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Evaluating monitoring methods to guide adaptive management of a threatened amphibian (Litoria aurea).

Bower DS, Pickett EJ, Stockwell MP, Pollard CJ, Garnham JI, Sanders MR, Clulow J, Mahony MJ - Ecol Evol (2014)

Bottom Line: Population monitoring programs provide the tools necessary to identify and detect decreases in abundance that will threaten the persistence of key populations and should occur in an adaptive management framework which designs monitoring to maximize detection and minimize effort.Tadpole trapping and auditory surveys did not predict overall abundance and were therefore not useful in detecting declines.Once this has been achieved, capture encounter surveys provide a cost-effective method of effectively monitoring trends in occupancy, changes in relative abundance, and detecting recruitment in populations.

View Article: PubMed Central - PubMed

Affiliation: School of Environmental and Life Sciences, The University of Newcastle University Dr. Callaghan, Newcastle, New South Wales, 2308, Australia.

ABSTRACT
Prompt detection of declines in abundance or distribution of populations is critical when managing threatened species that have high population turnover. Population monitoring programs provide the tools necessary to identify and detect decreases in abundance that will threaten the persistence of key populations and should occur in an adaptive management framework which designs monitoring to maximize detection and minimize effort. We monitored a population of Litoria aurea at Sydney Olympic Park over 5 years using mark-recapture, capture encounter, noncapture encounter, auditory, tadpole trapping, and dip-net surveys. The methods differed in the cost, time, and ability to detect changes in the population. Only capture encounter surveys were able to simultaneously detect a decline in the occupancy, relative abundance, and recruitment of frogs during the surveys. The relative abundance of L. aurea during encounter surveys correlated with the population size obtained from mark-recapture surveys, and the methods were therefore useful for detecting a change in the population. Tadpole trapping and auditory surveys did not predict overall abundance and were therefore not useful in detecting declines. Monitoring regimes should determine optimal survey times to identify periods where populations have the highest detectability. Once this has been achieved, capture encounter surveys provide a cost-effective method of effectively monitoring trends in occupancy, changes in relative abundance, and detecting recruitment in populations.

No MeSH data available.


Size class structure of the Brickpit and Kronos Hill/Wentworth Common during capture encounter surveys over 5 years of Litoria aurea monitoring at Sydney Olympic Park. The figure depicts the low recruitment in Kronos Hill/Wentworth Common during 2010/2011 and 2011/2012 and the increase in juvenile abundance following a management intervention in the 2012/2013 season. (J, juvenile; M, male; F, female).
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fig02: Size class structure of the Brickpit and Kronos Hill/Wentworth Common during capture encounter surveys over 5 years of Litoria aurea monitoring at Sydney Olympic Park. The figure depicts the low recruitment in Kronos Hill/Wentworth Common during 2010/2011 and 2011/2012 and the increase in juvenile abundance following a management intervention in the 2012/2013 season. (J, juvenile; M, male; F, female).

Mentions: The abundance of L. aurea varied in the population between 2008 and 2013 (Fig. 1). Population size of L. aurea in the Brickpit was variable but did not decrease over time, whereas the population trend in Kronos Hill/Wentworth Common was negative during monitoring. The decline in Kronos Hill/Wentworth Common population size corresponded with a reduction in occupancy from 5 to 15 ponds during the 2008–2010 period, to two to five ponds during surveys in 2011. This decline in occupancy was reflected in the few juveniles seen in the size class structure histogram (Fig. 2) and prompted a captive breed and release management intervention in September 2012 and consequently occupancy increased later in 2013.


Evaluating monitoring methods to guide adaptive management of a threatened amphibian (Litoria aurea).

Bower DS, Pickett EJ, Stockwell MP, Pollard CJ, Garnham JI, Sanders MR, Clulow J, Mahony MJ - Ecol Evol (2014)

Size class structure of the Brickpit and Kronos Hill/Wentworth Common during capture encounter surveys over 5 years of Litoria aurea monitoring at Sydney Olympic Park. The figure depicts the low recruitment in Kronos Hill/Wentworth Common during 2010/2011 and 2011/2012 and the increase in juvenile abundance following a management intervention in the 2012/2013 season. (J, juvenile; M, male; F, female).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4020695&req=5

fig02: Size class structure of the Brickpit and Kronos Hill/Wentworth Common during capture encounter surveys over 5 years of Litoria aurea monitoring at Sydney Olympic Park. The figure depicts the low recruitment in Kronos Hill/Wentworth Common during 2010/2011 and 2011/2012 and the increase in juvenile abundance following a management intervention in the 2012/2013 season. (J, juvenile; M, male; F, female).
Mentions: The abundance of L. aurea varied in the population between 2008 and 2013 (Fig. 1). Population size of L. aurea in the Brickpit was variable but did not decrease over time, whereas the population trend in Kronos Hill/Wentworth Common was negative during monitoring. The decline in Kronos Hill/Wentworth Common population size corresponded with a reduction in occupancy from 5 to 15 ponds during the 2008–2010 period, to two to five ponds during surveys in 2011. This decline in occupancy was reflected in the few juveniles seen in the size class structure histogram (Fig. 2) and prompted a captive breed and release management intervention in September 2012 and consequently occupancy increased later in 2013.

Bottom Line: Population monitoring programs provide the tools necessary to identify and detect decreases in abundance that will threaten the persistence of key populations and should occur in an adaptive management framework which designs monitoring to maximize detection and minimize effort.Tadpole trapping and auditory surveys did not predict overall abundance and were therefore not useful in detecting declines.Once this has been achieved, capture encounter surveys provide a cost-effective method of effectively monitoring trends in occupancy, changes in relative abundance, and detecting recruitment in populations.

View Article: PubMed Central - PubMed

Affiliation: School of Environmental and Life Sciences, The University of Newcastle University Dr. Callaghan, Newcastle, New South Wales, 2308, Australia.

ABSTRACT
Prompt detection of declines in abundance or distribution of populations is critical when managing threatened species that have high population turnover. Population monitoring programs provide the tools necessary to identify and detect decreases in abundance that will threaten the persistence of key populations and should occur in an adaptive management framework which designs monitoring to maximize detection and minimize effort. We monitored a population of Litoria aurea at Sydney Olympic Park over 5 years using mark-recapture, capture encounter, noncapture encounter, auditory, tadpole trapping, and dip-net surveys. The methods differed in the cost, time, and ability to detect changes in the population. Only capture encounter surveys were able to simultaneously detect a decline in the occupancy, relative abundance, and recruitment of frogs during the surveys. The relative abundance of L. aurea during encounter surveys correlated with the population size obtained from mark-recapture surveys, and the methods were therefore useful for detecting a change in the population. Tadpole trapping and auditory surveys did not predict overall abundance and were therefore not useful in detecting declines. Monitoring regimes should determine optimal survey times to identify periods where populations have the highest detectability. Once this has been achieved, capture encounter surveys provide a cost-effective method of effectively monitoring trends in occupancy, changes in relative abundance, and detecting recruitment in populations.

No MeSH data available.