You might have heard of a pangolin. Or you might not have.

But Rainforest Trust’s Outreach & Communications Team wanted to show you the pangolin’s true anatomy. We hope that learning more about this animal found in Africa and Asia will lead you to learning to love the eight species of pangolin as much as we do. And, of course, we hope you’ll help protect them from extinction.

Original photo of Critically Endangered Sunda Pangolin by David Brossard.

This shy mammal has the distinction of being the one of the least known and most trafficked animals in the illegal wildlife trade. The pangolin’s Armoured Floof is attractive to many across Asia, as the scales are thought to hold major medicinal properties. And with a Chonk Level of 100, the interest in hunting pangolins for meat is a prominent problem.

While the pangolin’s main defense against poachers and other threats is curling into a tight protective ball, it does have Legs for Zooming if it needs to enter PanGOlin mode.

The pangolin subsists on ants and other insects, using T-Rex Hands to dig into termite mounds, and its Snack Sniffer to root out savory larvae. Some folks refer to pangolins as scaly anteaters, but a more apt title is “Artichoke with Legs,” considering its armored adorability. The pangolin’s Honestly Too Cute Face is enhanced by its Cuteness Extension on the other end.

It is estimated that 2.7 million pangolins are poached each year, so this World Pangolin Day, consider donating to save pangolin habitat in Nepal. All of your gift will go directly to conservation action at our project site, including being used to hire forest guards who ward off the biggest threat to pangolin survival: Us.

Click here to learn more about the plight of the pangolin.

Rainforest Trust’s work to protect habitats for threatened species is grounded in cutting-edge conservation science. But in this series, we explore the basics of conservation science and how they inform Rainforest Trust’s scientists.

What is a species?

No, I’m serious — let’s come up with a definition.

Alright, well, we know specific species, like Polar Bears. A Polar Bear is a species of bear, which is a mammal, which is an animal, which is a living thing. (For more on taxonomy, see my article on spaghetti.)

A different species of bear would be the Brown Bear (AKA the Grizzly Bear). The Polar Bear’s scientific name is Ursus maritumus. The Brown Bear’s is Ursus arctos. They have different species names — making them different species.

But how did we decide this?

There’s got to be a standard system for determining where one species ends and another begins. Right?

Wrong.

Turns out, there are three systems for determining where one species ends and another begins. We have our physiological species concept where species differ by physical traits. We also have our ecological species concept where species differ by geography and which ecosystems they occupy. Finally, we have our genetic species concept where species differ by differences in their DNA.

“Hold on, hold on, hold on,” you might be thinking. “Isn’t evolution like a tree, where each species is the end of a branch? Shouldn’t it be simple to tell the difference? How could we disagree over where one species ends and another begins?”

My copy of Dictionary of Ecology by Herbert C. Hanson, published in 1962 by Philosophical Library and picked up by me for free in 2015 at a give-away by the Cleveland Park Library in Washington, D.C., defines a species as:

“A unit of classification of plants and animals, consisting of the largest and most inclusive array of sexual reproducing and cross-fertilizing individuals which share a common gene pool.”

Nature, the infamous science journal, defines a species a little differently in their online learning resource:

“A biological species is a group of organisms that can reproduce with one another in nature and produce fertile offspring. Species are characterized by the fact that they are reproductively isolated from other groups, which means that the organisms in one species are incapable of reproducing with organisms in another species.”

Neither of these definitions are (entirely) correct. (Cue: gasp)

Both come down to a few ideas.

1 – Members of a species can reproduce with another in nature.

2 – Offspring must be fertile

3 – They must be reproductively isolated from other groups — one species cannot reproduce with another species (“largest and most inclusive array of sexual reproducing and cross-fertilizing individuals”)

Here, I found two definitions of a species: one from a world-renowned scientific journal and one from some random book I got for free on the sidewalk once. But they both miss something big, gnarly and strange.

The Pizzly Bear. That’s what happens when a Polar Bear and a Brown (Grizzly) Bear mate. They create a Pizzly Bear. Otherwise known as a Grolar Bear.

As we established before, Polar Bears and Brown Bears are different species. They have different names! But let’s break them down into the three species concepts:

Physiological Species Concept

Polar Bears have white fur and adult males usually weigh somewhere around 1000 lbs. Brown Bears have brown fur and adult males usually weigh somewhere around 500 lbs.

