Patagonia and the Web of Life

Patagonia feels like the end of the earth. The region comprises the southern tip of South America, of both Argentina and Chile. Its southern most islands extend further south than Africa's Cape Agulhas or New Zealand's Stewart Island, often serving as base to launch expeditions into Antarctica. The conditions are frigid, the weather subpolar. Without any major landmass to inhibit its flow, the airstream rips around the south pole unimpeded, where wind here often exceeds 100km/h.

The Spanish attempted to start a colony here, twice. Both ended in famine. Coming from the Mediterranean, they had little experience living in this kind of environment. As colonists, they were most dominant around equatorial climates, like what they found surrounding the Gulf of Mexico. Eventually in 1848 Chile's independent government established Punta Arenas as a penal colony. This was a way for them to claim control of the strategically important region. The grueling winds would have been a harsh punishment for prisoners there. It wasn't until sheep farming and then gold mining booms after the 1890s that the region began to attract immigrants, mostly from Russia and Croatia.

The rich diversity of wildlife that these European migrants saw in this expansive new landscape was unlike any they had encountered. Tens of thousands of guanacos and rheas roamed the grasslands, with burrowing armadillos and Patagonian maras, hunted by South American false foxes and mountain lions, while gigantic condors circled the skies above. The harsh climate here may have been partly what made this one of the last refuges for South America's remaining native megafauna. For a brief period, the density of these species was likely even greater than it was in pre-colonial times, before the demographic collapse of the indigenous population who once subsisted upon these animals (Mann, 2005).

This growing European population brought with it a number of new ecological challenges, most notably increased hunting with firearms, the introduction of livestock, and other invasive species. Throughout South America, the population and range of these native species collapsed to a fraction of their prior historic levels. Many became regionally extinct in more northern latitudes. But within recent decades there's been a growing recognition of our impact, and a groundswell of support for preserving habitat. The national parks of Patagonia are now becoming rare environmental success stories, providing refuges where these once-threatened species are beginning to bounce back, while offering some of the most epic wildlife viewing opportunities within the Americas.

Sections

• King Penguins of Tierra Del Fuego
• Geography & Geology
• Guanacos & their Domesticated Descendants
• The Puzzling Evolution of Rheas
• Mountain Lions of Torres Del Paine
• Andean Condors
• The Web of Life
• Sources

King Penguins of Tierra Del Fuego

My original plan was to take a ferry from Punta Arenas across to Isla Tierra Del Fuego, but I managed to pick the one day this month the ferry didn't run. A four-hour detour got me to another ferry to the north. The scale of the landscape here is massive. It's desolate. No service stations either. The car rental gave me an emergency gas tank just in case.

The ferry travels across the Strait of Magellan, named after the Portuguese explorer who mapped the region during the first circumnavigation of the globe (Pigafetta, 1969). The expedition had been commissioned by the Spanish King Charles I. It began with a fleet of five ships. Three years later, only one ship returned, with Magellan himself having been killed by natives of the Philippines. The expedition did however provide a route for the Spanish to reach the west coast of the Americas. The Magellan passage avoided the treacherous open ocean to the south, between Cape Horn and the Antarctic Peninsula. This region is named Magallanes in his honor, as are the Magellanic Penguins that live here.

I'm here to see a different species though, the King Penguin, at the aptly named Parque Pingüino Rey. It's the only spot outside of a couple of remote subpolar islands where they still live, so I didn't want to pass up the opportunity. The colony here was only re-established in 2010, after their numbers collapsed here due to excessive hunting in the 19th century (Pütz et al., 2021). This population now spends the year primarily hunting the waters of the Strait of Magellan.

The colony is smaller this time of year, about 80 birds. So as to not disturb them, the penguins are only viewable from behind a wooden hide. Some of the juvenile chicks are beginning to molt. It can take the chicks 10-13 months to fledge, until which time they're dependent upon their parents for food. They huddle together to block the cold. Every few minutes those getting hit by the wind move to the sheltered side of the mob. Before too long the newly exposed would start to get cold and it would be their turn to move, in a slow-motion waddling cycle.

