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Hydrological assessment of Moosehorn National Wildlife Refuge Impoundments and vegetation and wildlife response to impoundment management


June 2000 - December 2004


We assessed changes in vegetative structure of 49 impoundments at Moosehorn National Wildlife Refuge (MNWR), Maine, USA, between the periods 1984-1985 to 2002 with a multivariate, adaptive approach that may be useful in a variety of wetland and other habitat management situations. We used Mahalanobis Distance (MD) analysis to classify the refuge’s wetlands as poor or good waterbird habitat based on 5 variables (i.e., percent emergent vegetation, percent shrub, percent open water, relative richness of vegetative types, and an interspersion juxtaposition index that measures adjacency of vegetation patches). Mahalanobis Distance is a multivariate statistic that examines whether a particular data point is an outlier or a member of a data cluster while accounting for correlations among inputs. For each wetland, we used MD analysis to quantify a distance from a reference condition defined a priori by habitat conditions measured in MNWR wetlands used by waterbirds. Twenty-five wetlands declined in quality between the two periods, whereas 23 wetlands improved. We identified specific wetland characteristics that may be modified to improve habitat conditions for waterbirds. The MD analysis seems ideal for instituting an adaptive wetland management approach because metrics can be easily added or removed, ranges of target habitat conditions can be defined by field-collected data, and the analysis can identify priorities for single or multiple management objectives.

Research Products and Activities

Peer Reviewed Publications

  • Hierl, L., C. S. Loftin, J. R. Longcore, D. G. McAuley, and D. Urban. 2007. A Multivariate Assessment of Changes in Wetland Habitat Conditions for Waterbirds at Moosehorn National Wildlife Refuge, Maine, USA. Wetlands 27(1): 141-152.

Technical Publications

  • Hierl, L., C.S. Loftin, J. Longcore, and D. McAuley. 2003. A multivariate assessment of wetland habitat conditions in Moosehorn National Wildlife Refuge, Maine. Final project report for RWO 43 Hydrological assessment of Moosehorn National Wildlife Refuge Impoundments, 163 pp.


  • Hierl, L., C.S. Loftin, J.R. Longcore, D.G. McAuley, and D. Urban. A Multivariate Assessment of Changes in Wetland Habitat Conditions for Waterbirds at Moosehorn National Wildlife Refuge, Maine, USA. Presentation at the New England Chapter of The Wildlife Society, Annual Workshop, 28 October 2005, Hadley, MA.
  • Hierl, L., C. Loftin, J. Longcore and D. Urban. 2006. A multivariate assessment of changes in wetland habitat for waterbirds at Moosehorn National Wildlife Refuge, Maine, USA. 21st Annual Symposium of the United States regional Chapter of the International Association of Landscape Ecologists, 28 March-1 April, San Diego, CA.

Current Staff

Federal Staff: 2

Masters Students: 4

Phd Students: 5

Post Docs: 1

University Staff: 11

5 Year Summary

Students graduated: 24

Scientific Publications: 52

Presentations: 282



Funding Agencies

  • Cooperative Research Unit Program
  • University of Maine


Maine Cooperative Fish and Wildlife Research Unit Cooperators

  1. Maine Department of Inland Fisheries and Wildlife
  2. U.S. Fish and Wildlife Service
  3. U.S. Geological Survey
  4. University of Maine
  5. Wildlife Management Institute