A Keystone Species, Gone Invasive
By: Ryan Mccombs Jr
Tags: Animals, Ecosystem, South America, Environmental Impact, Science

A Keystone Species, Gone Invasive

Photo By Steve from Washington, DC, USA — American Beaver, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=3963858

In North America, we know beavers as ecologically important enough to refer to them as a keystone species. They can positively alter environments bringing with them a mix of other animals and plant life, even microbes that capable of revitalizing a dying ecosystem. However, this is, in part, because of North American wildlife, fauna, and woodlands evolving with the beaver. The cute bundle of bucktooth joy has had a detrimental effect on the southernmost tip of South America, an area known as Patagonia. I’m sure you have some questions. If they are such a problem, then why are they there in the first place? Why haven’t the endemic species of South America adapted to them? And now that you’ve asked yourself out loud, you probably know the answer. Humans.

How they got there

In 1946, they brought 20 North American beavers down to the Tierra del Fuego Archipelago, hoping to build a fur trade as a boost to the local economy and to enrich the native fauna. This was the brainchild of the Secretary of the Navy and Secretary of Agriculture in Argentina. It appears they did not consult with any ecologists who even in 1946 could have advised against this scheme.

Scientists traced the beavers’ origin back to Manitoba, Canada through an article written in the Schenectady Gazette on October 25th, 1946, “Lamb and the beavers traveled by rail from Moose Lake to New York, by air to Miami and will leave tomorrow aboard a clipper to Argentina.” The article references, Thomas Lamb, a Manitoban bush pilot. They also confirmed this through Lamb’s own flight records. Tracking where exactly they came from is important, so we know what animals and fauna did well with beavers around and to get a better idea of why they chose these specific 10 pairs of beavers. The answer is more simplistic than one might expect, it’s because that’s all Lamb could catch. The Argentinian Secretary of the Navy requested 25 pairs, but Lamb could not catch that many in the timeframe given. Initially, there was concern it would be insufficient, and because beavers mate for life that losing a few could be a big problem. No worries, a shortage of beavers has not been a problem, on the contrary actually, as it’s estimated there could be up to 200,000 now.

What’s been happening since

Let’s start with the bad first. As I already mentioned, the population boomed. This is mostly because they don’t have natural predators in Patagonia. In North America, the beaver population is naturally managed by wolves, cougars, and coyotes. Another major issue is that unlike their northern brethren, which have evolved with the beavers and are well-adapted to flooded soil like the ones we would find around beaver ponds in the US and Canada, the trees in Tierra del Fuego don’t re-sprout when cut down and they die from oversaturation. So what Patagonia gets is a dying land with felled and rotting trees and endemic animal species deserting the areas the beavers take over. Ultimately, the area suffers from a lack of biodiversity on the land, in the soil, and in the water.

Tierra del Fuego By Piergiorgio Rossi — produzione propria, Public Domain, Wikicommons

The fur industry never gained momentum there, and it’s in part for the difficulty in reaching these areas. For the locals, it was never worth the effort since beaver fur has not been popular in South America. Most scientists say, it is impossible to eliminate them and many are torn whether to do so even if they could because the beavers are likely to create a novel ecosystem and they’re just so darn cute. No, really, that is what’s they said.

Now for a little good. Humans create novel ecosystems quite often that nature adapts to when given enough time. It can occur when once human-occupied lands such as parking lots, mines, farms, and towns are abandoned or when we introduce an invasive species to an area. A study of the Magellan woodpeckers, a native of Patagonia, has shown they thrive in areas near beaver ponds. Scientists hypothesize the beavers’ disturbance may have increased the wood-boring insects the woodpecker so crave. Woodpeckers favor old growth, which the beavers are providing more than enough of when they flood an area and kill the trees. Some even suggest the ponds create microclimate ingredients in soil moisture which may favor the infestation of trees by wood-boring insects.

Muskrats and minks, humans also introduced to the area, have thrived beside the beavers. If not for the beavers, these animals who arrived shortly before them would probably not have survived. Muskrats eat the fauna of the area and minks have a voracious appetite for muskrats.

Another native species which does better than an invasive one because of the beavers is the Puye. They do well in beaver ponds, although it’s unclear why. The Puye outperforms the trout, another ill-advised introduction of a species to Patagonia compliments of humanity.

Final thoughts

Only time will tell at this point what the beavers’ impact will be in the long term. Some predict it could devastate the area with all the downed trees, stagnant water, and rot. Others say that nature will fix man’s mistakes, and I agree with them. I’m not a big fan of culling them, but I understand they may cause the deaths of other species, so it’s a tough decision to make. What are your thoughts?