For over 2,000 years, Andean condors have been nesting — and pooping — in the identical cliffside grotto excessive within the Andes. This gargantuan pile of guano is now offering an unprecedented peek deep into the birds’ previous, revealing a stunning constancy to elevating chicks there even because the area modified dramatically.
Analyses of the deposit present that the condors overhauled their food regimen after European colonization of the Americas. The birds additionally virtually deserted the location for a millennium, probably because of centuries of erupting volcanoes, researchers report Might 3 in Proceedings of the Royal Society B.
“A fabric that would simply be ignored or discarded as waste can really educate us fairly a bit about how populations, communities and ecosystems reply to environmental change,” says Rachel Reid, a paleoecologist at Virginia Tech in Blacksburg who was not concerned within the analysis.
With a wingspan of over three meters and the heft of a toddler, Andean condors (Vultur gryphus) are the biggest birds of prey. Present in South America’s Andes Mountains and alongside the western shoreline of the continent, the condors are additionally threatened with extinction. Solely about 10,000 birds stay, and their numbers are declining.
Efforts to guard them hinge on understanding their habits and ecology. However learning Andean condors might be difficult: The birds spend most of their time on the wing in distant mountain areas, which makes them troublesome to seize and monitor, says paleoecologist Matthew Duda of Queen’s College in Kingston, Canada.
However in 2014, Duda’s colleagues discovered a condor nest in Argentina’s Nahuel Huapi Nationwide Park, tucked in a cliffside nook that turned out to be a ripe supply of data. Researchers hiked an hour from the closest street and rappelled 10 meters down alongside the cliff simply to succeed in the nest. Not like most condor nest websites, this one was sheltered from rain and snow. As a substitute of washing away, the droppings of successive breeding pairs constructed up layer upon layer, making a dense, pale mound.
Data within the preserved poo offered the “good alternative for us to return in time,” Duda says.
The researchers carved a 25-centimeter-deep slice out of the guano pile. DNA and ratios of particular chemical substances within the poop hinted at what the condors ate over time. Different chemical substances akin to sulfur and potassium in addition to preserved algae revealed altering environmental circumstances.
Chemical relationship of the samples divulged that the oldest layers within the deposit had been not less than 2,200 years outdated. That the condors had been utilizing this nest location for thus lengthy was “extraordinarily stunning,” Duda says. Most species of birds return to the identical space to boost younger, however hardly ever the very same nest, if ever. “If they’ve been utilizing the identical nest and preserve coming again over and time and again, it implies that the place these birds are nesting is a brilliant necessary a part of their ecology and their habits,” he says.
The speed at which feces gathered slowed drastically from 1,650 to 650 years in the past, dropping from 0.08 cm per yr to 0.003 cm per yr. That slowdown suggests condors largely left the location for a millennium, the researchers say. Across the identical time, close by volcanoes went by means of a volley of eruptions. Heavy ash that might have blanketed the area’s vegetation may have prompted herbivores to maneuver away, lowering the provision of carcasses for the condors to feed on, Duda and colleagues suspect. The birds could have glided away to scavenge in greener pastures and returned to the realm after the volcanic paroxysms ceased.
Related connections between eruptions and declines in chook populations have beforehand been documented in guano data, says Dulcinea Groff, a paleoecologist on the College of Wyoming in Laramie who was not concerned within the new work. As an example, historic excrement has linked dips in Gentoo penguin populations to volcanic strife (SN: 4/12/17).
The condor guano additionally reveals a serious food regimen shift, Duda and colleagues say. Previous to European colonization of South America, the birds primarily scavenged the carcasses of beached whales and a few native mammals like llamas and guanacos. However in current centuries, livestock like sheep and cattle have made up the majority of their food regimen.
And in contrast to fashionable condors, those who lived many centuries in the past didn’t have elevated lead and mercury ranges of their our bodies. The poisonous metals can accumulate in scavengers that eat carcasses shot with lead ammunition (SN: 6/26/12). Scavengers excrete among the metals of their droppings, which might then be detected by scientists. The discovering helps affirm that heavy metallic contamination is a current phenomenon.
The analysis “provides us a for much longer timeline to know what the pure variability is in a inhabitants,” Duda says. Since this research is a snapshot of only one nest, he and colleagues plan on collaborating with different researchers to seek out comparable condor nests to see whether or not the identical patterns written in guano emerge.
Within the meantime, the condors’ obvious loyalty to this very particular nest website — even doubtlessly by means of centuries of volcanic mayhem — highlights simply how essential the preservation of such websites could also be for his or her profitable conservation, Duda says.