Ecological Correlates and Conservation Implications of Overestimating Species Geographic Ranges

Species range maps based on extents of occurrence (EOO maps) have become the basis for many analyses in broad-scale ecology and conservation. Nevertheless, EOO maps are usually highly interpolated and overestimate small-scale occurrence, which may bias research outcomes. We evaluated geographical range overestimation and its potential ecological causes for 1158 bird species by quantifying EOO map occurrence across 4040 well-studied survey locations in Australia, North America, and southern Africa at the scale of 80-742 km2. Most species occurred in only 40-70% of the range indicated by their EOO maps. The observed proportional range overestimation affected the range-size frequency distribution, indicating that species are more range-restricted than suggested by EOO maps. The EOO maps most strongly overestimated the distribution of narrow-ranging species and ecological specialists with narrow diet and habitat breadth. These relationships support basic ecological predictions about the relationship between niche breadth and the fine-scale occurrence of species. Consequently, at-risk species were subject to particularly high proportional range overestimation, on average 62% compared with 37% of nonthreatened species. These trends affect broad-scale ecological analyses and species conservation assessments, which will benefit from a careful consideration of potential biases introduced by range overestimation.

[1]  Robert D. Holt,et al.  On the evolutionary ecology of species' ranges , 2003 .

[2]  B. Menge,et al.  Scale, Environment, and Trophic Status: The Context Dependency of Community Saturation in Rocky Intertidal Communities , 2006, The American Naturalist.

[3]  J. D. Hoyo,et al.  Handbook of the Birds of the World , 2010 .

[4]  W. Jetz,et al.  Type and spatial structure of distribution data and the perceived determinants of geographical gradients in ecology : the species richness of African birds , 2007 .

[5]  Richard Fox,et al.  Spatial patterns in species distributions reveal biodiversity change , 2004, Nature.

[6]  Ethan P. White,et al.  Ecological correlates of geographical range occupancy in North American birds , 2007 .

[7]  A. Stattersfield,et al.  Endemic Bird Areas of the World: Priorities for Biodiversity Conservation , 1998 .

[8]  Burt L. Monroe,et al.  A Supplement To Distribution And Taxonomy Of Birds Of The World , 1952 .

[9]  Richard Field,et al.  ENERGY, WATER, AND BROAD‐SCALE GEOGRAPHIC PATTERNS OF SPECIES RICHNESS , 2003 .

[10]  A. Dobson,et al.  Projected Impacts of Climate and Land-Use Change on the Global Diversity of Birds , 2007, PLoS biology.

[11]  P. C. Mathias,et al.  Sensitivity of macroecological patterns of South American parrots to differences in data sources , 2004 .

[12]  Kate E. Jones,et al.  Multiple Causes of High Extinction Risk in Large Mammal Species , 2005, Science.

[13]  L. Hannah,et al.  The View from the Cape: Extinction Risk, Protected Areas, and Climate Change , 2005 .

[14]  Jon E. Ahlquist,et al.  Phylogeny and Classification of the Birds: A Study in Molecular Evolution , 1991 .

[15]  Catherine H. Graham,et al.  A comparison of methods for mapping species ranges and species richness , 2006 .

[16]  Paul R. Ehrlich,et al.  Ecosystem consequences of bird declines , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[17]  Robert P Freckleton,et al.  Distributions of Habitat Suitability and the Abundance‐Occupancy Relationship , 2005, The American Naturalist.

[18]  A. Stattersfield,et al.  Threatened birds of the world : the official source for birds on the IUCN Red List , 2000 .

[19]  K. Simpson,et al.  Birds of Australia , 2000 .

[20]  Robert P. Freckleton,et al.  Large‐scale population dynamics, abundance–occupancy relationships and the scaling from local to regional population size , 2005 .

[21]  W. Jetz,et al.  Effects of species’ ecology on the accuracy of distribution models , 2007 .

[22]  E. K. Urban,et al.  The Birds of Africa , 1982 .

[23]  Michael J. O. Pocock,et al.  Coherence and discontinuity in the scaling of specie's distribution patterns , 2004, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[24]  J. L. Gittleman,et al.  Predicting extinction risk in declining species , 2000, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[25]  G. Daily,et al.  Range Occupancy and Endangerment: A Test with a Butterfly Community , 2007 .

[26]  C. Rahbek,et al.  Geographic Range Size and Determinants of Avian Species Richness , 2002, Science.

[27]  M. Pagel,et al.  Phylogenetic Analysis and Comparative Data: A Test and Review of Evidence , 2002, The American Naturalist.

[28]  H. Resit Akçakaya,et al.  Value of the IUCN Red List , 2003 .

[29]  Ethan P. White,et al.  Disparity between range map- and survey-based analyses of species richness: patterns, processes and implications , 2005 .

[30]  G. C. Stevens.  The Latitudinal Gradient in Geographical Range: How so Many Species Coexist in the Tropics , 1989, The American Naturalist.

[31]  J. Dunning,et al.  CRC Handbook of Avian Body Masses , 2007 .

[32]  T. F. Hansen,et al.  Phylogenies and the Comparative Method: A General Approach to Incorporating Phylogenetic Information into the Analysis of Interspecific Data , 1997, The American Naturalist.

[33]  Christopher N. Johnson,et al.  Niche breadth and geographical range: ecological compensation for geographical rarity in rainforest frogs , 2006, Biology Letters.

[34]  H. Resit Akçakaya,et al.  Use and misuse of the IUCN Red List Criteria in projecting climate change impacts on biodiversity , 2006 .

[35]  C. Rahbek,et al.  Conservation conflicts across Africa. , 2001, Science.

[36]  V. Parker,et al.  The atlas of southern African birds , 1997 .

[37]  Jorge Soberón,et al.  Global Mammal Conservation: What Must We Manage? , 2005, Science.

[38]  Robert K. Colwell,et al.  On the Measurement of Niche Breadth and Overlap. , 1971, Ecology.

[39]  R. G. Davies,et al.  Global hotspots of species richness are not congruent with endemism or threat , 2005, Nature.

[40]  K. Gaston,et al.  Species-range-size distributions: patterns, mechanisms and implications. , 1996, Trends in ecology & evolution.

[41]  Walter Jetz,et al.  Species richness, hotspots, and the scale dependence of range maps in ecology and conservation , 2007, Proceedings of the National Academy of Sciences.

[42]  J. Lawton,et al.  Range, population abundance and conservation. , 1993, Trends in ecology & evolution.

[43]  H. Resit Akçakaya,et al.  Measuring Global Trends in the Status of Biodiversity: Red List Indices for Birds , 2004, PLoS biology.

[44]  J. Grinnell.  The Niche-Relationships of the California Thrasher , 1917 .

[45]  M. Araújo,et al.  Species richness, area and climate correlates , 2006 .

[46]  Neil D. Burgess,et al.  Bird Census Techniques , 1992 .

[47]  William E. Kunin,et al.  Scale Dependency of Rarity, Extinction Risk, and Conservation Priority , 2003 .