Why do as few as 25% of the world’s species account for 90-95% of all individuals on Earth? Why are so many species so rare? Is it all our fault, or has it always been this way? And no matter what the causes, what can we do to help preserve the rare species of the world?
The attempt to answer these questions generated both the motivation and the content in The Kingdom of Rarities, an interesting new book by WWF ecologist Eric Dinerstein.
Dinerstein asks, “Why, wherever you land, do you always find a few superabundant species and a multitude of rare ones?” He notes that “even though rare species occur everywhere, we still know too little about how they fit into the big picture of our wild menagerie.”
One of the things we don’t know is whether rarity necessarily means living on the brink of extinction. Have some rare species always been rare because they have specialized very narrowly in ecosystems dominated, at least in numbers, by other species that are better generalists? And as climate changes, will species that are currently common become rarer? Can studying species that have always been rare help us understand the situations that will be faced by today’s threatened species, who may become tomorrow’s rarities?
Dinerstein’s search for the answers to these and other questions has sent him all over the world, to the forest environments of South American and South East Asia, where rare birds and mammals are most concentrated.
Most of The Kingdom of Rarities is devoted to accounts of the author’s travels — to New Guinea, Cambodia, Vietnam, and Bhutan, among others — to find, observe, and study the rarest of the rare. Birds of paradise that live only in a single mountain valley, elusive ruminants along the rivers of Vietnam, and many more species turn the book into a treasure trove of stories to delight amateur zoologists and birders, who will the be the book’s most enthusiastic readers, along with ecologists and environmental activists.
He cautions that “saving only one population of each rare species simply as a token gesture would be of little ecological value, especially where those species play a role in maintaining a given ecosystem’s integrity.” He calls the conservation of multiple populations “an essential goal.”
These two concerns—rarity of species and paucity of particular populations—merge when it comes to those species whose entire earthly existence is represented by a single population, as a result of either natural forces or human encroachment. Who are these singleton species, and how many of them are now close to the abyss of extinction?
Dinerstein points out that rare rain forest mammals and birds, “even at very low densities, influence the species-rich domain over which they rule.” Take a crucial rare species out of a forest, and the entire ecosystem may change, in ways similar to what we often see when a new species is introduced to a non-native environment. The delicate balance can be upset by extraction as much as by insertion, and species of animals and vegetation that flourish now may no longer succeed in an altered ecosystem.
Dinerstein argues that “the challenge ahead for us in preserving rarities is to link the science-based approach that focuses on populations rather than individuals and the animal-welfare philosophy that gives ethical value to individuals and their well-being.”
It’s a noble challenge, and The Kingdom of Rarities is a welcome addition to the seeker’s arsenal of information.