Condors and Trash
Yes, condors, like other animals such as albatross, have been known to eat trash. In fact, trash ingestion was found to be the leading cause of death for wild condor nestlings in a study published in 2012 (Rideout et al., Journal of Wildlife Diseases). Why condors ingest trash is unknown, but condor biologists think nestlings are exposed to trash items that have been brought back to the nesting area intentionally by their parents. (If you are interested to learn more about this topic, look up this paper “Why do condors and vultures eat junk: The implications for conservation” by Houston D, Mee A, McGrady M. published in the Journal of Raptor Research volume 41, pages 235-238 2007.)
We have seen condor nestlings ingest items such as coins, bottle caps and even a light bulb filament!
In addition to digestive impaction, trash ingestion may have toxicological effects on condors. Zinc toxicosis associated with trash ingestion was determined to be the cause of death for one condor nestling, and in two other cases nestlings that died of trash ingestion had elevated liver copper concentrations.
Condors are routinely lead poisoned by ingesting lead fragments in carcasses shot with lead-based ammunition, but it has been less clear whether trash ingestion represented another source of lead poisoning. To address this question, some of our science team members and condor collaborators recently published a paper entitled: “Lead Exposure Risk from Trash Ingestion by the Endangered California Condor (Gymnogyps californianus)” in the Journal of Wildlife Diseases. Because ingested or potentially ingested trash accumulates in nest areas, we sampled items found in the vicinity of nests or removed from nestlings.
We found that the majority of lead-containing trash items were ammunition-related. Out of 1,413 trash items collected from condor nest areas and nestlings in the Transverse Range of Ventura County, California USA, between 2002–2008, 27 items were found to have lead concentrations of potential toxicological concern. Twenty-two of these 27 items were clearly ammunition-related (shotgun shell, casing, etc., see photos below) and only three of these items were clearly not ammunition-related (two items un-classifiable). Our results suggested that trash ingestion of non-ammunition items does not pose a significant lead exposure risk to the California condor population in California, but ingestion of ammunition-related trash could be of concern and efforts to minimize a condor’s exposure to ammunition-related trash are warranted.
Here are some representative photos of the lead containing items we found either in condor nest areas or nestlings (from the Supplement section of our published paper):
Metal items were categorized as ammunition-related if they were clearly identifiable as such with corroboration by a California Department of Fish and Wildlife Lieutenant and a retired Assistant Chief with a combined 48 years of experience in law enforcement (J. Nores, C. Babich). Items with a leachate lead concentration >1 µg/mL were classified as containing sufficient lead to be of potential toxicological concern and referred to as ‘lead-containing’.
And just because we can’t have a blog post without a condor photo, here is one of condor 107 (red7), proudly strutting his stuff in an area free of trash!