Geography & Geology

Making my way north, I travel through Puerto Natales to Torres Del Paine. Snow covered cliffs of the Andes slowly rise from the horizon. At the heart of the park are the geological formations of Los Cuernos (the horns) and Los Torres (the towers). These were formed by gigantic magma plumes rising under the earth roughly 12 million years ago (Leuthold et al., 2012). Over eons it uplifted through tectonic action and became exposed. The subpolar climate then deposited a recurring cycle of glaciers. At its peak a 1.2 million years ago ice fields covered almost the entire southern portion of Patagonia (Mercer, 1976). The grinding action of these glaciers scooped and polished the rock, carving out the region's many fjords and turquoise lakes, now inland channels weaving across to the southern Andes. The glaciers here still comprise the world's second largest ice field outside of Antarctica, although now the ice is now receding at an accelerating rate. The rate of ice loss at Patagonia's Glacier Viedma has tripled in recent years (Lo Vecchio & Lenzano 2018).

To the east of these icy peaks is an ecosystem entirely distinct from Chile's wet southwest. The Southern Andes create a rain shadow in Patagonia, similar to how California's Sierra Nevada and the Pacific Northwest's Cascades creates the deserts and dry grassland to their east. As prevailing westerly winds push air up the mountains, it cools and compresses, squeezing out the moisture. Grasses and low laying scrub thrive on these cool, dry plains. These grassland form the foundation of the Patagonian food chain, supporting a wide array of grazers and foraging species.

Guanacos & their Domesticated Descendants

Herds of guanacos are scattered across the Patagonian steppe. They're the wild ancestor species of domesticated llamas. Similarly, alpacas are the primarily domesticated descendants of vicuñas, a smaller relative species of the guanaco, that have been crossbred with llamas/guanacos (Kadwell et al., 2001). These species all stem from the Camelid family, which include Camels. People tend to associate camels with Mongolia or the Middle East, but the fossil record indicates that camels actually first evolved in North America. They traveled west through Asia across the Bering land bridge before going extinct in the Americas (Rybczynski et al., 2013). Wild camelids are now extinct in North America, and camels themselves are no longer native anywhere within the New World. The evolution and domestication of guanacos and vicuñas, however, has been fundamental in the shaping of South American history, becoming the most important animals of Andean civilization.

The domestication of guanacos was a slow process. The transition from hunting to herding and then to full domestication took thousands of years. The first osteological evidence of herding dates to 7100 BP, when they became heavier and stockier (Hugo, 2021). Within archeological excavations during this period, remains of guanacos also started to increase in frequency relative to the bones of deer (Stahl, 2008). They were becoming a higher ratio of people's diets relative to other wild animals. Evidence of guanaco bone pathologies became common around 4900-4700 cal. BP, a consequence of disease spreading through denser, confined populations. The earliest discovered corals date to 4635-4232 BP. This is when signs of domestication began to accelerate. This process may have occurred during this period in multiple locations simultaneously, such as northern Argentina and Puna de Junín of Peru (Hugo, 2021; Stahl, 2008).

By the Early Horizon Period, from 900 BCE, llamas had become common throughout the central and southern Andes. They were used as pack animals, consumed for meat, sheared for their wool, with their dung used for fuel. Their growing importance in later centuries can be seen with them being buried alongside of deceased Moche lords, to accompany them in the afterlife. By the time of the Inca, they were being used as part of massive trade networks. Caravans hundreds of llamas long hauled goods throughout their empire.

Guanacos were still prolific throughout the Peruvian highlands during this period too. The Inca had their own protected game reserves that were off-limits to unauthorized hunting. Guanacos & vicuña were seen as a manifestation of their Apus, or mountain Gods. These wild herds were periodically harvested with organized hunts comprised of tens of thousands of men (León, 1520-1554). They would first drive them down from the scattered peaks, then the hunters would form giant circles with joined hands, ever tightening to pen them in. Some of their meat would be dried and kept in their store houses to help feed their army. The Inca also led hunting drives targeting predators, killing mountain lions and spectacle bears, so as to protect their herds.

