For a long time before the planes crashed into the upper levels of the World Trade Center in 2001, songbirds had been in the habit of doing so, migrating by night and mistaking the lights high above the city for stars. At least one ornithologist used to stroll along the base of the towers in the early morning, removing small corpses and rescuing the living. A lot of species have been too fragile, too particular in their requirements, to survive our wholesale transformation of their environment. The Brown Satyr butterfly, endemic to San Francisco, where I live, became extinct sometime in the 19th century, and the Xerxes Blue vanished during World War Two when its Golden Gate habitat was overtaken by military expansion. A number of other local species – the Bay Checkerspot, the San Francisco Garter Snake, the Mission Blue butterfly – are near extinction. Further afield, the few dozen remaining California Condors, with their ten-foot wingspan, continue to hover at the brink of disappearance; after an ingenious captive-breeding programme, a few have been reintroduced in the wild, where they show an unfortunate penchant for flying into powerlines and eating the lead shot in game killed by guns. On the other hand and the other side of the country, one of North America’s showiest and most famously extinct birds, the Ivory-Billed Woodpecker, reappeared in 2004 and was publicly announced to still exist after all in the spring of 2005, amid a media circus, scientists’ tears, a lot of astonishment and rapture, and a little Arkansas forest protection. Whether there is a breeding pair, and not just a single individual, remains to be seen, as does the bird’s ability to make do with what habitat it has left.
There are more surprises. In mid-January, the National Park Service announced that 27 new species of spiders, scorpions, centipedes and other small creatures had been discovered in caves in two parks in California’s Sierra Nevada range. They include a relative of the pill bug so translucent that its internal organs are visible, particularly its long, bright yellow liver. There is also a daddy-long-legs with jaws bigger than its body, and a tiny fluorescent orange spider. The species are as yet unnamed.
Other species have rebounded, notably the elephant seals that were hunted nearly to extinction at the turn of the 20th century, when at most a few hundred survived in Mexican waters. They first returned to their California coastal breeding grounds in the 1950s and have since flourished north and south of San Francisco, where their spectacular sex and violence – the bellicose males weigh up to three tons – can be observed every winter. Dozens of species of birds once threatened by DDT have increased in number since the pesticide was banned, as have whales since the 1949 near-ban on hunting, though many, many species continue to lose ground. Yet others, notably a lot of omnivores and carnivores that once feared humans and were hunted by us, have begun to rebound and to expand their territory, their diet and their habits. They are joining us.
Thus the mountain lions of Silicon Valley: a Palo Alto naturalist reports that after 16 unconfirmed sightings in nine years, there were suddenly 30 sightings in the first nine months of 2004, two of which were so flagrantly deep in suburbia that police decided the predators had to be shot. One primary school sent warnings to parents against letting children walk to school alone. In a few cases in the past decade or so, mountain lions have hunted, killed and partially eaten solitary runners; in several others, they have stalked children out with their parents. We are, after all, as food units sized much like deer and not nearly as speedy. More often the lions, which can grow to be 150 pounds, dine on house-pets (as do alligators in Florida, another population on the rebound). There was a bounty on California mountain lions into the 1960s – they were wary, seldom-seen beasts in those days – but in 1990 we voted to make them a protected species. In 1920, there were about six hundred in the state; there are now four to six thousand of them. The human population has increased tenfold since 1920; the lions have changed their behaviour, no longer shunning people or habitation.
In the last decade, we have seen the emergence of the new nature that is likely to survive while the more fragile primordial nature falters. It’s a weed-like, flexible, tough set of species which thrive on the disturbances that send others into flight or extinction. And they’re becoming increasingly urban. For a long time cities had little but pigeons and rats for urban wildlife, but foxes have moved into London, and coyotes, raccoons, skunks, ravens, crows and more have moved into North American cities. For one thing, they like garbage. For another, we have stopped killing them and everything else that moves. From their perspective, we have become a relatively harmless species (except for our cars, but roadkill is a popular food source for crows, ravens, coyotes, vultures and others). They’re no longer afraid of us. We’ve cleaned up, too: the toxic sewers that surrounded Manhattan in the 1960s have gradually come to resemble rivers again, in which fish can swim and herons can hunt. The urban air is cleaner.
