the Pigeon Paradox

Authors: Rob R. Dunn, Michael Gavin, Monica C. Sanchez and Jen Solomon

Why the global conservation of nature depends on

pigeons and other pests (pdf)

The News of the Paradox

Cornell Ornithology Lab
Columbidae.org
New York City Wildlife Alliance
The Bat Segundo Show
In Superdove, Courtney Humphries writes about the Pigeon Paradox in the context of the complex and wonderful story of pigeons.
One by One (an article by Nick Paumgarten in the New Yorker about Marko Pecaravic's work on Manhattan's median ants).
If people, viewed from a great height, look like ants, do ants, viewed at close range, look like people? Of course not. Ants have six legs, compound eyes, no lungs, and impossibly narrow waists, and they tend to hang around with aphids and mealybugs. Still, behavioral similarities make them excellent analogues. Ants, like humans, are into career specialization, livestock herding, engineering, climate control, in-flight sex, and war; for them, as for us, free will may or may not be an illusion. As for whether ants look to humans for insight into themselves, science has no answer. A few years ago, Marko Pecarevic, a Croatian graduate student studying conservation biology at Columbia University, met with his adviser, the urban ecologist James Danoff-Burg, to come up with a subject for his master’s thesis. Danoff-Burg had some data on ants in city parks and wondered if Pecarevic wanted to work on that. Pecarevic thought not. But afterward, crossing Broadway, he saw ants crawling around a garbage bin on one of the avenue’s medians. Medians! As habitats, the planted medians of Broadway were ubiquitous but overlooked, suitably biodiverse but extraordinarily distressed. For someone interested, as Pecarevic was, in the ecology of heavily compromised urban environments, medians were like remote, unexplored island chains—a Galápagos in Manhattan. He decided to be their Darwin. Employing Google Earth (forgive him, he’s from Zagreb), he chose three median-rich stretches—Park Avenue, the West Side Highway, and Broadway—then made himself an official-looking ID, dressed in parkish green, and started collecting ants, travelling the city with a duffelbag of garden tools and Evian bottles filled with antifreeze. No one bothered him. On a recent afternoon, Pecarevic, a trim, wry thirty-two-year-old, went out on a survey of his medians. For demonstration purposes, he had cadged a plastic cup from a coffeeshop, and pocketed a spoon. He carried, as he always does, an aspirator, a plastic tube that he uses to collect ants. He inhales them, alive, into a chamber. “Sometimes, when you suck up ants, they’re not happy about it,” he said. “If you blow cigarette smoke on them, they calm down.” Really, this was a farewell tour—he was returning to Zagreb the next day, to pursue a doc-torate. His thesis (“Ant Diversity and Abundance Increase with Increasing Plant Complexity and Amount of Garbage Bins in New York City Street Medians”) was done, and he was bequeathing to New York some interesting conclusions about its ants. For example,.... (read on)

We are faced with the potential extinction of thousands of species and with radical changes to many of theworld’s ecosystems in the next 50–100 years. Paradoxically, conservation may increasingly depend on the ability of people in cities to maintain a connection with nature. We term this concept the “pigeon paradox” because, if we are right, under the status quo a great deal of future conservation will rely in part on our interactions with urban ecosystems and the organisms, including non-natives such as feral pigeons (e.g., Columba livia), that call them home. The paradox lies in the dependence of conservation action worldwide on peoples’ direct experiences with urban nature. Whereas the importance of urban conservation to urban populations and species has been highlighted (e.g., Miller & Hobbs 2002), the links between urban nature and conservation outside cities are poorly appreciated but may be at the heart of future conservation action. The pigeon paradox is based on three simple assertions: (1) current conservation action is insufficient, (2) people are more likely to take conservation action when they have direct experiences in the natural world, and (3) as human populations (and hence sources of conservation action) shift to cities, humans will primarily experience nature through contact with urban nature. If these assertions are supported, future incentive for conservation will depend increasingly upon people’s interactions with urban ecosystems.

Current Conservation Action Is Insufficient

Our most basic assertion is that current conservation action is insufficient and that future conservation will depend on more support (both financial and political) than currently present. By one estimate the need for conservation funding outweighs current spending by $2.3 billion annually ( James et al. 2001). In addition, the gap between scientific evidence and political action (e.g., climate-change policy in the United States) points to the need for more political pressure to ensure conservation action in the future. This political pressure can come from conservation-conscious voters, but a 2005 survey found that only 22% of U.S. voters based their votes in federal, state, and local elections on environmental issues (Hart & McInturff 2005).

