The Kingdom of Rarities (3 page)

The string of insults to nature brought about by human activities covers a staggering range including habitat loss, poaching and the consumption of body parts of rare creatures, introduction of diseases and invasive predators, expansion of agriculture to feed a growing human population, and the horrors of war. In this book I examine these human-induced causes of rarity, along with many natural influences, in a journey that spans most continents. In the natural world, the causes of rarity are often difficult to pin down or isolate to a single source. To untangle these strands, in each chapter that follows I sample different manifestations of rarity and consider
probable causes and consequences for species and the ecosystems they inhabit. Much can be done in the short term to preserve species populations. Ultimately, though, the future of many species depends on our ability to live in greater harmony with the rare creatures among us. In Bhutan, the setting of chapter 9, where Tibetan Buddhism is the dominant religion and cultural conservation is part of the fabric of society, we see how rare species can persist and recover when humans coexist peacefully with wildlife and treat rare species with respect and compassion.

What is in store for rare species? Looking backward and examining evolution's fingerprints may provide some clues. The renowned ecologist Gordon Orians has noted that natural selection, as an evolutionary process, lacks foresight. It can't look ahead to help a species best adapt to a threat to its future survival, be it next year or several centuries or millennia hence. Thus, all the current traits and behavioral responses we see in such species as the maned wolf, the giant anteater, the rhinoceroses, and the Kirtland's warbler—all protagonists in this story—were shaped in their predecessors' environments. Yet some of those traits, even if selected for other reasons, may enhance persistence when a species becomes rare or, if it has always been rare, faces even more dramatic threats to its survival. Phrased another way, at least some species that have always been rare may possess traits that will allow them to hang on in the face of changing circumstances. In each chapter I examine such traits to assess whether such a repertoire, however unintended, enhances adaptation to life in the Anthropocene.

If the search for rarity and an understanding of its origins holds evolutionary interest and conservation importance, it also has a strong allure of its own. The truth is as simple as it is universal: we are seduced by rarity and novelty. Scientists live with this affliction, shared with art collectors, car buffs, and wine connoisseurs, many of whom are willing to pay exorbitant prices to add the rarest of items to their collections. The allure of the rare is what motivates many of us to raise a pair of binoculars—from the birder who scans
the backyard feeder in hope of seeing an off-course migrant to the ornithologist who finds the now rare green peafowl in a Vietnamese jungle. Perhaps our search for rarity among wild things is a holdover from distant ancestors who sought to expand their monotonous diets, find new healing herbs, or discover a more potent aphrodisiac. A rare object might even have served as a status symbol and increased mating success. Whether stimulated by curiosity or by our most intense cravings, we humans, it seems, long to seek out what is scarce and, therefore, precious.

In the nearly forty years I have been studying rarity, a recurring fringe benefit has been the chance to visit exotic places and meet fascinating people in the search for spectacular species. I first heard the term “quest species” from Bruce Beehler, a scientist featured in chapter 2 who explored the most remote mountain range of New Guinea in search of rare birds of paradise. “A quest species,” he imparted, “is a rare species, for sure. But it is also a nearmystical creature, one that shadows your existence, one that you must see before you die.” Although avian specialists are famous for their single-minded pursuit of one bird or more for their life lists, they are far from unique. Primatologists scan the thickets for their quest mouse lemur. Herpetologists work the bushes for their prized chameleon. Botanists slog through swamps to find an orchid previously unknown to science. Even parasitologists seek their quest tick, embedded perhaps in the nether folds of a wombat or Tasmanian devil.

The study of rarity is of vital importance today, but it also allows us to glory in the extraordinary activity and variety of the natural world. Staring at a habituated rhinoceros in Nepal or contributing to a desk study on rarity, for example, can never replace the thrill of a first sighting: a rare species you have waited your entire life to see on its own terms, in its own place. A quest species, if you will.

I was on my way to the Amazon lowlands of southeastern Peru when I had the chance to see a rarity up close that I had always dreamt about. Before dawn, flashlights in hand, my guides led me to a bird blind at the edge of Manú National Park, where we waited
for the show to begin. Few rare species seek more attention than the flamboyant Andean cock-of-the-rock we had come to see. The male's molten-orange plumage virtually glows in the dark. His vocalizations—a series of hoots, growls, and chimp-like whimpers—accompany a ritualized shake of an unusual cowlick and rump. The bird's name, dare one ask, is a reference to its habit of nesting in rock walls rather than some biological double entendre.

Three male Andean cocks-of-the-rock (
Rupicola peruvianus
) singing, with a female in the background

The male's extravagant appearance flares when several of them gather in the dank, kaleidoscopic undergrowth. As the dawn light filters through the tropical highland forest of Peru, colorful bachelors scramble to their singing perches on nearby tree branches. Biologists describe the location of the courtship that ensues as a lek, a place where males congregate to advertise their individual greatness. One bird triggers an explosion of song and dance that
lasts for minutes. Just as suddenly, they all go mute. Perhaps the shadow of an eagle has passed overhead? Then the cacophony resumes in earnest. Soon a drab maroon bird slips into the center of the gathering, sparking a more intense bout of singing and feather shaking. The female has arrived.

By 6:45 a.m., the males had quieted down and dropped into the dense foliage. I left the bird blind with my guides and strolled down the dirt highway to the nearby lodge. It's hard to avoid descending into cliché after witnessing a lek display of any bird or mammal. For me, it was a lifelong yearning now sated, replaced by a sense of awe in how evolution and the essential mission to procreate can go to such lengths.