A lot of these species are enchanting to us urbanites unworried about lambs or crops. When a coyote appeared on Bernal Heights in San Francisco, it became a local celebrity, though other coyotes in the city have remained relatively unfêted. (Angelenos must have scoffed at our excitement, since choruses of howling coyotes are old hat in the canyons and hills that edge their city.) Raccoons, with their bandit masks and ringed tails, have soared to bear-cub sizes on their garbage diet and become bolder and bolder; I often see them out strolling across streets, under cars, and up fences around the time the bars begin to empty. Ecologically speaking, these species are mostly harmless: the supply of house-pets, runners and garbage is not about to dry up.
Ravens and crows are another story. Seventy-five miles up the coast from San Francisco, Alfred Hitchcock made The Birds, in which a Coalition of the Winged attacks human beings en masse, a fantasy in its depiction of unity between avian species as much as anything else. Some birds have proliferated to an amazing degree in the last decade or so, notably ravens and crows, but they threaten the survival of more fragile species. One of the still-endangered species of the West Coast is the Snowy Plover, and by 1995 ravens were plundering more than two-thirds of their eggs on the seashore north of San Francisco, as well as raiding nests of other at-risk species. They have been observed preying on Bank Swallows in the Bay Area and the Marbled Murrelet in the Pacific Northwest. A pair of Bay Area ornithologists trying to protect other birds said: ‘We go to great lengths – hiding the traps, hiding ourselves, starting before dawn. It’s difficult to outsmart them.’ They are very smart and, unlike most birds, great learners and interpreters.
A young naturalist who grew up birding in San Francisco – we have Great Blue Herons in Golden Gate Park and a considerable seabird population on the beaches – told me he considered ravens and crows to be tantamount to a ‘second Silent Spring’ (the first being the destruction of birds by DDT and other pesticides, which Rachel Carson addressed in her 1962 book). When I came to San Francisco, ravens and crows were a rare sight in urban spaces; they had become rare altogether in the 1920s, but populations since the 1980s have exploded. In the San Francisco Christmas count of birds, ornithologists found 14 ravens in 1983 and 239 in 1999, while Oakland went from five to 101. They appear to have increased far more since then. I see ravens often, sitting on the powerlines outside my windows, their bulk of ruffled feathers making them look middle-aged, dishevelled, unlike their sleek cousins the crows, which are also all over the place these days.
In the deserts east of Los Angeles, ravens are even more devastating. There the highly endangered desert tortoise still roams, and although habitat loss and being run over by cars and off-road vehicles severely affect their numbers, the ravens may be a worse danger still. The birds have become what the wildlife biologist Michael Soule calls a ‘subsidised species’, meaning that they have a stable food source in garbage, as house-cats preying on songbirds do in cat food. Urban garbage dumps around the edges of the deep desert have encouraged a population explosion among ravens: this is one of the many ways population increase can destroy habitats at a distance. Adult desert tortoises are as tough as anything in a shell, but the thinner-shelled young are for the first five or six years of life extremely vulnerable to ravens. Beneath one raven’s nest in the Mojave desert, naturalists found 250 baby tortoise shells.
The success of the raven means the failure of other species, also valuable, so the very sight of these creatures, especially in new places – like outside my window – is ominous. Tortoises are sacred to some of the Mojave’s local tribes, while the raven is, in the mythology of the Northwest coast, a creator deity. That something sacred or symbolic can become a weed and a pest is disturbing. A raven used to be an oracular sight, an omen, impressive, noble, wild; now it is bad news, a weed, trouble. This decline is worrying not just in what the birds do but in what they mean. And it turns the creatures from being part of an ecosystem into its destroyer, the birds acting as agents of our own disruptiveness. Ravens, like coyotes, may have been creator deities because they are rather like humans in their ability to adapt, improvise, change, to trick and to shift. Perhaps in seeing ravens go wrong, we might see ourselves.