The two species differ in other, more specific ways, but physiologically, they look like different species.

Ecological Species Concept

Polar Bears live in oceanic, arctic climates, in Northern Canada and Alaska, through Russia and Norway. Brown Bears live in the Northern Hemisphere also but in terrestrial environments and range much further south than the Polar Bear.

Ecologically, they seem like different species.

Genetic Species Concept

I don’t have the DNA results on hand, but we can probably assume there‘s some DNA differentiation.

Hence, genetically they (probably) seem like different species.

But let’s go back to the two species definitions and their caveats. They both came down to species differing from one another by the ability to reproduce and create fertile offspring. Here’s where Polar Bears and Brown Bears miss that mark.

Where the two species overlap, people have documented the rare but definitely occuring-in-nature Pizzly Bear. The Pizzly was first discovered in 2006, with a few more discovered since then. Theories speculate that all the bears are descendants of one female, making this a unique case. In fact, some ecologists believe this never would have occurred without the impact of climate change — a warmer climate pushed Brown Bears further north and into more of the Polar Bear’s range, increasing the likelihood of contact.

But no matter what the cause, the two species could reproduce. What’s more, researchers believe some of the Pizzly bears found are descendants of a Brown Bear and a Pizzly Bear! Meaning, not only could they reproduce, but the offspring can be fertile!

This isn’t the only instance of hybridization occuring in the wild. Narwhals have mated with Beluga Whales. Dozens of bird species hybridize, often proving an identification challenge for birdwatchers. Napolean Dynamite’s pretty-much-favorite animal, the Liger, however, does not exist in the wild as Lions and Tigers have no overlapping range. But it does exist in captivity. That big cat actually has a thorny ethical reality.

Yet Brown Bears and a Polar Bears are so clearly different species. Where does this leave our species definitions?

Neither is right. But neither is wrong. If I were to ask a random grouping of 1,000 ecologists, evolutionary biologists and taxonomists their definition of a species, I doubt I’d get two of the same answers. It’s not that no two would be worded the same — it’s that no two would be the same in their caveats. I’d likely get a few pages-long essays. I’d likely get a couple of laughs and a “No, thank you.”

Biologists debate this topic all the time. They also debate whether species are best divided physiologically, ecologically or genetically. A lot is up for debate. And that’s great! You know, scientific discourse and all that.

Sometimes scientific progress prompts us to revise species boundaries to divide two groups, but sometimes we merge two groups. Sometimes one species living on two different islands or mountains are actually two species. Sometimes two species living on two different islands or mountains are actually one species.

It’s always changing. But that’s part of the fun.

I wrote this to give you more answers. I’m realizing I may not have been entirely successful. Sorry. But now you know how weird, complicated and nebulous some elements of taxonomy can be. I guess that’s an answer to something, maybe.

Point is — if you ever see a dusty white/brown bear, somewhere way up in the taiga, take a closer look.

Ever see a field guide to the trees of North America? They’re hefty, with lots of pictures or drawings of elms, poplars, spruces, maples and such.

But have you ever seen a field guide to trees of a tropical region, such as the Chocó or the Congo Basin? I haven’t. And you know why?

Because it would be massive. Like… unpublishable.

The Sibley Field Guide to Trees of North America covers over 600 species. 426 pages.

A Field Guide to the Families and Genera of Woody Plants of Northwest South America? 920 pages. And it only covers families and genera — not even every specific species.

Ecologists and naturalists have long known that tropical forests are home to a higher tree diversity than temperate forests. This makes sense — tropical ecosystems often have higher species diversity.

But, as the authors of a new paper (whose findings I’ll get to) start off by saying, the ecological work of drift and species competition tends to reduce diversity in individual ecosystems.

To oversimplify:

Drift refers to what will happen in a population as it reproduces. Dominant traits become more prevalent and recessive traits become less prevalent. (Everyone remembers their high school biology class?) So dominant traits tend to win out and replace recessive traits, and the overall diversity of a population decreases.

Species competition is when two species who use the same resources, or occupy the same niche, compete until one species wins and the other moves elsewhere or goes extinct. So, by eliminating one of those species, competition reduces diversity.

