Population dynamics and survival of an endangered wallaby: A comparison of four methods

Fisher, Diana O., Hoyle, Simon D. and Blomberg, Simon P. (2000) Population dynamics and survival of an endangered wallaby: A comparison of four methods. Ecological Applications, 10 3: 901-910. doi:10.2307/2641054

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Author Fisher, Diana O.
Hoyle, Simon D.
Blomberg, Simon P.
Title Population dynamics and survival of an endangered wallaby: A comparison of four methods
Journal name Ecological Applications   Check publisher's open access policy
ISSN 1051-0761
Publication date 2000-06
Sub-type Article (original research)
DOI 10.2307/2641054
Open Access Status File (Publisher version)
Volume 10
Issue 3
Start page 901
End page 910
Total pages 10
Editor Louis F. Pitelka
Place of publication Washington, DC, United States
Publisher Ecological Society of America
Collection year 2000
Language eng
Formatted abstract
The bridled nailtail wallaby Onychogalea fraenata is a critically endangered marsupial, now restricted to a single locality in central Queensland, eastern Australia. Its small size and its nocturnal, solitary, and cryptic behavior present problems for monitoring of population dynamics. The population apparently declined during a major drought between 1991 and 1995, when juvenile survival was low. We carried out a detailed demographic analysis from 1994 to 1997 in order to estimate survival and abundance in two different habitats, using mark–recapture, mark–resight, radio-tagging, and line-transect methods. The finite rate of increase (λ) and its sensitivity to changes in survival and reproduction of each age class were also calculated using a matrix population projection model. We then assessed biases and the value of each method for management. For data other than those based on radio-tagging data, population size and survival estimates were negatively biased and had large confidence limits. Line-transect estimates were likely to be the least biased. The reasons were that probabilities of capture and sighting varied among sexes, sites, and times; habitat use varied according to vegetation conditions; and the populations were small. Despite this, all methods indicated an increasing population size. The projected value of λ based on radio-tagging data was most sensitive to adult survival. Vegetation conditions improved throughout the study after an initial drought, and the mean projected intrinsic rate of increase was 28% per year. We conclude that management should aim to increase adult survival via predator control and that line-transect estimation is the most appropriate long-term monitoring method.
© 2000 by the Ecological Society of America
Keyword Ecology
Age-specific survival
Bridled nailtail wallaby
Life history
Line transect
Matrix model
Onychogalea fraenata
Population dynamics
Stage-structured populations
Northern spotted owl
Model selection
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Biological Sciences Publications
Ecology Centre Publications
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Citation counts: TR Web of Science Citation Count  Cited 39 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 10 Jun 2008, 11:20:57 EST