@article {1841,
	title = {Presence-absence versus abundance data for monitoring threatened species},
	journal = {Conservation Biology},
	volume = {20},
	number = {6},
	year = {2006},
	pages = {1679-1687},
	abstract = {Effective detection of population trend is crucial for managing threatened species. Little theory exists, however, to assist managers in choosing the most cost-effective monitoring techniques for diagnosing trend. We present a framework for determining the optimal monitoring strategy by simulating a manager collecting data on a declining species, the Chestnut-rumped Hylacola (Hylacola pyrrhopygia parkeri), to determine whether the species should be listed under the IUCN ( World Conservation Union) Red List. We compared the efficiencies of two strategies for detecting trend, abundance, and presence{\textendash}absence surveys, under financial constraints. One might expect the abundance surveys to be superior under all circumstances because more information is collected at each site. Nevertheless, the presence{\textendash}absence data can be collected at more sites because the surveyor is not obliged to spend a fixed amount of time at each site. The optimal strategy for monitoring was very dependent on the budget available. Under some circumstances, presence{\textendash}absence surveys outperformed abundance surveys for diagnosing the IUCN Red List categories cost-effectively. Abundance surveys were best if the species was expected to be recorded more than 16 times/year; otherwise, presence{\textendash}absence surveys were best. The relationship between the strategies we investigated is likely to be relevant for many comparisons of presence{\textendash}absence or abundance data. Managers of any cryptic or low-density species who hope to maximize their success of estimating trend should find an application for our results.},
	keywords = {Chestnut-rumped Hylacola, economics, Hylacola pyrrhopygia parkeri, IUCN Red List, occupancy data, optimal monitoring, species detectability, threatened species management},
	author = {Joseph, Liana N. and Field, Scott A. and Wilcox, Chris and Possingham, Hugh P.}
}