During the colonial period guanaco and vicuña populations began to crash. Cieza de Leon, an early Spanish chronicler, notes that the conquistadors had almost exterminated them. The Andes are thought to have once sustained populations of 30-40 million, but by the 19th century, due to overhunting by humans and overgrazing by livestock, their numbers had dropped to roughly seven million. By the 2000s both guanacos and vicuña were nearly extinct within Peru, where the wider Andean guanaco population dropped to roughly half a million animals. Today their range is 40% of what it once was (Burgi et al., 2012). The national parks and wildlife preserves of Patagonia are some of the few places you can still see large herds of Guanacos. Here they play a critical role as a keystone species within food chain. Both mountain lions and Andean condors depend upon them here as their primary source of food.

The guanaco are intelligent sociable animals, displaying traits like play and flirting. Like other ungulates (deer, goats, sheep, elk, etc), they typically roam in groups of either bachelor males or a single mature male with a harem of females. As juveniles go through puberty, they are driven out from the herd by the dominant male. I witnessed this, with the larger male chasing the younger, biting at its hind legs and groin from behind, in what can sometimes result in castration. The mother then challenged the alpha, getting between them and angrily spitting at it. This biting trait is still found in domesticated llamas, leading their owners to pull the sharp canine "fighting teeth" of males (Cebra et al., 2013). As harsh as this behavior is, it's evident how those who had this tendency, driving other males from herds, would be more likely to amplify that trait into the gene pool of future generations. By denying competitor males the opportunity to mate, those individuals who exhibited this tendency were rewarded in terms of higher frequency of reproduction, eventually becoming a common characteristic of the entire population. This kind of aggressive behavior though only tends to become dominant in those patriarchal pack animals where the young don't require much support from the male to reach maturity. Newborns can begin to walk and graze shortly after birth. In contrast, the many upland geese on the plains are almost always found in monogamous pairs, since the eggs require an attentive father to help with incubation. Each species has their own unique set of constraints.

The Puzzling Evolution of Rheas

Another emblematic Patagonian species is the Darwin rhea or lesser rhea, locally known as Ñandú. These huge flightless birds can frequently be seen grazing throughout Patagonia's vast grasslands, foraging through vegetation with their elongated necks. They play an important role in seed dispersal. Although they're mostly herbivorous, they'll also eat insects, and small reptiles and rodents.

This species of rheas was named in recognition of Charles Darwin. He documented the bird during his time as a young naturalist, while on his five-year voyage aboard the HMS Beagle. The ship later took him around Cape Horn to Galapagos, a journey that would provide the insights to write Origin of the Species. Further north in Argentinian Patagonia, the towering Mount Fitz Roy was named after the captain of that same historic voyage.

The evolution of these birds still poses something of an enigma. They resemble a number of other giant, flightless Ratite bird species from throughout the Southern Hemisphere, such as Australia emus, African ostriches, extinct Madagascan elephant birds, and extinct New Zealand moas. Since each of these landmasses were once part of the Gondwana super continent, it was long assumed that they descended from another giant flightless ancestor. Gondwana began to break apart in the late Cretaceous period, roughly 100 million years ago, and South America finally broke away from the Antarctica land bridge around 50 million years ago (Reguero et al., 2014; Van den Ende et al., 2016). With this increasing geographic isolation, the regional populations were thought to have then diverged into distinct species.

A 2014 DNA study challenged this understanding of their evolutionary history (Mitchell et al., 2014). This team determined that Madagascar elephant birds were most closely related to New Zealand kiwis, and most distant from ostriches. This is unexpected because Africa and Madagascar split from these other landmasses the earliest. They instead propose that some of these ratites may have descended from a smaller flying ancestor, which then evolved into the giant flightless birds independently, after these land masses had already broken apart. If so, they may have been filling the ecological herbivory niche left following the extinction of non-avian dinosaurs 65 million years ago. This would be an example of convergent evolution, where a similar morphology arose independently due to similar environmental pressures.

Today rhea numbers are a fraction of what they once were. Since pre-Columbian times they had been hunted for their meat and feathers. Both indigenous people and later European-descendent Gauchos caught them with bolas, three balls connected by a rope thrown at their feet to immobilize them (guanacos and vicuna were similarly hunted with these). In more recent centuries, over-hunting with guns, increased fencing, and overgrazing of livestock led to a population collapse throughout much of South America. But fortunately, due to conversation efforts and increased protected habitat, their population is now relatively stable in southern Patagonia, and they are being re-introduced in some wildlife preserves where they had once become regionally extinct (Tompkins Conservation, 2021).

