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Optimizing Presence–Absence Surveys For Detecting Population Trends

In English

Författare

  • J R Rhodes
  • A J Tyre
  • Niclas Jonzén
  • C A McAlpine
  • H P Possingham

Summary, in English

Presence–absence surveys are a commonly used method for monitoring broad-scale changes in wildlife distributions. However, the lack of power of these surveys for detecting population trends is problematic for their application in wildlife management. Options for improving power include increasing the sampling effort or arbitrarily relaxing the type I error rate. We present an alternative, whereby targeted sampling of particular habitats in the landscape using information from a habitat model increases power. The advantage of this approach is that it does not require a trade-off with either cost or the Pr{type I error} to achieve greater power. We use a demographic model of koala (Phascolarctos cinereus) population dynamics and simulations of the monitoring process to estimate the power to detect a trend in occupancy for a range of strategies, thereby demonstrating that targeting particular habitat qualities can improve power substantially. If the objective is to detect a decline in occupancy, the optimal strategy is to sample high-quality habitats. Alternatively, if the objective is to detect an increase in occupancy, the optimal strategy is to sample intermediate-quality habitats. The strategies with the highest power remained the same under a range of parameter assumptions, although observation error had a strong influence on the optimal strategy. Our approach specifically applies to monitoring for detecting long-term trends in occupancy or abundance. This is a common and important monitoring objective for wildlife managers, and we provide guidelines for more effectively achieving it.

Publiceringsår

2006

Språk

Engelska

Sidor

8-18

Publikation/Tidskrift/Serie

Journal of Wildlife Management

Volym

70

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

The Wildlife Society

Ämne

  • Biological Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0022-541X