Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study confirms ammunition as main source of lead poisoning in condors

01.09.2006
A study led by environmental toxicologists at the University of California, Santa Cruz, has confirmed what wildlife biologists have long suspected: Bullet fragments and shotgun pellets in the carcasses of animals killed by hunters are the principal sources of lead poisoning in California condors that have been reintroduced to the wild.

Lead poisoning is a major factor limiting the success of efforts to rebuild populations of the endangered California condor. Since the mid-1980s, condors have been bred in captivity and released back into the wild in California, Arizona, and Baja California. The birds, which feed on carrion, can ingest lead from ammunition in animal carcasses or gut piles left behind by hunters.

The UCSC researchers used a "fingerprinting" technique based on the unique isotope ratios found in different sources of lead. The technique enabled them to match the lead in blood samples from condors to the lead in ammunition. Their findings were published online today by the journal Environmental Science & Technology.

"There had been anecdotal reports for years about condors being exposed to lead from ammunition, but there was never enough clear evidence to document the extent of the problem. We knew that we could probably identify the sources of the lead using isotopic signatures," said Donald Smith, professor and chair of environmental toxicology at UCSC and a coauthor of the paper.

The study was spearheaded by Smith's graduate student, Molly Church, who is now at the University of Pennsylvania's School of Veterinary Medicine and is first author of the paper. Church worked with researchers at several institutions and organizations, including the Ventana Wildlife Society and the U.S. Fish and Wildlife Service, to collect and analyze blood and tissue samples from California condors. She also analyzed ammunition obtained from a variety of sources throughout central California.

"We sampled the ammunition that these birds are most likely to encounter in the remains of hunted game, and we found that lead from those sources can account for the lead in the blood of 77 percent of the birds tested," said Church, who undertook the study after spending a summer monitoring condors as a volunteer with the Ventana Wildlife Society.

The researchers obtained blood samples from 18 free-flying condors in central California and 8 birds that had been raised in captivity and were still in holding pens waiting to be released. At the time of the study, this sample represented 43 percent of the wild condor population in all of California.

The lead levels in the blood of prerelease condors were low, and the lead was isotopically similar to background lead in the California environment. In the free-flying condors, however, blood lead levels were higher and the lead had a different isotopic composition that approached the composition of the lead in ammunition. In the most severely lead-poisoned birds, the blood lead matched exactly the composition of the lead in ammunition, Smith said.

"We found that in the birds with elevated blood lead, the lead isotope ratios fit a mixing model in which one source of lead is the background environment and the other source is ammunition. The results show that lead ammunition in animals shot and left in the field is the predominant source of lead exposure in condors," he said.

Kelly Sorenson, executive director of the Ventana Wildlife Society, said the study provides a solid basis for efforts to resolve the problem of lead exposure in condors. Possible solutions range from legislation limiting the use of lead ammunition to voluntary programs to encourage the use of alternative ammunition in areas where condors are known to scavenge for food, he said.

"There are different ways to get at this problem, but no matter how it is resolved in California, this research was desperately needed not only to confirm the source of the lead but to demonstrate the extent to which ammunition is contributing to the problem," Sorenson said.

In another part of the study, the researchers showed that feathers can be used to monitor lead exposure in condors. They analyzed lead in tissue samples and a feather from a condor that had died of lead poisoning in Arizona. They found that the feather, sampled sequentially along its length, provided a record of the bird's history of lead exposure.

"This shows that we can use feathers to look at the history of lead exposure in individual condors, and we're just starting to do that now with birds that have been reintroduced in California," Smith said.

The elevated lead levels in reintroduced condors are cause for concern even when they are below the level that would cause death from acute lead poisoning, he added. Although it is very difficult to evaluate sublethal effects of toxic substances in wild animals, he said, lead is well known to cause neurological problems in vertebrate animals at relatively low levels of exposure.

"The lead levels that we commonly see in condors are well above the levels considered a concern for human health. If we saw those levels in children, they'd be diagnosed as lead-poisoned and medically treated," Smith said.

Church said she hopes the findings prompt greater efforts not only to reduce lead exposure in condors but to reduce lead contamination in California in general.

"Lead is a well-known toxin that should no longer be getting into the environment, and it would truly be a shame if lead poisoning negated the significant condor conservation efforts and achievements that have taken place over the past several decades," she said.

Tim Stephens | EurekAlert!
Further information:
http://www.ucsc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>