Mountain Lions of Torres Del Paine

Feeding upon these species is Patagonia's apex predator. It is known by many names, most commonly puma, cougar or mountain lion. Despite that latter name, it's more closely related to the common house cat and lynxes than to lions or other big cats. They're mostly solitary, stealthy, ambush predators, and adaptable generalists. Their range spans almost the entire latitudes of the Americas, through tundra, deserts, and jungle, preying upon everything from insects and lizards to porcupines and sea lions. Here though their main source of food is the Guanaco.

I travelled here with high hopes of finally seeing pumas in the wild. While they are occasionally seen in many regions I've explored in North America, their numbers are far lower, partly due to less prey. With Torres Del Paine's large herds of guanaco, this is likely the highest density population from their entire cross continental range. The cats are bigger here too, adapted for the large game. I chatted with a ranger to asks if there had been any recent sighting in the area. He directed me to a nearby valley where they frequented. Regarding safety, cougar attacks on humans are exceedingly rare, where only one fatal attack on a human has ever occurred within the national park. Nonetheless, he still advised that I restrict my hiking to the middle of the day, as they tend to be on the prowl near twilight.

As I began down the trail, it quickly became apparent that they had recently been here. Guanaco bones littered the landscape. Some of the kills were still fresh. A single kill will sustain a puma for a week or two. They'll drag the carcass off to somewhere hidden and cover it with branches to protect it from carrion birds, like the massive Andean condor soaring overhead. As I continued through the valley up to a rocky outcropping, I came across some rock art. While open to interpretation, the scene seemed to depict an ancient human with two elongated creatures resembling these cats. Was this a hunter trying to communicate to those later traveling through, to be wary, that other predators are in the area?

Over the next couple of days I saw some more signs, including a large cat's footprints by a pond. Then I finally spotted the puma, bedded down in the brush, not too far from the road. After an hour or so it emerged, stretched, then gracefully climbed up over the hill. I quickly drove back around the bend where it was headed, but it had already vanished.

Andean Condors

The survival of the Andean condor is also tightly tied to that of these cats and the guanaco they feed upon. These birds aren't adapted for active hunting. They depend on scavenging large prey, where their featherless heads and necks provide better hygiene while feeding deep within a carcass. In doing so, they play an important ecological role here by removing those remains, which helps control the spread of parasites and disease that might otherwise infect live animals. Their large size is supported primarily by scavenging these large grazing animals. Even larger than the Californian condor, the wingspan of the Andean condor is the largest of any land-based bird, spanning up to 3.3m (10'10”). This allows for effortless gliding on updrafts, circling high above while looking for the fresh kills. They rarely waste a wingbeat.

Today these condors are regarded as an evolutionary anachronism. They co-evolved alongside now mostly extinct megafauna. These birds need a lot of meat to survive, which large animals provide. This southeastern region of Patagonia and the Pampas are the last area that many of South America's extinct megafauna roamed. Patagonia also is now home to some of the last remaining large herds of the megafauna that did survive this extinction event, such as guanacos, vicuña and deer. As the megafauna's range and population declined so too did the condors' range. Within the Northern Andes, where game to scavenge is scarce, condors are now critically endangered, and sightings are increasingly rare. Within their broader population, including the Southern Andes, this species are now listed as vulnerable and number in the thousands.

Another more recent environmental threat the condors now face is lead poisoning. Carrion eaters often ingest the carcasses of game killed by hunters and farmers (protecting their livestock from predators or their crops from vermin). When lead ammunition is used, these scavenging birds can slowly become poisoned by it. Within North America, this was the most common cause of death for the California condor. By the 1980s their population had dropped to just 22 birds (Finkelstein et al., 2010). While still endangered, reintroduction program and a shift by hunters towards using steal ammunition has allowed their numbers to since rebound to 400 in the wild in 2010. It's a rare success story of a species being brought back from the brink.