These two phenomena should mean that in individual ecosystems, one species should dominate each niche, with maybe a few other rarities present. This is true in both tropical and temperate ecosystems. The tropics have higher biodiversity despite this (at least in part). Tropical areas have more isolated ecosystems per area and more resources, leading to more niches in those ecosystems.

But why are some individual ecosystems in the tropics home to upwards of1,000 tree species?

You would think, based on the processes of drift and competition, that one or even a few species should dominate tropical forests. Not so fast.

“In the tropics, all of the tree species appear to have a similar competitive advantage,” says Taal Levi of Oregon State University, lead author of a recent paper describing an explanation to this staggering diversity. “There is an abundance of species, but few individuals of each species… there has to be a mechanism that keeps one species from becoming common, becoming dominant.”

Turns out, such a mechanism does exist.

The paper describes how microorganisms — sometimes fungi and arthropods — who live in the soil around trees target the seeds of individual tree species. As the trees drop seeds, these microorganisms attack them. But they only attack the seeds of that one species. They don’t care about seeds from other species.

But these creatures live in “rings” around the trees in question, not everywhere. So if a tree’s seeds happen to end up further away, such as after a ride on the wind or a bird, they can germinate and grow, no problem. Of course, those seeds are less numerous than the seeds that fall to the ground near the parent tree. Those apple-fell-not-so-far-from-the-tree seeds? Murdered by a fungus.

These specialized microorganisms can prevent individual species from taking over an ecosystem. And this could explain the sky-high tree species diversity even over small areas of tropical forests. No one species can gain a foothold on domination because dropping a whole bunch of seeds nearby won’t do anything. This theory was actually first proposed almost 50 years ago, by ecologists Dan Janzen and Joseph Connell. But this new paper provides concrete evidence backing them up.

So don’t worry trees, the tropical forests are all for you. What would they be without you? But if you think something is out to get your seeds…

Yeah. Something is. But it’s making those ecosystems all the more interesting.

Author Note: One of the co-authors of this paper, John Terborgh, is a member of Rainforest Trust’s Council.

A few weeks back, I met up with friends after returning from filming in Colombia’s Sierra Nevada de Santa Marta mountains. Halfway up this mountain range — the tallest coastal range on Earth — is the El Dorado Bird Reserve. Rainforest Trust and our partner Fundación ProAves have worked on protecting this property for 15 years.

“How was it?” they asked. “Where were you exactly, again?”

I relayed where, exactly, I was. And from that one vantage point in the reserve I looked out onto rainforest, mountain-top glaciers and the Caribbean Sea at the same time. And there, from said point, I spotted the Santa Marta Woodstar, a hummingbird species endemic to the range.

Meaning, I told them, that while looking at a hummingbird on a mountain, I saw land near the ocean where this hummingbird did not live. Because it only lives on that mountain.

“Cool, right?!”

“Very cool!” they said.

Unconvinced by their displays of awe and willing to hijack the conversation for at least another few seconds, I continued.

“I mean, I could look at a bird next to me, while at the same time spotting a plot of land where this bird species doesn’t live.”

For the hummingbird, the land by the ocean is, in the words of Frankie Valli, “so close, and yet, so far.”

One of my friends asked “Wait, why is that?”

You may now ask, “Why did his friends so clearly give him an outlet to begin some ecological pontification?”

Because they’re wonderful friends and they humor me.

I digress.

“So, imagine you’re a White-tailed Deer living in Rock Creek Park.” I said, gesturing toward the park a quarter-mile from our location.

“In the course of a year, you might experience temperatures ranging from -10 to 100 Fahrenheit. So deer had to evolve to live in a wide temperature range to survive in this landscape.”

“But now imagine you’re a hummingbird in the lowland Amazon rainforest. Over the course of a year, you might only experience temperatures ranging from 75 to 90 Fahrenheit. So the species didn’t need to evolve to withstand many changes in temperature. Because the climate doesn’t change much season to season in the tropics.

“But the climate does change at one place in the tropics.”

I paused for dramatic effect.

“The mountains.”