People Are More Likely to Conserve Nature When They Have Direct Experiences in the Natural World

People with more exposure to nature are more interested in conserving it. Although interactions with nature are not the only route to interest in conservation (e.g., Kollmuss & Agyeman 2002), they are clearly an important and arguably necessary condition. For example, Chawla (1998, 1999) suggests that an individual’s environmental sensitivity, which she defines as “a predisposition to take an interest in learning about the environment, feeling concern for it, and acting to conserve it,” is based on “formative experiences” with nature.

Direct experience with the natural world, especially during childhood, appears to be the most important source of environmental sensitivity (Tanner 1980; Chawla 1999 and references therein). Those who are active in conserving the environment most often cite childhood experiences in the natural world as critical antecedents to their later environmental actions (Chawla 1998). Although a suite of variables, including education, socioeconomic status, culture, motivation, awareness, attitudes, values, and ecological knowledge, must interact to ultimately determine an individual’s conservation action, direct experience with nature appears to be a prerequisite for those involved in environmental action. Without the foundation of experiences with nature, future action seems less likely. If we hope to nurture environmental leaders and encourage more conservation action (more proconservation votes and donors), we need to ensure that children have access to nature.

As Human Populations (and Hence Sources of Conservation Action) Shift to Cities, Humans Will Only Experience Nature through Contact with Urban Species

An increasing majority of the world’s people live in cities (UN 2001).We therefore suspect that a majority of people in the world have never seen in person any organisms or habitat that cannot be found in cities. If the majority of people, however, and thus future environmental leaders, votes, and financial resources reside in urban areas, then the future of conservation depends on urban people’s ability to experience nature. In many cities of the world, this currently means interacting most often with ecosystems that have been drastically altered by human activity. Many ecological processes and native species can persist in cities. People living in cities can still interact with native species and see “natural” ecological processes. Numerically, however, the majority of interactions between humans and nature in cities are likely to be with organisms and habitats with negative cultural connotations. The most visible aspects of urban landscapes are often non-native species such as pigeons, roaches, House Sparrows (Passer domesticus), and rats. If the potential for a person to undertake proenvironmental action (whether it is in the form of donations, votes, or a new career) depends on direct environmental experience, than we, as conservationists, cannot afford to write off urban ecosystems and species.

Consequences and Conclusions

If our assertions are correct, the future of thousands of species and many ecosystems depends on urbanites’ interaction with urban nature. If the fate of nature depends on our relationship to urban nature, all is not lost, but we do need to consider more carefully how we manage, conserve, and interact with urban nature. Although our emphases on restoration and environmental access are not new, we think the realization that urban conservation has large implications for global conservation is new. We propose three major courses of action in response to the pigeon paradox: restoration of urban ecosystems, improved access to urban nature, and a careful consideration of the costs and benefits linked to how we portray non-native and so-called pestiferous urban species. For us, the most satisfying solution to the pigeon paradox would be to restore as many native species and habitats in cities as possible, so as to allow people to connect with native ecosystems. The possibilities for restoring diverse ecological communities in cities are great and represent an active area of research (Rosenzweig 2003). Many projects aimed at ecological restoration in cities are already underway, and these vary in scale and scope from wetland restoration, such as the work in the Hackensack Meadowlands in New Jersey, to species reintroduction efforts, such as those by New York City’s Department of Parks and Recreation’s Project X, which has released native painted turtles (Chrysemys picta) and Screech Owls (Otus asio) into Central Park (see Rosenzweig 2003 for other examples). At their most ambitious, urban restoration projects can actually succeed in managing for rare species in urban settings, but at the very least such projects can restore more diverse ecosystems than those represented by sidewalk cracks and abandoned lots. When citizens are directly involved in such restoration, these projects have the additional benefit of allowing individuals to not only interact with nature, but also appreciate the value of intact ecosystems and native species in wild settings. Few experiences can be as valuable in allowing an appreciation of nature as restoration programs that involve local citizens. A native bird in the hand is worth thousands on the Discovery channel.