In recent years, a number of books have taken on ravens and crows, members along with jays and magpies of the family corvidae. Bernd Heinrich’s Ravens in Winter (1989) describes their communitarian survival strategies, while Candace Savage’s Bird Brains: The Intelligence of Crows, Ravens, Magpies and Jays (1995) takes a wider look at the workings of the quite complex corvid mind, which learns, adapts and, in the case of some crows, can even figure out how to make and use tools, while others become skilful mimics of other birds and of people. Savage cites at least one scientific study by Tony Angell and several by John Marzluff, the co-authors of a new illustrated book, In the Company of Crows and Ravens. A generalist’s book written by experts, its text considers the role of crows in the human cultural imagination and provides information on their behaviour. Angell’s drawings sometimes sink into cuteness, as in one picture of crows picking dead insects off the grill of a car on which the licence plate reads corvid. They know their subject intimately, but not their readers, to whom they often over-explain basic concepts.
At times engrossing – for example when revealing the ancient tradition of raven-keeping in the Tower of London as a myth of recent origin – Angell and Marzluff’s book is more often meandering and bland, as when they mention for the second time the Three Crow brand of spices in Maine to bolster their case for the cultural importance of crows. Even their debunking of the myth that ravens have been kept in the Tower since the time of Charles II concludes: ‘The power of ravens to make people believe the impossible and survive difficult times is obvious.’ Like many popular science books in recent years, this one claims its subject as the world-changing event, phenomenon or invention. Crows and ravens matter – they’re in the Bible and Norse mythology and the Northwest creation stories, as well as on the wire outside my window – but they’re not that central or powerful, or cheering: the likelihood that the idea of protective ravens really spurred on the British during the Blitz seems a little far-fetched.
Bird Brains does a better job of describing the remarkable intelligence of these birds, but neither book quite captures their threat. In fact, Angell and Marzluff write that ‘demonstrating an ability to find and prey on nests efficiently does not necessarily mean that crows or ravens limit other bird populations.’ Sixteen pages later, we are told that the house crows imported to Zanzibar by the British governor in 1891 ‘reached half a million in Dar es Salaam alone. They are spreading across Africa, threatening rare birds and annoying people.’ Tokyo has seen its crow population quadruple since the 1980s, fuelled by accessible garbage.
In themselves, ravens and weed-like plants – the Himalayan tree-of-heaven, for example, which can be found all over the rubbly and neglected margins of cities from Berlin to Detroit – are admirable and even beautiful. But they function as a biological equivalent to Burger King or Microsoft; they threaten to become transnational monopolies that force out the local versions. Indeed, you can see the one as a by-product of the other: the industrialised world that creates garbage, cities and shipping (which often transmits the weedy species from one continent to another) encourages these species to move out of their former niches and proliferate. It’s not a coincidence that the crows invading Africa came as part of the imperialist package.
Climate change will root out other species of animals and plants: the Yellow-Bellied Marmot, which lives in the high Rockies, is dying out because the thaws now often come too early, before the plants they eat have started to grow. Wolves, too, successfully reintroduced after being hunted to near-extinction in the US, get through the winter by eating elk weakened by cold and the snow that covers their foodstuffs; with warmer winters the elk thrive and the wolves starve. Red foxes are moving north to compete with arctic foxes. This will leave in most places a brutally simplified ecology, with lots of trees-of-heaven, dandelions, robins, ravens and raccoons: what David Quammen calls ‘a planet of weeds’, though if we ourselves, the chief weed, become extinct or get scaled back, even these weedy species may begin evolving into creatures more delicately adapted to specific niches. But that is the million-year view, not the thousand-year version. In the meantime, what’s sauce for the raven is poison for the Snowy Plover.