Sign surveys for estimating trend of a remnant brown bear Ursus arctos population in northern Spain

被引:15
作者
Clevenger, Anthony P. [1 ,2 ]
Purroy, Francisco J. [2 ]
机构
[1] Univ Tennessee, Dept Forestry Wildlife & Fisheries, Knoxville, TN 37901 USA
[2] Univ Leon, Dept Biol Anim, E-24071 Leon, Spain
关键词
brown bear; monitoring; population trend; sign survey; Spain; statistical power; Ursus arctos;
D O I
10.2981/wlb.1996.031
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
Clevenger, P.A. & Purroy F.J. 1996: Sign surveys for estimating trend of a remnant brown bear Ursus arctos population in northern Spain. - Wildl. Biol. 2: 275-281. Brown bears Ursus arctos in Spain's Cantabrian Mountains are continuing to decline in numbers despite their protected status. Recovery plans for this population stress the need for monitoring of occupied habitat using non-intrusive methods. A population monitoring program to estimate bear abundance indices by quantifying tracks and scats (sign surveys) along a network of survey routes was designed. Each route was divided into consecutive 1.6-km segments, which comprised the basic sampling unit, and were assumed to provide independent observations. During a 3-year pilot study surveys were run twice per year, totaling 70 routes, including 950 segments, and covering over 1,500 km annually. Averages of 0.06 sign per segment were observed; only 4% of the segments had sign. It is concluded that the present sampling scheme does not provide enough statistical power to accurately detect significant declines in population level. The difficulties of monitoring trends of low density populations using surveys are recognized. However, by increasing the sampling intensity, more reliable information and greater precision of the population trend estimate should be obtainable. Thus, a future monitoring strategy should be based on increasing sampling intensity and closely monitoring bear distribution and occurrence.
引用
收藏
页码:275 / 281
页数:7
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