The Fate of Darwin’s “Mischievous” Caracaras

It’s perhaps the most central environmental question facing us: will we be able to adapt to an accelerated pace of climate change?  In the case of birds, the answer would seem to be a resounding “no.”  That, at least, is the impression I get while speaking with experts aboard the Oosterschelde, a tall Dutch sailing ship retracing Darwin’s scientific voyage in the South Atlantic.  We’re on choppy high seas sailing from coastal Patagonia to the Falkland Islands, which lie some 300 miles east of Argentina.  When I’m not clinging to ropes on board out of fear of getting brushed out to sea by gale-force winds, popping pills designed to head off motion sickness, or alternatively attempting to eat my meal in the dining hall without plates flying onto the floor, I’m reflecting on Darwin’s legacy in light of challenges faced by wildlife in this remote part of the world.

From 1832-35, the young naturalist traveled aboard HMS Beagle throughout South America, where he made observations which later informed the theory of evolution.  In the South Atlantic, Darwin noted Magellanic penguins, which had a habit of “throwing its head backwards and making a loud strange noise, very like the braying of an ass.”  The scientist also observed steamer ducks (known locally as logger ducks), equipped with powerful beaks designed to crush shellfish, not to mention wings used purely as paddles.  “These clumsy logger-headed ducks make such a noise and splashing that the effect is exceedingly curious,” the scientist remarked.  He later subjected the animals to a gruesome experiment: “the head is so strong that I have scarcely been able to fracture it with my geological hammer.”

Moreover, Darwin encountered upland geese, which had no instinctive fear of humans.  Such behavior stood in stark contrast to the bird’s demeanor on the mainland, leading Darwin to speculate that animals could change their behavior over time in response to the environment.  From his notebook, it’s clear Darwin first began to consider the concept of island endemism while visiting the Falklands, an idea which he developed much further after visiting the Galápagos.

The scientist also observed striated caracaras, also known as “Johnny rooks”: fearless birds of prey looking like a cross between ravens and eagles, which “were constantly flying on board the vessel …and it was necessary to keep a good look out to prevent the leather being torn from the rigging.”  The Beagle crew grew disenchanted with the birds’ “boldness and rapacity.”  Such comments echoed the views of whalers, who condemned the animals as “flying devils.” “These birds are very mischievous and inquisitive,” noted Darwin.  “They will pick up almost anything … a large black glazed hat was carried nearly a mile.”  In a disparaging tone, the scientist called the birds “false eagles” who “ill become so high a rank.”

“Darwin was responsible for collecting specimens,” remarks Grant Terrell, a young ornithologist on the expedition, “but he also seemed to have an intuition for looking at birds on islands, and considering islands in turn as laboratories for natural selection.”  Running to-and-fro, Terrell provides a frenetic presence on deck while snapping bird photos.  Surveying areas seldom visited on the high seas, he conducts bird counts by first hitting a timer on his phone and later tracking GPS movements.  Over the course of one hour, he takes down the total number of individuals, as well as all the different bird species we encounter.  Afterwards, he uploads data to an online database used by ornithologists, so anyone who’s interested in studying the striated caracara can get information.

Though Darwin would not have denied the environment is changing, he might have been taken aback by the startling rate of climate change which is putting emblematic bird life at risk.  Though the Falklands provide refuge to some of the world’s most important seabirds, it’s unclear whether the islands will continue to be a breeding “hotspot” in a warming world.  Indeed, scientists believe warmer sea surface temperatures could affect the marine food supply.  Terrell says algae forms the bedrock of the ocean marine system and could be adversely affected by acidification.

Further up the food chain, will birds be able to adapt to the alarming pace of climate change?  “No,” he says, remarking “what we are experiencing is not an evolutionary time scale, but something much faster.”  The ornithologist is particularly concerned about birds on islands, which are isolated and hence vulnerable to extinction.  Researchers have grown concerned that as the Southern Ocean continues to warm, Falkland Islands seabird communities could experience drastic turnover or even collapse, which could take place over a mere matter of decades.

As the Oosterschelde makes its way to far-flung islands within the Falklands archipelago, we are careful to decontaminate our shoes in a bucket lying on deck, both before disembarking and later returning to the ship.  It’s a cumbersome process, but necessary as a precaution: though remote wildlife was once regarded as being safe from disease, seabirds are highly mobile, and human activity may help to further spread pathogens between seabird populations.  Recently, avian bird flu circulated in Patagonia, and experts believe spread of the disease is exacerbated by climate change.

