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The Peregrine Fund Notes From The Field
May 2007
Eddie Feltes — in California Condor Restoration    Share
Vermilion Cliffs Nest Site
Vermilion Cliffs Nest Site
Greetings Notes from the Field readers! The warm air and steady winds that usually blanket northern Arizona during the month of May, sure showed up in 2007, allowing consistent routine flight travel and optimal foraging conditions for the condor population. The flock has been free foraging on wild bison carcasses and mule deer on the north Kaibab Plateau, elk south of Grand Canyon National Park in the Kaibab National Forest, a bighorn sheep ewe in the Grand Canyon, and domestic sheep and cattle carcasses north of the release site in southern Utah. It is this bountiful food supply, as well as the 90+ degree days that make condor viewing so difficult at the release site in the Vermilion Cliffs. It is not uncommon to have only a handful of the 56 free flying condors roosting at the proffered-food site during this time of year. But if in the area, bring a high powered scope just in case; on average there have been 15-20 birds present throughout the month of May.

A realization that our field crew has come to understand over time has been the prioritizing of tracking/monitoring duties based on changes in individual bird behavior, condor/human related instances, odd travel behavior, or whatever seems out of the ordinary for any reason. Having an experienced population of birds, including some that have been living in this region for over 10 years now, as well as an experienced crew on the ground that is quick to red-flag odd/unhealthy behavior in condors, allows for us to manage this dynamic species for the greatest success in this rough terrain quite efficiently. In the past, the month of May has always had our focus on the monitoring of condor nest sites, as wild producing pairs are, for obvious reasons, quite attractive and demanding of our attention as condor biologists. But with an ever growing population of wild and released birds, along with an ever increasing range of travel, crew duties this May were juggled between monitoring of the six nesting attempts and routine tracking of the wild condors, thus ensuring survival.

Nest site of Condors 133 and 158.
Nest site of Condors 133 and 158.
Some of you may recall from the March notes, that the probability of Condors 133 and 158 hatching a chick this year was unlikely, due to female Condor 195 nesting in such close proximity. And as expected, both nests failed due to inconsistent attendance of the potential eggs being split between three birds. Condor 195 gave up attending to her nest cave shortly after the estimated lay date due to not having an exclusive male to relieve her from incubation for foraging. And the pair 133/158 failed this year, also due to irregular incubation of our only visually confirmed egg, as male Condor 158 was trying to tend to both nest caves. Hopefully next year “the third time is the charm” will be the statement for this pair, as it has been for female Condor 119 and female Condor 127 in years past. The first nesting attempt of pair Condor 253 and Condor 223 also failed early. Both condors slowly tapered off in attending to the nest cave believed to house an egg laid by female Condor 253 just two weeks after the assumed lay date, for unknown reasons. This behavior is not too uncommon for new pairs, based on data collected over years of monitoring the wild Arizona population.

Nest site of Condors 210 and 134.
Nest site of Condors 210 and 134.
Of the six potential active nests, observations from both crew on the ground as well as GPS locations, indicate three are still active. Including two nest sites that could contain condor nestlings, based on estimated egg laying dates. All three current active nesting pairs have the female of each pair suited with a GPS mount allowing us to assess nesting progress via specific behavioral movements and foraging/travel patterns. Condors 127 and male Condor 123 are still making routine travel to and from foraging and nest cave sites, as well as female Condor 210 and male Condor 134 deep in the Grand Canyon. Because of the rugged nesting locations, GPS has been our most valiant tool in monitoring the nesting activity of these two condor pairs. If our estimates based on observation are correct, the unconfirmed egg inside the nest cave of female Condor 126 and male Condor 114 in the Vermilion Cliffs is due to hatch sometime after the first week of June, so keep your fingers crossed and stay tuned for next month’s report…

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