While less study of lead poisoning has been done on their South American relatives, dosing studies have similarly determined that “once exposed to lead, the possibility of survival is poor … where otherwise healthy birds exposed to metallic lead quickly succumb” (Pattee et al., 2006). One study analyzed the condor feathers from Patagonian roosts and found that 4.6% of those tested had lead levels that exceeded dangerous levels (Lambertucci et al., 2011). If the populations of these birds are going to recover, these studies have recommended that we should try to restrict hunting where condors are found, and more importantly, to ban the use of lead ammunition in these regions, instead requiring steel ammo. Hunters wanting to reduce their wider ecological impact should also consider willingly switching to steel shot.

Within the protected confines of Torres Del Paine National Park these environmental challenges are less of a concern. Condors had been gliding far overhead for days, but I was yet to get a close look. There was one mountain that they had been returning to, the aptly named Mirador Condor. After clambering up multiple terraces and out along a ledge. I found their roost, then patiently waited. After watching them circle for a while, before long I was rewarded with the arrival of three large birds. They landed to my right and stretched their wings, resting and basking in the warm sun before returning to the air.

The Web of Life

The populations of these species hang in a delicate balance. Even with slower reproducing megafauna, over the long run their populations will tend to grow exponentially, until they reach limits imposed by their environment (Wilson, 2012). There are various kinds of these environmental constraints. For example, over-population of herbivories can result in over-grazing of land, reducing the variety and abundance of vegetation. This decline in their food supply can result in periods of famine for those grazers. This is why farmers must rotate the fields grazed by their livestock. Growing animal populations can also lead to more rapidly spreading diseases and parasites if groups become too dense, providing another limit to growth.

Further up the food chain, another environmental constraint is the fluctuating equilibrium that occur between predator and prey species. A growing population of prey species will support an increasing number of their associated predators, which helps to keep the prey population in check. Inversely, the density of predators is highly dependent upon their available prey. If these predators reproduce too rapidly, they'll eventually exhaust the limits of their food supply, where these carnivores too will face famine. This can also lead to fatal fights between these predators, battling for control of productive hunting grounds (Elbroch & Kusler, 2018). The resulting reduction in the predator population then eventually allows the prey numbers to recover. Consequently, these size of these predator and prey populations often swing up and down, oscillating over decades (Akcakaya, 1992).

As with all grazers, the guanacos need a lot of space to roam and feed. And with the guanacos' nearly yearlong gestation period, a large supporting population is needed to sustain each puma. Depending on the density of prey, tens to hundreds of square miles of grazable land might normally be necessary to support a single cat. And so, the pumas' range is typically defended against other cats. It'll use scent markings to warn of its claim to territory. Even males and females who encounter each other are at risk of confrontation if she's not in heat. In most places this behavior is acquired via biological necessity. The alternative would be starvation if the predator population were to exceed the carrying capacity of the land, becoming too numerous for the available prey. And so as with humans, competition over scarce resources can lead to conflict.

In Torres Del Paine, however, due to bans on farming and hunting, the guanaco population has been allowed to recover. And unlike North America, Patagonia has no gray wolves, grizzlies, black bears, lynx or coyotes for mountain lions to compete with. Nor does the range of South American spectacle bears, maned wolfs or jaguars extend this far south. In turn, this region now supports a much larger mountain lion population. There is enough food where their territory can sustainably overlap with that of other cats. Some cats here even remain in groups, sharing prey, exhibiting much more social behavior than is normally seen within the species. This behavior has rarely been seen elsewhere (Palmieri, 2017). This behavior has only rarely been seen elsewhere, and then it's most likely to be just between females, their cubs, and/or only a single territorial male (Palmieri, 2017; Elbroch et al., 2017).

There are few places left on Earth where ecosystems still exist in a such a natural state. Often those places that we regard as wild only appear so in comparison to the urbanized world in which we now live. After spending decades photographing wildlife, Torres Del Paine is one of the few regions I've traveled to that feels close to pristine. This abundance of large animals was once far more common throughout the planet. The conservation of habitat has allowed the species that reside here to once again thrive, with food chains still intact, enough density of game to support a healthy population of large carnivores. Our collective understanding of ecosystems is still progressing. And yet we have come a long way since the environmental movement started just a few decades ago. It's encouraging to see places like this where the ecosystem is recovering, where threatened species are beginning to bounce back. We are learning to see the longer-term impacts of our actions, finding a new balance with nature, discovering the value in preserving the web of life.