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First Condor Egg Laid This Year on Big Sur Coast Found Crushed
Big Sur, California – Biologists with Ventana Wildlife Society's Condor Restoration Program discovered the crushed remains of a thin-shelled condor egg during a routine nest check on Thursday, February 27. The field team gave the condor pair a fake egg, made to look and feel exactly like the real one, in hopes that they continue caring for the egg long enough to bring back an egg from captivity to hatch in the wild. Female condor #222 laid the thin-shelled egg and, unfortunately, had already abandoned the nest before biologists were able to provide the fake egg.
Last year, female condor #171, laid an egg that was immediately crushed due to eggshell thinning but biologists at that time were able to give the fake egg in time (see photos provided). Biologists then returned with an egg in the process of hatching two months later and swapped out the fake egg so that the condor pair could raise a chick, which was successful. Unfortunately, condor #222 has only one more chance to reproduce this year but only if she lays another egg, called replacement clutching.
Eggshell thinning was first documented by a team of scientists led by Joe Burnett of Ventana Wildlife Society and published in the journal The Condor last year. As it turns out, many of the coastal dwelling female condors, as is the case for this one, lay thin-shelled eggs, which is most likely a result of exposure to DDE, a harmful breakdown chemical of DDT found in the marine food web. Condors regularly scavenge on the carcasses of Sea Lions, which can harbor dangerous levels of DDE and other marine contaminants. "We found that condor eggshells in Big Sur averaged 34% thinner than eggshells from the inland population in southern California", said Joe Burnett.
Eggshell thinning is a significant problem but one that is going away without the need for additional regulations. In a majority of cases, eggshell thinning has led to failure, resulting in lower than normal hatching success, a level too low to sustain the population. Researchers remain optimistic despite the recent failures because data strongly suggests that DDE levels are slowly dropping in the California marine food web. Furthermore, biologists are confident in the techniques used to help breeding pairs with their egg problems until eggshells return to normal.
The Society's Executive Director, Kelly Sorenson said, "the coast is critically important to wild condors because of low lead exposure from spent ammunition. What's most important from a recovery standpoint is for condors to survive year after year and in time their eggs will return to normal." "The problems condors face associated with lead poisoning far outweighs the problems we're seeing of thin-shelled eggs on the coast", said Joe Burnett.
PHOTOS AVAILABLE include condor #171 (last year) with crushed eggshell in foreground and the same condor in the same nest two months later accepting a captive-laid egg about to hatch in the wild.
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