Estimating demographic parameters for a critically endangered marine species with frequent reproductive omission: Hawksbill turtles nesting at Varanus Island, Western Australia

Prince, Robert I. T. and Chaloupka, Milani (2012) Estimating demographic parameters for a critically endangered marine species with frequent reproductive omission: Hawksbill turtles nesting at Varanus Island, Western Australia. Marine Biology, 159 2: 355-363. doi:10.1007/s00227-011-1813-5


Author Prince, Robert I. T.
Chaloupka, Milani
Title Estimating demographic parameters for a critically endangered marine species with frequent reproductive omission: Hawksbill turtles nesting at Varanus Island, Western Australia
Journal name Marine Biology   Check publisher's open access policy
ISSN 0025-3162
1432-1793
Publication date 2012-02-01
Year available 2011
Sub-type Article (original research)
DOI 10.1007/s00227-011-1813-5
Volume 159
Issue 2
Start page 355
End page 363
Total pages 9
Place of publication Heidelberg, Germany
Publisher Springer
Collection year 2012
Language eng
Formatted abstract
The hawksbill marine turtle (Eretmochelys imbricata) is listed on the IUCN Red List as critically endangered but little is known about its demography to support robust diagnosis of population trends. Moreover, adult female hawksbills do not nest each year due to environmentally mediated physiological constraints and this skipped breeding behaviour presents a major challenge in data collection and for estimating demographic parameters from such data sets. We estimated demographic parameters such as survival and breeding probabilities for a major Indo-Pacific nesting hawksbill population using a capture-mark-recapture (CMR) study and a multistate open robust design statistical modelling approach, which accounts for breeding omission and the staggered arrival and departure of nesters during each season. Our study used CMR histories for 413 nesting hawksbills tagged on Varanus Island (Western Australia) over a 4-month sampling period each year for 20 austral summer nesting seasons between 1987 and 2007. The estimated annual survival probability for these nesting hawksbills was constant over the 20 years at ca. 0.947 (95% CI: 0.91–0.97), which is encouragingly high for a population associated with industry. The estimated annual conditional nesting (breeding) probability for female hawksbills that had skipped the previous nesting season was time-specific ranging from 0.07 to 0.29 (mean = 0.18, CV = 41.3%), which presumably reflects the interaction between turtle physiology and in-water habitat quality. The mean conditional probability of breeding again having skipped 2 prior consecutive nesting seasons was ca. 0.83 (95% CI: 0.73–0.89), indicating a high frequency of breeding season omission. The annual nesting probability for females that had nested the previous season was 0, reflecting known obligate skipped breeding (reproductive omission) that is characteristic of hawksbill populations in response to high energy demands of vitellogenesis and breeding migration. These are the first estimates of annual survival and state-dependent breeding probabilities for any Indo-Pacific hawksbill stock that provide a basis for developing a better understanding of regional population dynamics for this critically endangered species.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online: 15 November 2011

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Biological Sciences Publications
Ecology Centre Publications
 
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