E-Letter responses to:

reports: George Wittemyer, Paul Elsen, William T. Bean, A. Coleman O. Burton, and Justin S. Brashares Accelerated Human Population Growth at Protected Area Edges Science 2008; 321: 123-126 [Abstract] [Full text] [PDF]

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Published E-Letter responses:

Reply to J. Igoe et al. and L. P. Shoo's E-Letters

George Wittemyer, Paul Elsen, William T. Bean, A. Coleman O. Burton, Justin S. Brashares   (11 December 2008)

A Balance Between Protected Lands and Population Growth

Luke P. Shoo   (11 December 2008)

Lessons to Be Learned About Migration Around Protected Areas

James Igoe, Dan Brockington, Sara Randall, Katherine Scholfield   (11 December 2008)

Reply to J. Igoe et al. and L. P. Shoo's E-Letters 11 December 2008
George Wittemyer Department of Environmental Science, Policy and Management, University of California, Berkeley, USA, Paul Elsen, William T. Bean, A. Coleman O. Burton, Justin S. Brashares Respond to this E-Letter: Re: Reply to J. Igoe et al. and L. P. Shoo's E-Letters	J. Igoe et al. highlight issues important for gaining a broader understanding of the relationship between local people and protected areas (PAs), many of which we agree with and discussed in our original paper (1). Contrary to their primary claim that we disregarded the importance of perceived versus actual benefits, we specifically stated that the probable cause of immigration to PA borders is perceived benefits (p. 123 and 125). Because few data are available to allow a large scale evaluation of migrants' perceptions of PAs, we focused our analysis on quantitative metrics relating to conditions in and around our focal PAs [staff numbers, Global Environment Facility (GEF) spending, PA size]. The unprecedented urbanization observed throughout the developing world is most often attributed to the perception among migrants that economic opportunity awaits them in urban centers [e.g., (2)]. We contend that a similar perception of opportunity stemming from PA staffing, tourism, infrastructure and donor projects influences the attractiveness of PAs as settlement sites. As pointed out by Igoe et al., immigrants are unlikely to benefit from these activities equally, just as many immigrants attracted to the economic activities in urban areas may not meet their expectations of success. While assessing the degree to which these expectations are being met is beyond the scope of our analysis, we argue that opportunities related to PAs have made PA borders attractive to settlement and that this settlement will threaten the long term sustainability of these areas. Our study (1) presents a macro-scale analysis that offers insight into general trends occurring across 45 countries and two continents, and we recognize its limitations for identifying causal mechanisms. Because of this, we called for fine-scale case analyses to gain a more detailed understanding of the many factors driving human population change on PA borders (p. 124). Ignoring this call, Igoe et al. claim we exaggerate the mechanistic connections we present. For example, they purport the dollar amount invested by NGOs and the GEF is too low to cause migration. However, they do not mention the other major sources of revenue these PAs receive from tourism, commerce, and resource extraction as well as investment from domestic and foreign governments, though they do acknowledge that total productivity will affect the perception of PAs among potential immigrants. Igoe et al. propose that re-analysis of the spatial distribution of growth around PAs will offer insight into the attractants driving immigration to PA borders. This simplistic approach would not distinguish among the many attractants we hypothesize drive population change around PAs (p. 123, Table 1). Their primary claim that growth driven by access to enhanced ecosystem services will show spatial uniformity in PA buffers makes the faulty assumptions that (i) ecosystem services are homogeneously distributed within PAs, and (ii) access to markets, schools, dispensaries or other social support systems does not impact the distribution of people relying on ecosystem services. Such assumptions are not supported by the growing body of knowledge on ecosystem services [e.g., (3)]. We recognize the challenges implicit in understanding the mechanisms driving our results, and we have called for further, locally-based studies and more generally, a greater awareness of the causes and consequences of human migration to PA borders. By overlooking these calls, as well as the relevance and value of the broad patterns we highlight, Igoe et al. appear to miss the point of our study. Similarly, in his critique of our paper, L. P. Shoo raises points that were either considered in our study or are largely outside the scope of our work. While it is difficult to determine conclusively whether PAs were gazetted in response to human pressure or if the pressures impacting PAs emerged after their establishment, our analysis comparing PA buffer growth rates to growth rates in identical ecoregions neighboring the PAs suggests strongly that the rates we report are not a result of preexisting pressure on these landscapes. By controlling for ecological setting in our analyses, our results