California condors are a rare and unique species that play a big part in America's natural heritage. Today, condors are on the comeback from the brink of extinction. However, these magnificent birds still face threats that impede their survival and recovery.
Threats To California Condor Survival
Primary Threats to California Condors
Lead is the number one cause of death for California condors. While other lead exposure sources may exist (e.g., paint chips), science has clearly shown that condors are primarily exposed to lead by ingesting lead shot or fragments of lead bullets when feeding on carcasses. Lead rifle bullets fragment into hundreds of tiny pieces when they strike an animal and are left behind in the gutpile. When the animal remains are fed upon by condors and other scavengers, ingestion of these lead fragments result in lead poisoning. Many condors have died after ingesting lead in this way and many more have been medically treated for lead toxicity. Zoos that participate in the California Condor Recovery Program are being overwhelmed with lead-poisoned condors from the wild. In fact, nearly every bird in the wild will require emergency treatment for lead poisioning before reaching breeding age.
Hunting, when done with non-lead ammunition, benefits California condors and assists in their recovery by providing additional food sources (unrecovered animals and gut piles). Lead ammunition affects the health of wildlife and humans.
Condors will remain an endangered species until the lead threat is addressed. Reducing and eventually eliminating the use of lead ammunition is an essential step in condor recovery.
"Microtrash" refers to small bits of trash such as broken glass, bottle caps, can tabs, and other smaller, broken down pieces of trash that can be ingested by condors. Condors are curious birds and natural scavengers and are attracted to small bits of trash that stand out from its surroundings. They consistently find and consume micro-trash. Trash cannot be digested.
Additionally, when microtrash is brought to the nest and regurgitated by an adult condor, it is often ingested by condor chicks. The microtrash can get stuck in the gastrointestinal track of young condors and cause impaction, preventing the birds from digesting food, resulting in starvation and death.
The modification of California condor foraging, roosting and nesting habitat has been identified as a threat to the continued recovery of the species. Condors need adequate nesting sites, roosting sites and foraging habitat with adequate food for their basic survival. Human encroachment through land development and disturbance can adversely affect condor behavior, as well as reduce the number of mammals on the landscape, resulting in less food sources for condors. For example, in addition to wild mammals, condors are known to feed on dead livestock such as cows and sheep. Because of this, condors utilize rangelands as foraging habitat. When rangelands are converted to other uses, such as urban development, forage is no longer available for condors.
Wind energy is another type of habitat modification that has the potential to harm condors. As wild condors expand their range, they are coming closer to the increasing number of wind energy facilities in Southern California. These facilities pose a potentially lethal threat to condors from collisions with wind turbine blades.
Powerlines also pose a threat to condors. A number of condors have been killed as a result of collisions with powerlines and electrocution from perching on powerlines or poles. The Service and other California Condor Recovery Program partners participating in captive condor rearing have developed powerline aversion training on condors before releasing them into the wild. The powerline aversion technique has proven successful in reducing the number of deaths from powerlines.
While condors are given power pole aversion training to keep them from landing on poles and becoming electrocuted, chicks fledged in the wild are not exposed to this training. Young newly released or fledged birds who are inexperienced in flight have a greater potential for collision with power lines.
In the past, condor releases were moved to areas with fewer power lines. In addition to power pole aversion training, relocating power lines underground or encasing them in insulated tree wire, which improves visibility to condors, are tools we are using to minimize the potential for collisions and electrocutions.
There are some other factors that pose a lesser threat to condor recovery. These include predation by other animals, poaching, diseases such as West Nile Virus and Avian Influenza, and ingestion of DDE (a breakdown form of the pesticide DDT), found in marine mammals, which contributes to eggshell thinning.