As if that were not enough, coastal tussac grasses, which seabirds and striated caracaras rely on for their breeding grounds, have come under strain due to sheep grazing and erosion.  Terrell worries about the fragility of the ecosystem, since insects eat tussac, and birds in turn consume insects.  I wanted to hear more from the ornithologist as we explored isolated Weddell and Saunders Island, to benefit from his expertise.  However, he sprinted ahead of me up barren hillsides while I struggled to catch my breath.  Back on board, Terrell explained, “I don’t find it physically challenging to operate here.  Compared to my field work in Papua New Guinea, this is less intense.  There, I went on expeditions and ate next to nothing.  Here, at least we have a cook and I have a bed to sleep in.”

Turning back to wildlife, he discussed the fate of Magellanic penguins inhabiting the islands.  Summer residents of the Falklands, the animals nest in burrows near the coastline.  With conspicuous black and white bands on their bodies, Magellanic penguins are known locally as Jackass: as Darwin observed, their calls resemble a mournful donkey.  Moderately rapid declines in population have resulted in the species being listed as near threatened.  “Those colonies like flatlands, and are basically at sea level,” Terrell said.  “If you get even a foot or two of sea level rise, penguin populations will become inundated.”

It’s a bleak picture, but I start to rally as we sail into Carcass Island, which displays abundant tussac grass on the coastline.  Striding into the front yard of a lodge, I spot one of Darwin’s “mischievous” striated caracaras.  A charismatic creature, the animal sports a hooked bill and chestnut plumage.  Could the birds be suited to withstand climate change?  Reportedly, striated caracaras are highly intelligent, enjoy solving problems and always want to do something new.  It’s almost as if they’re scientists themselves, walking around and testing their environment.  “I think they’re uniquely bold and curious, and I think that’s something humans can relate to,” says Terrell.

The lodge on Carcass Island

Considering their nature, it would seem striated caracaras should be malleable and adaptable.  And yet, the historic record suggests the animals may be in trouble.  Traveling in the Falklands, Darwin remarked the birds were “exceedingly numerous.”  However, the striated caracara’s population has declined because of human activity like sheep farming, which depleted bird habitat.  Rising sea levels, meanwhile, could threaten habitat even more, as well as the bird’s sources of food.  Though the animal is now protected, its numbers have declined and birds are regarded as near threatened.  Some observers have grown concerned, even suggesting populations of striated caracaras should be transported to urban centers, where they could try to thrive anew.

Disembarking in Port Stanley, I say goodbye to Terrell and the crew and sit down with Mike Jervois, Biodiversity and Protection Advisor for the Falklands Islands.  An Aussie, Jervois remarks that working in the Falklands “isn’t like working in any other place.”  While conducting field work, he frequently encounters the striated caracara.  “If you’re camping near them,” he says, “they’ll wait for you to leave, and then they’ll go through your stuff, or they’ll sneak up on you and one will distract you while the other steals your food.”

Jervois’ tiny team of five or six must handle “absolutely everything,” and therefore rely on drones which can prove useful — as long as it’s not windy.  The devices help tabulate accurate sea bird counts, particularly “because you can’t see everything on the ground if it’s amongst the tall tussac grass.”  Jervois also employs technology like radio trackers, which can be fitted on animals to record their movements, including foraging behavior and migration.  Just what is the environmental outlook for bird populations overall, I ask?  On the one hand, he says, Darwin’s upland goose is faring quite well in terms of numbers.  However, the scientist concedes other birds aren’t doing quite as well.

Jervois outsources some wildlife monitoring to Falklands Conservation, a local NGO.  In a recent report, the outfit warned climate change is the most significant threat to seabirds.  In particular, the organization is concerned about “increased severe weather events; alterations to prey availability as a consequence of warming seas and changes to ocean circulations; increase in infectious diseases; and loss of suitable breeding habitat as a result of drought, erosion or flooding.”  Worryingly, the group remarks that “few of the climate crisis threats to seabirds can simply be avoided,” though resilience could be encouraged through predator removal, habitat improvement and biosecurity protocols.

I’m striding along a pier frequented by sea lions on my way to meet Esther Bertram, CEO of Falklands Conservation.  I spot her sitting in a native plant garden, where we discuss the trials of running a local NGO.  The group owns twenty-three islands and must oversee wildlife with a staff of just thirteen people.  Bertram, who has a background in Antarctic tourism, encourages youth to help volunteer, “but the scale is enormous.”  The islands already exhibit an extreme environment, she remarked, and currently “we’re at the stage where we just need any native habitat to grow.”

When I asked if she was concerned about the plight of specific types of vegetation, she answered, “all of it.”  Falklands ecology has shifted massively since Darwin’s day, with only a tiny fraction of tussac habitat remaining.  Unfortunately, however, replanting tussac was a massive logistical challenge.   Walking back to my peculiar American-style motel, I muse on Darwin’s legacy.  Over time, unique bird life evolved in the Falklands, but what if the islands become unsuitable for those very species due to climate change and the archipelago can no longer offer a bastion for the likes of the striated caracara?

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