Thom Lord— 7 December 2006 — in California Condor Restoration ShareGreetings, Notes from the Field readers! The Peregrine Fund’s condor crew has been running full bore for the last month, swarming the Kaibab Plateau in an attempt to document as much of the birds’ movement and feeding activity as possible while the hunting season is underway. With the help of hunters and the Arizona Game and Fish Department, an extraordinary number of gutpiles and carcass remains have been recovered or turned in. This is extremely important, giving us information as to how many of these remains contain lead fragments, and preventing condors from being exposed to these fragments when lead ammunition has been used (for more information on lead and condors, see last month’s NFTF and the articles available at http://www.peregrinefund.org/pdf_articles.asp). We have also continued our fall trapping effort in order to assess lead levels in individual birds as they return to the release site.
While in the field, condor biologists have a number of tools at their disposal to locate the birds, and therefore determine where (and on what) they might be feeding. In addition to the standard radio-transmitters that every condor wears, many birds in the population also wear wing-mounted GPS transceivers which were provided by Arizona Game and Fish. Each morning, we download the previous days’ locations of each of these birds, paying special attention to concentrations of “hits” that might indicate a feeding location. This method has proven quite efficient, and we have located a number of condors near carcasses and gutpiles this way.
We can also use GPS data in a more general way, getting an idea where the most condor activity in a particular region might be, and concentrating tracking efforts in those areas. It’s then up to the biologists, using radio receivers and their senses, to find the birds and/or carcasses. The Peregrine Fund crew has become quite proficient at this, using signs such as raven and eagle activity to clue them in to the location of carcasses (in the same manner that condors themselves use these signs), and often finding the carcasses before the condors do. We collect most of the carcasses and gutpiles that we locate, and x-ray them to determine the presence or absence of lead fragments. If any condors are thought to have fed upon a carcass we know to contain fragments, those birds are put at the top of the list to be trapped and tested for lead exposure.
We were able to trap a number of these high-priority birds last month for testing, and did see evidence of lead ingestion in a few cases. We have administered chelation therapy for lead exposure to seven birds so far this fall, and all are doing very well. The Kaibab hunting season ends on 3 December, but we will have to remain vigilant for a number of weeks after that, as we continue to trap and test the remaining birds in the population. We continued to speak with a number of hunters on the Kaibab throughout November, and many were using the free non-lead ammunition provided by Arizona Game and Fish. It’s still too early to tell how this year’s rate of exposure will compare with previous years, but we’ll continue doing everything we can to minimize that exposure, and keep our fingers crossed in the meantime.
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