral at 3:00 AM about 17 miles to the south and the second that flew nearly as far in another direction and had to be grabbed 50 feet up in a pine tree after dark. Meanwhile our subordinate condor, #261 did exceptionally well. He somehow escaped the wrath of eagles, learned to soar and successfully oriented back to the release pen. Not wanting to have a single condor free through the winter we trapped him and placed him in with the other condors but by then he had learned the area and was flying quite well. Stay tuned for the next installment that looks at springtime releases and the adventures of #261!

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One Response to “Tracking the Baja Birds, Watching the Hierarchy Unfold”

  1. Tom says:

    Hi,

    not a comment, but a question. I’ve seen condors at the Grand Canyon. Can you tell me how big there head is? I know, strange question, but they seem huge! They seem like they must be 12 inches from beak to back of head.

    Thanks,
    Tom

    Editor’s note: A California condor’s head is approximately 6-8 inches in from the beak to the back of the head. Thank you for asking.

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