“As you go up a mountain, it’ll get colder, right? At 5,000 feet above sea level, a mountain right next to the Amazon rainforest might have a year-round temperature ranging from 60 to 70 Fahrenheit. Hence, those lowland rainforest hummingbird species won‘t spend time up there because they aren’t adapted to withstand even a small difference in climate.

“But now suppose some of those lowland rainforest hummingbirds make their way up the mountain, over the course of a few million years. They’ll adapt — over time — to the colder temperatures and spend time only up at high elevation because the offspring that will thrive and breed are more tolerant. Meaning they’ll also stop hanging out with the hummingbirds in the lowland. And after a while, those two groups of hummingbirds — the original lowland and the new mountainous groups — will diverge enough to become separate species.

“So now there’s a hummingbird species adapted to altitude. It won‘t want to fly to the lowland because it’s too hot. And now suppose the mountains are isolated from other mountains — only lowland areas surround them. The hummingbird species won’t travel anywhere off that mountain range because everywhere nearby is unsuitable habitat.

This theory first came to light in 1967 with a paper titled “Why Mountain Passes are Higher in the Tropics” by a scientist named Dan Janzen. Mountain passes aren’t actually higher in the tropics. But a deer in Rock Creek Park, living near sea level, could cross over the Appalachians with little problem. But a lowland tropical species probably can‘t overcome a similar elevational change. The species hasn’t adapted to withstand the temperature changes. So mountain passes are, as a metaphor, “higher” in the tropics when regarding species movement.

Some of his hypothesis has changed in the past 50 years, but a lot still holds up. In fact, a paper published this past November still supported many of his ideas.

This theory is also part of the reason mountains in the tropics have some of the highest levels of endemism of any ecosystems on Earth. The tropics are already the most biodiverse region on the planet. And tropical species often need hyper-specific habitats because of a lack of seasonal change. So when you put an anomaly micro-location, such as a mountain, into the equation, you’ll get many species with hyper-specific habitat requirements that only live in one anomaly micro-location.

The Sierra Nevada de Santa Marta are not only the tallest coastal mountains in the world and the tallest mountains in Colombia, they’re also isolated. If you look at them on a map, you’ll see the Caribbean Sea to the North and lowland tropics to the East, South and West. There’s nowhere else for the micro-location adapted species to go.

The research journal Science actually named the spot “The Most Irreplaceable Site for Biodiversity.” Meaning, of all the places on Earth — from the Adirondacks to Micronesia to your backyard — losing this one site would have the biggest net impact on global biodiversity.

Rainforest Trust’s project in the Sierra Nevada de Santa Marta, protecting (and now expanding!) the El Dorado Bird Reserve preserves some of this vital habitat. This reserve has always been important — anywhere deemed “The Most Irreplaceable” deserves protection. But in 2016, Colombia was home to a landmark treaty to end a decades-long civil war. The treaty ended one of the worst conflicts of the past hundred years and ushered in a new era of peace. But the new peace has also led to a changing reality for Colombian conservation. The country is now seeing a massive uptick in deforestation. Areas once held by rebel groups are now “open for business” and people are moving in.

The Sierra Nevada de Santa Marta, once an isolated area, is now seeing rising land prices and luxury homebuilding. Hard to blame someone for wanting to build a vacation home there — it’s gorgeous! But conserving the region’s unique wildlife has never been a more relevant concern.

On a grander scale, we have to start talking about the importance of tropical mountain ecosystems. Because they’re cool and diverse, yeah, but mountains in the tropics are also some of the most threatened ecosystems. They’re facing habitat loss and development, like other tropical ecosystems. But they’re also more vulnerable to climate change — for species with narrow acceptable temperature ranges, a two-degree temperature change could be a massive upheaval of the norm.

But my overenthusiastic personal excitement over tropical mountain ecology and the species-habitat relationship may be too wonky for every audience. While my friends indulge me, that doesn’t mean everyone will. But you also have friends! And you might be (read: almost definitely are) less geeked-out about tropical mountain ecosystems. So it’s up to you to explain the importance of sites like the Sierra Nevada de Santa Marta in ways that people understand.

Because without you, these sites — often remote, often inaccessible and often far away — will disappear.

So do it in your own way! Write a skit! Draw a picture! Or, if you need help, I can get you started.

Try: “So imagine you’re a White-tailed Deer.”