Even where diverse green spaces are present in urban areas, they are often clumped in wealthy neighborhoods (e.g., Iverson & Cook 2000). Considering the potential link between direct environmental experience and conservation action, inequitable distribution of urban nature may contribute to the incredibly low numbers of minorities in environmental leadership positions. Restoring green areas to poor areas need not be expensive and can add social and ecological benefits beyond engendering positive relationships with nature. If we want to attract a broader base of support, conservationists need to place more emphasis on the quantity and distribution of urban green space. Urban restoration, more urban parks, greenways programs, and community gardens can all bring the natural world to a larger portion of the urban population. More equitable access to high-quality zoos and museums can reinforce and expand on these interactions. Although poor urbanites do not donate most of the money for conservation, they can vote. Because close to half of all people on Earth might be classed as poor and urban, this vote is not inconsequential. If more than half of the people on earth find no reason to care about nature, we are in trouble.

And what of those regions, poor or rich, where we are unable to restore habitats, either economically or practically? Here the options are complex and few. The status quo approach is to categorize many of these habitats (be they the cracks between sidewalks, underpasses, or back alleys) and the pest and introduced species that inhabit them as scary, unhealthy, and bad, and then to hope citizens can find interactions with native species elsewhere. For many of these species, negative categorizations may be useful when imposed in more natural settings, but the utility of these species should be context dependent. Is it worth encouraging citizens to interact, appreciate, and watch the species they can find in cities, even if they are non-native?We think it might be, but admit there are costs to embracing introduced species in urban circumstances, even where those species seem to cause little ecological damage.

One cost is that we could embrace these species at the expense of our ability to control them elsewhere. One way around the potential costs might be to encourage appreciation of the native species sometimes thought of as pests (e.g., raccoons, squirrels, crows, and moles) and those non-native species that have a known low environmental cost. The initial focus could be on those species with relatively neutral cultural values, such as pigeons. Most of the pigeon species in cities, including Rock Doves (Columba livia), have relatively few negative impacts on native ecosystems. Rock Doves are nowan integral part of many urban ecosystems and together with European Starlings (Sturnus vulgaris), and Morning Doves (Zenaida macroura) constitute most of the diet of some native raptors now found in these ecosystems (e.g., Roth & Lima 2003). Furthermore, and more to the point of our thesis, the complex coos of doves can be soothing and the lives of doves can open the door into a broader interest in wild nature. What we must now ask is how estimates of the costs of abundant urban species stack up against the complex values of our interactions with them, including their value for global conservation. Although most ecosystems and species will not be saved in cities, their conservation may depend on the votes, donations, and future environmental leadership of people in cities; so, in the end, a great deal depends on urban nature. The urban jungle, with its many non-native species, may well be the breeding ground for future environmental action. What that urban jungle looks like, and how people interact with it, deserves more attention.

Acknowledgment

The authors thank N. Haddad, A. Leidner, A. Gove, G. Crutsinger, and S. Weaver for reading this manuscript.

Literature Cited

Chawla, L. 1998. Significant life experiences revisited: a review of research on sources of environmental sensitivity. The Journal of Environmental Education 29:11–21.

Chawla, L. 1999. Life paths into effective environmental action. The Journal of Environmental Education 31:15–26.

Hart, P., and B. McInturff. 2005. A presentation of key findings from a national survey of 800 likely voters. Nicholas Institute for Environmental Policy Solutions, Duke University, Durham, North Carolina. Available from http://www.nicholas.duke.edu/institute/projectssurvey. html (accessed April 2006).

Iverson, L. R., and E. A. Cook. 2000. Urban forest cover of the Chicago region and its relation to household density and income. Urban Ecosystems 4:105–124.

James, A., K. J. Gaston, and A. Balmford. 2001. Canwe afford to conserve biodiversity? BioScience 51:43–52. Kollmuss, A., and J. Agyeman. 2002. Mind the Gap: why do people act environmentally and what are the barriers to pro-environmental behavior? Environmental Education Research 8:239–260.

Miller, J. R., and R. J. Hobbs. 2002. Conservation where people live and work. Conservation Biology 16:330–337.

Roth, T. C., and S. L. Lima. 2003. Hunting behavior and diet of Cooper’s Hawks: an urban viewof the small-bird-in-winter paradigm. The Condor 105:474–483.

Rosenzweig, M. 2003. Win–win ecology: how the earth’s species can survive in the midst of the human enterprise. Oxford University Press, Oxford, United Kingdom. Tanner, T. 1980. Significant life experiences. The Journal of Environmental Education 4:399–417. UN (United Nations). 2001. World urbanization prospects: the 2001 revision. UN, New York