By Eric Dinerstein, author of The Kingdom of Rarities
What if the organisms that populate the natural world—from whales to weevils—were classified not by their evolutionary relationships but by their relative degree of rarity? Imagine a way of looking at the world where we divide the ark into representatives of two kingdoms: the Kingdom of Common species and the Kingdom of Rarities. Which would require a bigger ark if we only took two of each species?
Surprising facts about rare species:
1. Rare isn’t rare. Most people don’t realize that many, many species on Earth are rare. By rare, we mean having a narrow range, low population density, or both.
Ecologist Kevin Gaston estimated that perhaps 90-95% of all individual organisms on Earth represent no more than 20-25% of all species. That means that up to 75% of all species on Earth are rare in one form or another. Among the two forms of rarity, most take the former condition: species with narrow ranges.
2. Rare hotspots abound. There are about 600 places in the world that contain one or more species who call that spot the only place on Earth they can be found. Some are as large as the Javan rhinoceros or as small as 13 species of tiny frogs in the same genus that live on top of a single mountain in Haiti. Many of these single-site species have cool names, like the Bloody Bay Poison frog.
The group that has spearheaded the conservation of these single site rarities is the Alliance for Zero Extinction, which includes many major conservation groups as members.
3. Goats are enemies. Goats are a scourge when it comes to conserving rarities, especially when it comes to goats on islands, where these introduced herbivores mow down the vegetation and cause the extinction of rare plants.
Except, at least, in the island of Eleuthera in the Bahamas, where goats are a force for good in creating more wintering habitat for the rarest breeding songbird in North America, the Kirtland’s warbler. The goats prefer the shrubs that compete with the fruiting-shrubs that form a large part of the winter diet of the warbler. By eating out the shrubs the Kirtland’s avoid, the goats leave more space for the plants whose fruits the birds like to eat. The Kirtland’s warbler may also be the only species with a college named after it: Kirtland’s Community College near Grayling, Michigan.
4. Hawaii hosts a bonanza. The Hawaiian archipelago is America’s Galápagos that hosts more creatures—a group of birds called the honeycreepers, fruit flies, and many kinds of plants like the silverswords—that rival or surpass what Darwin found on the Galápagos. Had The Beagle landed in Hawaii instead of the Galápagos, we would likely be celebrating Hawaii as the cradle of evolutionary thinking.
5. Giant poo. One of the rarest of large mammals, the greater one-horned rhinoceros of Nepal and India, produces up to 24 kilograms in a single defecation. I know, because I weighed it.
Rhinos are a good example of species that were once more common in the past few centuries and made rare by humans hunting them. But the southern white rhino, now threatened by poachers again, is perhaps the greatest success story for conservation: numbering no more than 60 individuals and limited to a single reserve around 1900, the current estimate is above 20,000 and now spread among more than 450 populations. (See photos of “rhino wars.”)
So if we can recover even one of the largest, slowest breeding vertebrates in nature, we can recover many rarities threatened with extinction.
There are many insights into how the natural world works that we can only glean by studying its rarities. The challenge is that it is often much harder for scientists to study rare species than to study common ones. But if we are to save some semblance of our natural world for future generations, the roster of rarities plays an important role that I hope my book helps to illuminate.
In The Kingdom of Rarities, scientist Eric Dinerstein poses an intriguing question: What if the way we categorized the living world was reshuffled for a moment, from a system designed to inform us about evolutionary relationships among species to one with two camps based on abundance: the Kingdom of Common species and the Kingdom of Rarities? What new observations and connections would emerge? Eric Dinerstein is Lead Scientist and Vice President of Conservation Science at World Wildlife Fund-US.