Road bias for deer density estimates at 2 national parks in Maryland

Abstract Estimating the population density of deer is an essential task for public agencies that plan a herd reduction. Distance sampling has been increasingly utilized to estimate population density, and is used by the National Park Service to estimate white‐tailed deer (Odocoileus virginianus) den...

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Main Authors: William J. McShea, Chad M. Stewart, Laura Kearns, Scott Bates
Format: Article
Language:English
Published: Wiley 2011-09-01
Series:Wildlife Society Bulletin
Subjects:
Online Access:https://doi.org/10.1002/wsb.53
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author William J. McShea
Chad M. Stewart
Laura Kearns
Scott Bates
author_facet William J. McShea
Chad M. Stewart
Laura Kearns
Scott Bates
author_sort William J. McShea
collection DOAJ
description Abstract Estimating the population density of deer is an essential task for public agencies that plan a herd reduction. Distance sampling has been increasingly utilized to estimate population density, and is used by the National Park Service to estimate white‐tailed deer (Odocoileus virginianus) densities throughout the eastern United States. Many of these surveys are conducted along public roads due to limited resources and accessibility, which may violate a critical assumption of distance sampling and potentially introduce sampling bias. We used infrared cameras to confirm deer activity with respect to survey roads at 2 national parks in Maryland, USA (Catoctin National Park and Antietam National Historic Battlefield), during 2005 and 2006 and compared results with the predicted distributions. The number of deer observed during road surveys declined with distance intervals at Catoctin, but there was a similar amount of deer activity at each distance interval. At Antietam, survey observations maintained a constant level of activity beyond 200 m from the survey route, while deer activity was inconsistent between distance intervals. The mean number of deer photographs/day/sample point did vary significantly across distance intervals from the survey route at Antietam, but not at Catoctin. In Antietam, the uneven distribution of agricultural fields and public roads were significant predictors of deer activity detected during the camera surveys. At Catoctin, the fit of the detection function was improved by expanding the first distance interval. Although density estimation using DISTANCE can account for most sources of error introduced by use of public roads, our data indicate bias is likely to occur in landscapes with high road densities and long sight distances. © 2011 The Wildlife Society.
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spelling doaj-art-ae9c16f90bca4b9c82d74f4d88d605e92024-12-16T11:20:37ZengWileyWildlife Society Bulletin2328-55402011-09-0135317718410.1002/wsb.53Road bias for deer density estimates at 2 national parks in MarylandWilliam J. McShea0Chad M. Stewart1Laura Kearns2Scott Bates3Smithsonian's Conservation Biology Institute, 1500 Remount Road, Front Royal, VA 22630, USASmithsonian's Conservation Biology Institute, 1500 Remount Road, Front Royal, VA 22630, USASmithsonian's Conservation Biology Institute, 1500 Remount Road, Front Royal, VA 22630, USAUrban Ecology Center, National Capital Region, National Park Service, Washington, D.C., USAAbstract Estimating the population density of deer is an essential task for public agencies that plan a herd reduction. Distance sampling has been increasingly utilized to estimate population density, and is used by the National Park Service to estimate white‐tailed deer (Odocoileus virginianus) densities throughout the eastern United States. Many of these surveys are conducted along public roads due to limited resources and accessibility, which may violate a critical assumption of distance sampling and potentially introduce sampling bias. We used infrared cameras to confirm deer activity with respect to survey roads at 2 national parks in Maryland, USA (Catoctin National Park and Antietam National Historic Battlefield), during 2005 and 2006 and compared results with the predicted distributions. The number of deer observed during road surveys declined with distance intervals at Catoctin, but there was a similar amount of deer activity at each distance interval. At Antietam, survey observations maintained a constant level of activity beyond 200 m from the survey route, while deer activity was inconsistent between distance intervals. The mean number of deer photographs/day/sample point did vary significantly across distance intervals from the survey route at Antietam, but not at Catoctin. In Antietam, the uneven distribution of agricultural fields and public roads were significant predictors of deer activity detected during the camera surveys. At Catoctin, the fit of the detection function was improved by expanding the first distance interval. Although density estimation using DISTANCE can account for most sources of error introduced by use of public roads, our data indicate bias is likely to occur in landscapes with high road densities and long sight distances. © 2011 The Wildlife Society.https://doi.org/10.1002/wsb.53density estimatordistance samplingMarylandOdocoileus virginianusroad surveysuburban deer
spellingShingle William J. McShea
Chad M. Stewart
Laura Kearns
Scott Bates
Road bias for deer density estimates at 2 national parks in Maryland
Wildlife Society Bulletin
density estimator
distance sampling
Maryland
Odocoileus virginianus
road survey
suburban deer
title Road bias for deer density estimates at 2 national parks in Maryland
title_full Road bias for deer density estimates at 2 national parks in Maryland
title_fullStr Road bias for deer density estimates at 2 national parks in Maryland
title_full_unstemmed Road bias for deer density estimates at 2 national parks in Maryland
title_short Road bias for deer density estimates at 2 national parks in Maryland
title_sort road bias for deer density estimates at 2 national parks in maryland
topic density estimator
distance sampling
Maryland
Odocoileus virginianus
road survey
suburban deer
url https://doi.org/10.1002/wsb.53
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AT laurakearns roadbiasfordeerdensityestimatesat2nationalparksinmaryland
AT scottbates roadbiasfordeerdensityestimatesat2nationalparksinmaryland