indicate that gaining access to a PA, and its associated economic development over time, is a major attractant for settlement. We have not compiled a historical database for the PAs considered in our study, but a cursory evaluation suggests many PAs, if not most, were purposely placed in areas where competing interests were relatively absent. Moreover, we focused our study on rural PAs (i.e. those with no large human settlements within 10 kilometers of their borders), thus these PAs were those least likely to be established in response to pressure from high human density. Contrary to Shoo's assertion, we do not claim that gazettement alone is the force that attracts immigration and settlement on PA edges. Instead, we suggest that such sites are increasingly perceived as attractive when economic investment is targeted over time in and around PAs, and where PAs serve as islands of natural resources and ecosystem services in otherwise depleted landscapes. If we believed that the mere act of gazettement could draw settlement, we would not expect to find the correlations between population growth and PA budgets, foreign investment, and job creation that comprise a significant portion of our paper. Unfortunately, looking at population growth before and after PA gazettement is problematic because many of the PAs in our study were under some sort of protective status prior to their formal designation as an IUCN (International Union for Conservation of Nature) category I or II protected area. Also, spatially explicit demographic data on continental scales are only available since 1960, thus limiting the scope of pre- and post-gazettement comparisons. With the greatest human population growth typically occurring in the latter half of the century, often in the 1970s to 90s for the countries we sampled, much of the immigration we report occurred after gazettement dates for the majority of PAs in our study. However, this is context specific and demographic history varies by region and PA. George Wittemyer, Paul Elsen, William T. Bean, A. Coleman O. Burton, Justin S. Brashares Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, USA. References 1. G. Wittemyer, P. Elsen, W. T. Bean, A. C. O. Burton, J. S. Brashares, Science 321, 123 (2008). 2. C. Rakodi, The Urban Challenge in Africa: Growth and Management of its Large Cities (United Nations University Press, New York, 1997). 3. K. M. A. Chan, M. R. Shaw, D. R. Cameron, E. C. Underwood, G. C. Daily, PLoS Biology 4, 2138 (2006).
A Balance Between Protected Lands and Population Growth 11 December 2008
Luke P. Shoo School of Marine and Tropical Biology, James Cook University, Townsville, Qld 4811, Australia Respond to this E-Letter: Re: A Balance Between Protected Lands and Population Growth	G. Wittemyer et al. (Reports, "Accelerated human population growth at protected area edges," 4 July 2008, p. 123) provide strong evidence that human population growth on the borders of protected areas is greater (nearly double) than average rural growth in African and Latin American countries. What is inferred, but not tested, is that the gazetting of protected areas is the initial trigger for population growth and accompanying deforestation. The authors conclude that the disparity in growth rates is driven by people actively immigrating to edges of established protected areas in response to improved social and economic opportunities. This deduction is important because it suggests that the establishment of protected areas may in fact "exacerbate the same anthropogenic threats to biodiversity it aims to alleviate." But what if protected areas themselves were preferentially established at locations already highly threatened by human population growth and deforestation? Certainly there are good reasons why this might be so. Areas of outstanding conservation importance coincide with dense human settlement and expanding populations in Africa and Latin America (1, 2). Protected areas are one of society's responses to threatening processes (3) but there are not sufficient resources to immediately protect all areas that are earmarked for conservation. A popular strategy to deal with this dilemma has been to prioritize conservation action toward areas that exhibit both high biodiversity value and high levels of threat (4). This "minimize short term loss" strategy has been a strong feature of "save-species" campaigns at least since the 1950s (5) and has evolved into sophisticated conservation planning tools applied to global and continental assessments (6–11). This means that ideas about prioritizing protected areas based on threat have clearly been contemporary with the establishment of protected areas considered by Wittemyer et al. (median gazette year = 1975, n = 306). The crucial question then is what comes first—protected areas or human population growth? To answer this we need to know what population and deforestation rates were doing before, as well as after protected areas were established. Unfortunately, Wittemyer et al. only considered growth rates since protected areas were established. Although the authors raise some important issues for future conservation planning, in the end we are left to wonder whether the interpretation of "cause and effect" would not be different if proper consideration was given to the chronology of events. Luke P. Shoo Centre for Tropical Biodiversity and Climate Change, School of Marine and Tropical Biology, James Cook University of North Queensland, Townsville, QLD 4811, Australia. References 1. L. L. Manne, T. M. Brooks, S. L. Pimm, Nature 399, 258 (1999). 