My group enjoyed a celebratory breakfast in the café of the Cock-of-the-Rock Lodge. Accessible cock-of-the-rock leks in nature, such as the one we visited, are rare and usually reached only after a long hike. Over a second cup of coffee, the conversation spun in a widening gyre of questions: What if the glorious Andean cock-of-the-rock, one of the most colorful birds on the planet, were as ubiquitous as the house sparrow? Would anyone bother to look at it? Or would its fate be like that of the blue jay, a stunner for visitors to the United States but a backyard fixture evoking yawns from the locals?

Back on the trail, we heard the males start up another chorus. Left to their own devices, most rare species, like this charismatic Andean bird, would persist for several million years. A logical conclusion, one that will be explored and challenged in this book, is that rare species have adapted to cope with life at low densities, in small areas, or in restricted habitats. Unfortunately, wild nature is no longer being left to its own devices, and many species face a tenuous future. Our own species, now shooting past 7 billion and far from rare, faces a different challenge: how to live sustainably without destroying the last strongholds of rarity. For rare species, the struggle is to hang on for dear life until, one day, humans gain the wisdom and humility to share nature's kingdom.

I
N
1704,
A
S
COTTISH BUCCANEER
by the name of Alexander Selkirk was abandoned by his captain on a remote, uninhabited island off the coast of Chile. Selkirk had become a nuisance aboard the
Cinque Ports
, telling his fellow mates that the ship was unseaworthy. None heeded his warnings nor his invitation to join his party of one; all preferred instead to sail on with their commander. It was a bad choice in the end: the
Cinque Ports
later dashed on the rocks and many of her crew members drowned in the surf.

Soon after Selkirk headed inland to seek shelter, a large, reddish hummingbird flitted past him. How strange to encounter a hummingbird on an island in the South Pacific Ocean nearly 700 kilometers off the coast of Chile. Yet the Juan Fernández firecrown (named for the cluster of islands that included Selkirk's new home) was one of the few native vertebrates sharing this remote outpost with Selkirk and some feral goats introduced by earlier sailors. Selkirk
spent the next four years as a castaway, alone, living off goat meat, wild fruit, and greens. He was eventually rescued by one of his former shipmates and returned to England to some acclaim.

The tale of the hummingbird and the marooned sailor took place on an island called Más a Tierra, which might seem irrelevant except that it now goes by the name of Robinson Crusoe Island. Literary historians have hypothesized that Daniel Defoe's novel, first published in 1719, was inspired by Selkirk's ordeal. Others have disputed this claim, pointing out that Defoe set his hero down on a tropical shore resembling Tobago or Trinidad rather than the more temperate Juan Fernández Islands. Regardless of the venue,
The Adventures of Robinson Crusoe
remains one of the most widely read pieces of fiction of all time.

The hummingbird has drawn less fanfare, but it has its own interesting side story. Unlike Selkirk, the firecrown was a longtime resident, having arrived on the island slightly less than a million years earlier. The firecrown is endemic to Robinson Crusoe Island, meaning that this island is the only site on Earth where it can be found. The total firecrown population is estimated to be 700 to 2,900 individuals, down from as many as 10,000 individuals earlier in the twentieth century and considered critically endangered today. Another, related hummingbird found on the island, the green-backed firecrown, arrived in the nineteenth century. Unlike its close relative, the green-backed is widespread in its range, being common across Argentina and Chile, and it is easily twice as numerous as the endemic hummingbird on Robinson Crusoe Island. Among the 330 species of hummingbirds in the world, though, these are a rare brace, the only two to have reached an oceanic island, reproduced, and gone on to live such a remote life.

Early nineteenth-century naturalists surely read Defoe's classic novel. And the most famous, Charles Darwin, passed near what is now Robinson Crusoe Island as the HMS
Beagle
set sail for the Galápagos Islands from coastal Chile. If Darwin had visited, it's hard to imagine his not mentioning with interest the presence of
hummingbirds on an oceanic island, so far from the mainland. The modern explanation of why one hummingbird species is found only on a dot in the South Pacific while another, closely related species has a much broader range and is much more abundant is straightforward. The endemic red-backed species, the Juan Fernández firecrown, evolved over time into the distinct species it is on the islands, whereas the green-backed is too recent an arrival on the island for it to have diverged from its mainland relatives. For many other closely related species, however, the riddle of why some are common while others are rare remains to be answered.

Endemism epitomizes island life, especially along the equator. And among biologists, tropical islands crowd the atlas of daydreams—not just for the idyllic scenery but also because the unusual, and often rare, plants and animals inhabiting such islands showcase the arc of evolution. This scientific fascination has noteworthy milestones. Darwin's visit to the Galápagos and Alfred Russel Wallace's journey to the Malay Archipelago two decades later gave rise to these two men's vision of evolution by natural selection, the greatest organizing principle of life on Earth and one that sheds much light on the issue of rarity. Natural selection, at its essence, is the evolutionary process that results in living creatures becoming well suited, or adapted, to their locale. Darwin and Wallace's theory views evolution by natural selection as the dynamic force by which individuals that possess certain advantageous features, or traits, are more likely to survive to bestow these heritable traits, and duplicates of the genes that code for them, on future generations. The sum of these traits increases what is called the reproductive fitness of an individual, and the metric biologists use to assess this quality is the offspring one leaves behind and their ability to survive and breed.

Biologists still marvel over the explanatory power of the theory of evolution by natural selection, a lens through which to view every aspect of the natural world, from the habitats wild species select to the foods they eat, the mates they choose, the places they sleep,
and their responses to predators. Yet few are aware that its coinventor Charles Darwin was also one of the first scientists to highlight rarity in nature. “Rarity,” he stated in a neglected sentence from
On the Origin of Species
in 1859, “is the attribute of a vast number of species of all classes, in all countries.” Had he expanded on this theme—perhaps in a sequel called
On the Origins and Ubiquity of Rare Species
—the topic of rarity might have become more central to the scientific orthodoxy much earlier.