The discovery of a 2,200-year-old Andean condor guano deposit may demonstrate how species have or haven't adapted to the natural and human causes of environmental change over the course of time.
That's according to John Smol, a biology professor at Queen’s University, who spoke to The Weather Network earlier this year about the finding that was detailed in a study published in May 2023.
The examination documents the finding of a doughnut-shaped deposit of condor guano in Patagonia, Argentina. Researchers uncovered a millennia-scale record of the animal's behaviour and diet, also putting a spotlight on the region’s historical records of volcanic and human impacts on this particular at-risk species.
"When we finally did all the data, it [came] out at about 2,200 years of accumulation, which in itself was quite an important part of history," said Smol. “We really had an interesting history of a lot of things happening in Argentina.”
Dry climate and overhanging rock ledge helped preserve it
The condor nest site and guano deposit used in the study is situated within Nahuel Huapi National Park. The study notes that the dry climate and the overhanging rock ledge are what led to the preservation of the site and its guano deposit for at least 2,200 years.
"We often think about climate change and pollution, but there was the European expansion or conques and different volcanic eruptions. This is a very volcanic area. A lot of that history was actually contained in this guano deposit," said Smol.
Andean condors will typically nest in areas that are protected from the elements and predators. These include under rock overhangs and shallow caves on cliff faces, the study noted.
Suitable nesting sites are finite, so condors will often reuse them from generation to generation, as long as local environmental conditions will aid breeding activity.
Diet full of contaminants, then changed from human impact
Researchers were able to determine that the well-conserved, ancient DNA, stable isotopes, metals, and organic compounds such as cholesterol also offered an account of condor diet exposure to contaminants during the 2,200-year history of the deposit.
One thing that might make a condor "especially susceptible" to lead pollution is they do eat animals that were killed by hunters, and often that includes the toxic-composed shot, Smol said.
"When you're eating a dead organism that may have been left behind, they're probably ingesting the lead shot, as well, [which] may be increasing their lead," said Smol. "We had a history of diet, we had a history of occupation, and we had a history of pollution."
According to a news release, the data collected showed a distinct modification to the diet, attributable to landscape-scale human impact.
Following European colonization approximately 150 years ago, condors had to switch diets after humans had a noticeable impact on the landscape and food sources, resulting in a reliance on ranched livestock instead of native fauna.
Smol 'cautious' about how far back deposit can trace environmental changes
The study's author noted that understanding how animals respond to large-scale environmental changes is difficult to achieve because monitoring data are rarely available for more than the past few decades.
Lacking long-term data is "one of the biggest challenges we have" in ecology and environmental science, Smol said.
"We don't have the long-term data. No one was measuring condors 1,000 years ago. These are sort of indirect ways, but they provide a lot of clues as to what's happened in the past," said Smol.
Smol cautioned about using a single deposit to determine how animals have adapted to environmental changes over hundreds or thousands of years.
“We don't want to extrapolate too much until we see maybe 10 deposits or at least five deposits. I'd be a little hesitant to go too far behind that," said Smol. “We provide hints of how they've changed over time.”
However, he noted that scientists can provide "an idea" of how long the Andean condor has been here.
"We can show that, in fact, they were here at least 2,200 years ago [and] then they declined for about 1,000. Those are important population trends for ecologists, ornithologists and ecosystem managers," said Smol. "We can show the past, which is what we try and gauge the future with."
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Thumbnail courtesy of Chris Grooms/Submitted.
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