2. A. Balmford et al., Science 291, 2616 (2001). 3. K. Wilson et al., Environ. Manage. 35, 527 (2005). 4. C. R. Margules, R. L. Pressey, Nature 405, 243 (2000). 5. N. Myers, The Environmentalist 3, 97 (1983). 6. R. L. Pressey, in National Parks and Protected Areas: Selection, Delimitation and Management J. J. Pigram, R. C. Sundell, Eds. (Univ. of New England, Centre for Water Policy Research, Armidale, Australia, 1997), pp. 337–357. 7. R. A. Mittermeier, N. Myers, J. B. Thomsen, G. A. B. d. Fonseca, S. Olivieri, Conserv. Biol. 12, 516 (1998). 8. E. Dinerstein, E. D. Wikramanayake, Conserv. Biol. 7, 53 (1993). 9. A. Balmford, A. Long, Nature 372, 623 (1994). 10. T. D. Sisk, A. E. Launer, K. R. Switky, P. R. Ehrlich, Bioscience 44, 592 (1994). 11. N. Myers, The Environmentalist 8, 187 (1988).
Lessons to Be Learned About Migration Around Protected Areas 11 December 2008
James Igoe Department of Anthropology, Dartmouth University, Hanover, NH 03755, USA, Dan Brockington, Sara Randall, Katherine Scholfield Respond to this E-Letter: Re: Lessons to Be Learned About Migration Around Protected Areas	G. Wittermeyer et al.'s intriguing paper (Reports, "Accelerated human population growth at protected area edges," 4 July 2008, p. 123) ignores long-standing lessons in development studies about migration and prosperity, weakening its contribution to understanding of the population dynamics around protected areas. Poverty caused by protected areas is unlikely to cause the depopulation that the authors suggest. The literature they cite refers to displacement in protected areas, not the wider landscape. Key studies emphasise the importance of understanding small-scale changes, and the concentration of misfortunes onto marginal groups (1). The authors also exaggerate the material benefits that protected areas bring. Their infant mortality data do not support their claim that protected areas "may be positive for localised rural development" (p. 125). The $2 billion Global Environment Facility funding they report over 15 years, or the $200 million we calculated that conservation NGOs spend annually in sub-Saharan Africa (2), simply cannot effect enough actual change to induce the large-scale movements they describe. The emphasis on actual benefits is concerning because it risks forgetting vital early lessons in development planning. Planners learned the hard way in the 1970s that perceived benefits are a more powerful explanatory variable of migration than actual opportunities. The impact of protected areas on well-being may be negligible, but this could be offset by the tantalizing prospects of tourist dollars and cosmopolitan connections. Even in the absence of international investment, tourists encourage immigration. Planners also learned that the prosperity of growth poles is poorly accessible to immigrants. Thus, even if protected areas do bring prosperity, we would still have to examine how it is distributed to see who precisely they benefit. Decadal census data are a coarse way of examining the distribution of prosperity, and the emigration and immigration of winners and losers of protected area policy. But one way forward would be to examine the distribution of growth around protected areas. If migrants are drawn to enhanced ecosystem services, as the authors suggest, then population growth around protected areas would display a relatively even distribution. But we predict the growth is uneven, affecting only small part of each protected area's periphery, as would result when people move to perceived opportunities in nascent centers. Any re-examination of these patterns requires a more sceptical approach to the apparently detailed African demographic data where, for example, decadal trend data are unavailable for the Democratic Republic of Congo (one census) or Madagascar (two censuses). Where the timing of censuses has been irregular (Mali), small-scale population changes may be confounded by seasonal movements (3). Frameworks to understand the impacts of protected areas on people are becoming increasingly sophisticated (4). We require similarly sophisticated spatial models to understand in what circumstances, and with what spatial patterns, protected areas might attract or repel people. James Igoe Department of Anthropology, Dartmouth University, Hanover, NH 03755, USA. Dan Brockington School of Environment and Development, University of Manchester, Manchester M13 9PL, UK. Sara Randall Department of Anthropology, University College London, London WC1E 6BT, UK. Katherine Scholfield School of Geography, Politics and Sociology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK. References 1. D. Brockington, Conservation and Society 2, 411 (2004). 2. K. Scholfield, D. Brockington, BWPI, University of Manchester (in press). 3. S. Randall, in Brass Tacks: Essays in Medical Demography, B. Zaba, J. Blacker, Eds. (Athlone Press, London, 2001), pp. 186–204. 4. M. B.Mascia, C.A. Claus, Conserv. Biol. (in press).