Counting roaring stags during the rut has been proposed as a means to assess deer population size and trends but few, if any, attempts have been made to evaluate the reliability of this technique. By means of a commonly used field protocol, we assessed to what extent relative abundance estimates of red deer (Cervus elaphus) based on roaring-stag counts in the northern Apennines (Italy) were susceptible to exogenous and unpredictable sources of variability. By using up to 26 simultaneous observers in an area of 5218 ha, we estimated densities from 0.45 to 0.61 roaring stags per 100 ha in 3 consecutive years (1992-94), corresponding to annual changes in the number of counted roaring stags ranging from -21% to +35.7%. However, only in two of the three years were seasonal trends and peaks in roaring activity apparent, and timing of the survey was not always synchronous with the roaring peak. In addition, annual and nocturnal variation in roaring activity, and weather conditions during the survey, might have influenced the counts to some extent, probably determining high Type I and Type II error rates. We contend that additional sources of error, associated with unknown demographic and ecological settings, may further increase unreliability of the technique when it is used to estimate absolute density of red deer populations. We conclude by emphasising that managers should not use this method for population monitoring unless they can prove it can yield reliable results.

Pitfalls in using counts of roaring stags to index red deer (Cervus elaphus) population size / Ciucci, Paolo; Gianluca, Catullo; Boitani, Luigi. - In: WILDLIFE RESEARCH. - ISSN 1035-3712. - STAMPA. - 36:2(2009), pp. 126-133. [10.1071/wr07121]

Pitfalls in using counts of roaring stags to index red deer (Cervus elaphus) population size

CIUCCI, Paolo;BOITANI, Luigi
2009

Abstract

Counting roaring stags during the rut has been proposed as a means to assess deer population size and trends but few, if any, attempts have been made to evaluate the reliability of this technique. By means of a commonly used field protocol, we assessed to what extent relative abundance estimates of red deer (Cervus elaphus) based on roaring-stag counts in the northern Apennines (Italy) were susceptible to exogenous and unpredictable sources of variability. By using up to 26 simultaneous observers in an area of 5218 ha, we estimated densities from 0.45 to 0.61 roaring stags per 100 ha in 3 consecutive years (1992-94), corresponding to annual changes in the number of counted roaring stags ranging from -21% to +35.7%. However, only in two of the three years were seasonal trends and peaks in roaring activity apparent, and timing of the survey was not always synchronous with the roaring peak. In addition, annual and nocturnal variation in roaring activity, and weather conditions during the survey, might have influenced the counts to some extent, probably determining high Type I and Type II error rates. We contend that additional sources of error, associated with unknown demographic and ecological settings, may further increase unreliability of the technique when it is used to estimate absolute density of red deer populations. We conclude by emphasising that managers should not use this method for population monitoring unless they can prove it can yield reliable results.
2009
census; cervus elaphus; population abundance; population monitoring; red deer; roaring stags
01 Pubblicazione su rivista::01a Articolo in rivista
Pitfalls in using counts of roaring stags to index red deer (Cervus elaphus) population size / Ciucci, Paolo; Gianluca, Catullo; Boitani, Luigi. - In: WILDLIFE RESEARCH. - ISSN 1035-3712. - STAMPA. - 36:2(2009), pp. 126-133. [10.1071/wr07121]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/105137
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