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Interference between Individual Condors

Individual condors of the same species may also fight with and displace each other.  In northern Patagonia, Donázar et al. (1999) studied Andean Condors at carcasses and found a dominance hierarchy based on size, sex and age.  Male condors, which weighed 36-37% more than females, dominated female condors independent of age. In addition, within each sex group, older birds dominated younger birds.  Thus, adult male condors occupied the top of the dominance hierarchy, while juvenile females occupied the bottom. 

Because males and older females displaced juvenile females at carcasses, juvenile females tended to avoid foraging in the mountains where food was more abundant and encounters with males and older females more likely.  Instead, they foraged more often over the plains where they were less likely to find food, but where they were more likely to avoid encounters with males and older females once they found food.  Males and adult females preferred to forage in the food-rich mountains.

In northern Peru, Wallace and Temple (1987) reported slightly different results.  They found that while male Andean Condors generally displaced female condors of the same age at carcasses, individual females sometimes displaced individual males that were more than one year younger.

Why Condors are Endangered

Condors are less abundant today than in the beginning of the nineteenth century because so many have been shot and poisoned by humans.  Collisions with overhead electrical power lines also cause many condor deaths.

Poisoning comes mainly from two sources (1) lead ammunition in the carrion of animals killed with firearms, and (2) poisons set out to kill predators such as coyotes, wolves, pumas, bears.

When condors eat animals that hunters shoot with lead bullets or lead shot, they often ingest the spent lead along with the meat.  Over time, the amount of lead in the condors' bodies increases because these birds have no natural mechanisms for removing lead from their bodies.  Eventually, the lead concentrations become so high that the condors die.  (Pattee et al. 1990; Meretsky et al. 2000, 2001; Snyder and Snyder 2000; Church et al. 2006; Finkelstein et al. 2010). 

During 1980's, California Condors died so frequently from lead poisoning that the government captured the last remaining individuals for captive breeding, because it could see no practical way to protect the condors from this poisoning (Bessinger 2002).  Starting in the 1990's and continuing through the present, some of the captured condors and their captive-bred young were released back into the wild, with the hope that they will establish new, viable populations. 

Unfortunately, because ammunition containing lead continued to be sold and used by hunters in areas where condors are released, wild condors soon began dying once again at very high rates from lead poisoning.  Meretsky et al. (2001) concluded that the current death rates were so high that they approached the "disastrous mortality rates" of the 1980's and so were unsustainable.

Fortunately, a technological solution for this problem is now available: Ammunition made of non-toxic substances, like TTB (tin, tungsten, bismuth) composites.  Use of such lead-free ammunition can prevent poisoning not only of condors, but of many other animals as well, including waterfowl which often ingest lead shot while foraging in wetlands (Sanderson & Bellrose 1986).  Phasing out lead in ammunition, as was done for lead in paint and gasoline, would therefore be an important step in the conservation of wildlife in general (Beissinger 2002).  An added advantage is that, because of new manufacturing innovations, lead-free bullets have superior ballistics to lead bullets (Cade 2007).

Consequently, in 2008, California banned the use of lead ammunition for most hunting within the range of the condor in that state.  Studies show that hunter compliance with this new law has successfully decreased lead poisoning.  For example, a comparison of lead concentrations in the blood of Golden Eagles and Turkey Vultures before and after implementation of the ban on lead ammunition, found that blood lead concentrations declined dramatically within a year of the ban's implementation (Kelly et al. 2011).

Sadly, however, lead ammunition continues to be used by hunters in other states within the range of the California Condor, and lead poisoning there continues to be the major cause of death among adult condors (Gree et al 2008). 

In addition, a group of South American researchers has recently found elevated levels of lead in Andean Condors, suggesting that this bird, like the California Condor, is also ingesting spent lead bullet fragments and shotgun pellets from carrion (Lambertucci 2011).  Although the levels of lead found are not yet as high as those attained by the California Condor, these researchers nevertheless recommend the prohibition of lead ammunition in the range of the Andean Condor and its replacement with non-toxic ammunition, as a preventive measure to protect this bird and other wildlife from lead poisoning.

Another major source of condor mortality is shooting (Snyder & Snyder 2000).  There are always a few egomaniacs who will shoot down giant birds like condors to try to prove their masculinity or simply to see "what the heck that big bird is" (McMillan 1968; Snyder & Snyder 2000).

Although many activities of hunters are detrimental to condors, it is wrong to conclude that hunters and condors are necessarily incompatible.  In some circumstances, hunting could benefit condors.

For example, if hunters did not shoot at condors, if they used lead-free ammunition to kill game, and left part of their kills for condors to eat, they could help condors by providing more food for them (Snyder & Snyder 2000).  Such "responsible" hunters might even be important to condors in areas where large predators have been extirpated, because these predators formerly left carrion for condors to eat.

Unfortunately, because every population of hunters has a few bad individuals, and it only takes a few of these to endanger a whole population of condors, hunting in condor country must be carefully monitored by competent, well-equipped police forces and all laws strictly enforced.  McMillan (1968) provides disturbing accounts of what happens when irresponsible people are allowed to hunt unsupervised in condor country.

In southern California, ingestion of junk by nestling condors is the primary cause of nest failure and is preventing re-establishment of a viable breeding population (Mee et al. 2007).  Of nine nestlings hatched in the wild between 2002 and 2005, four died and two ill nestlings were removed from the wild because their parents had fed them many small man-made objects made of metal, glass and plastic.  Adult condors seem to have no trouble regurgitating such junk, so it is unknown why nestlings can not do so.

The restoration of condor populations is also threatened by an additional problem:  the unnatural and naive behavior of young, captive-reared condors.  These overly-tame birds have never been taught by their parents how to survive in the real world outside the zoos where they were raised, and consequently, when they are released into the wild, some approach humans without fear (Snyder & Snyder 2000; Meretsky et al. 2001; Beissinger 2002).

References

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Information about this Review

This review is also available in the following languages:  

Portuguese    Spanish

The author is:  Dr. Paul D. Haemig (PhD in Animal Ecology)

Photograph at top of page:  Adult California Condor soaring over the Grand Canyon, Arizona.  Photo by Kurt Vile (USA).

The proper citation is:

Haemig PD  2012    Ecology of Condors. ECOLOGY.INFO 25.

If you are aware of any important scientific publications about the Andean Condor or California Condor that were omitted from this review, or have other suggestions for improving it, please contact the author at the following e-mail address: 

director {at} ecology.info 

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