Urban Birds of Prey: A Lengthy History of Human-Raptor Cohabitation

Keith L. Bildstein and Jean-François Therrien

POPULATIONS OF "URBAN" RAPTORS ARE increasing globally. Trained falcons are now being flown in city golf courses to scare off geese in hopes of reducing accumulated droppings along the fairways. In both the Old World and New, tens of thousands of vultures rummage through urban garbage dumps in search of humans' leftovers. In Spain, lesser kestrels (Falco naumanni) raise their young in the center of cities and towns, where they are attracted to and feed on swarms of insects flying above night-lit cathedrals and other historic buildings. Peregrine falcons (Falco peregrinus) routinely hunt for birds attracted to the brightly lit Empire State Building in downtown New York City, and red-tailed hawks (Buteo jamaicensis) nest in and around Central Park, feeding on pigeons, rats, and squirrels. Many other species serve as additional examples of a growing number of "urban" birds of prey, whose populations are increasing as human attitudes shift from a "shoot-on-sight" mentality to indifference and tolerance. But before exploring this topic further, first we will offer a bit of linguistics to explore the nuances of the phrase "urban raptor."

The word urban is believed to be derived from the Latin word urbs, which refers to a "walled city" or, specifically, to ancient Rome. Today it is used to indicate areas with high-density human settlements and is defined in the fifth edition of the Oxford English Dictionary as being "of, pertaining to, or constituting a city or town." The word first came into use in the English language in the early 17th century, thousands of years after human cities themselves first appeared.

Although raptors, more than most birds, have been heavily persecuted by humans, there is evidence that "urban raptors" began to appear simultaneously with human-created urban landscapes. Indeed, relationships between raptors and humans — some commensal, some mutually beneficial, and others still parasitic or predatory — probably predate modern humanity itself. That said, most studies of urban birds, including those of raptors, have been conducted in the past 35 years, and as such, the serious study of urban raptors remains in its infancy, with some researchers suggesting that the phenomenon of "urban raptors" is relatively recent.

Nevertheless, there has been a lengthy buildup to the phenomenon of city birds of prey, highlighted by many kinds of symbiotic relationships between humans and raptors that predate and, in many ways, foreshadow this ongoing phenomenon. Here, we cast this relationship in the light of two well-established and closely related ecological principles: habitat selection and expanded niche breadth coupled with population growth. Specifically, habitat selection results in raptors settling in landscapes that provide them with both safe nesting sites and adequate and accessible feeding sites, or in less technical terms, a safe "bedroom" and a well-stocked "pantry" or "kitchen" (an ecological connection that then US Secretary of the Interior Cecil Andrus made while proposing the expansion of the Snake River Birds of Prey Conservation Area in Idaho during the 1970s). We also look at how newfound city landscapes enable growing populations of raptors to broaden their traditional niches by including urban areas and other human-dominated landscapes in their repertoires of "appropriate" habitats.

Pre-urban Symbiotic Associations between Raptors and Humans

To understand the ecological basis of the phenomenon of urban raptors, it helps to outline the history of symbiotic relations between humans and raptors. Today many hunter-gatherers — including, for example, the Hadza of northern Tanzania — routinely monitor the flights of Old World vultures and follow these avian scavengers to large carcasses that the hunter-gatherers then consume, a behavior that many anthropologists suggest originated millions of years ago when early hominins began doing so across the savannas of Africa's Great Rift Valley. More recently, pastoralists and transhumant populations (i.e., seasonally moving populations of pastoralists and their herds) "turned the ecological table" on this symbiotic relationship when they began concentrating large flocks and herds of domesticated ungulates that vultures were attracted to and depended on as predictable sources of carrion.

Although it is unknown when raptors first began to live in human settlements, in all likelihood it happened early in our history. Primitive encampments that included refuse almost certainly attracted vultures and other scavenging birds of prey. This would have been especially true for smaller raptors, which were more likely than larger species to have been accommodated and not persecuted by humans.

More than most groups of birds, raptors have captured humanity's...