Assessment of the status of threatened herpetofauna following fire in sub alpine habitat at Lake Mountain and Mount Bullfight, near Marysville, north-east Victoria

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1.5 Project objectives

The aim of this study was to determine if the Alpine Tree Frog, Alpine Bog Skink and the Mountain Skink occupy the Lake Mountain Plateau and Mount Bullfight NCR in the second year since fire, and to compare these results to the 2009/2010 surveys. Specifically, this project aimed to:

• reassess and determine post-fire persistence of Alpine Tree Frogs and the Alpine Bog Skink at Lake Mountain and Mount Bullfight NCR;

• attempt to detect any threatened herpetofaunal species, other than those recorded in 2009/2010 are present at Lake Mountain and Mount Bullfight NCR;

• provide management advice to Parks Victoria about practices required to maintain and enhance habitat for threatened species detected during the project.

Figure 1. Location of Lake Mountain and Mount Bullfight Nature Conservation Reserve, and the extent of the fire that affected the area, starting on 7th February 2009.

Figure 2. Historic records of the Alpine Tree Frog Litoria verreauxii alpina (sources: Victorian Fauna Database, Atlas of New South Wales Wildlife database, Museum Victoria, Australian Museum).

Figure 3. Distribution of the Alpine Bog Skink Pseudemoia cryodroma (source: Victorian Fauna Database). Note – this map represents records up to 2007. More recent records do not appear on this database.

2 Methods

2.1 Study areas

Lake Mountain is located at the western edge of the alpine/subalpine zone of mainland Australia (Parks Victoria 2002). The plateau rises to 1480 m in altitude, although much of it is at altitudes of 1250 to 1450 m (ARC and DCE 1990), and may be considered subalpine. Wetland vegetation communities at Lake Mountain cover around 2.5% of the area above 1300 m (Hargreaves 1977). Figures 4 and 5 display the location of Lake Mountain and the sites surveyed during this project.

Most of Mount Bullfight NCR is higher than 1300 m and is dominated by subalpine vegetation. The wetland areas are more restricted and cover only about 1% of the area above 1300 m (Tolsma and Shannon 2009). During 2009/2010 only the lower bog system at Mount Bullfight NCR was surveyed. In the 2010/2011 season, surveys were expanded to include the bog system located upslope. The upper bog system consisted of five separate bog areas up to 320 m apart (Figure 4 and 6).

2.2 Frog surveys and testing for the Amphibian Chytrid Fungus

Frog surveys were conducted at Lake Mountain on the
nights of 30 November and 22 December 2010. Day surveys were also conducted opportunistically on 1 December 2010 and 16 February 2011. The lower bog at Mt Bullfight NCR was surveyed on 18 and 24 November 2010. The upper
bog could not be surveyed at night due the distance from the road and the dangerous terrain leading to the peak.
It was surveyed during the day and late afternoon on
19 November 2010.

During night surveys, time and air temperature were recorded at the start of each survey. A period of 10 minutes was spent listening for frogs, identifying and estimating the number of calling individuals. A visual search (aided by torchlight) was undertaken to capture frogs.

Captured frogs were swabbed to test for Amphibian Chytrid Fungus. Swabbing of frogs involved rubbing a sterile swab (Medical Wire and Equipment, MW-100) along the ventral and dorsal surfaces, in the groin area, and underneath
the hand as the frog gripped the swab. Each swab was labelled with the site number, species and date. After swabbing, frogs were released at their points of capture. New disposable gloves were used to handle each frog in order to prevent transmission of the fungus between individuals. To prevent the spread of pathogens researcher’s hands and footwear were sprayed with a solution of methylated spirits and water between sites. Swab samples were sent to EcoGene in New Zealand to test for the Amphibian Chytrid Fungus. EcoGene analysed the samples by Taqman real-time PCR assay, using the methods described by Hyatt et al. (2007).

We inferred the most likely values and 95% confidence intervals for Amphibian Chytrid Fungus prevalence (proportion of individuals infected) by applying the binomial probability distribution to the diagnostic testing data from Mount Bullfight NCR and Lake Mountain. A binomial test was used to test the null hypothesis that the prevalence of fungal infection was equal in the two populations.

2.3 Lizard surveys

Transects of artificial cover-objects, consisting of 10 secondhand roof tiles, were deployed to survey for
reptiles at Lake Mountain and at both the upper and
lower bogs at Mount Bullfight NCR, whereas only visual searches were used in the first year of this study. Tiles have proven to be an effective method to survey for alpine reptiles (e.g. Clemann 2011). Each tile was lifted during surveys and reptiles sheltering underneath were captured by hand. For more detail on the survey method see Clemann (2011). All tiles deployed to Mount Bullfight NCR were thoroughly cleaned, disinfected and dried prior to deployment to minimise any potential spread of the Amphibian Chytrid Fungus.

Seven transects were randomly spread between the major bogs throughout the Lake Mountain plateau on 30 November and 22 December 2010 (Figure 5). At Mount Bullfight NCR, four transects were placed throughout the lower bog on 18 and 24 November 2010. Five transects were placed at the five bogs that form the large upper bog system on 19 November 2010 (Figure 6).

The seven tile transects at Lake Mountain were surveyed three times - on 16 February and 3 and 29 March 2011. In addition to this, Transect 1 and 2 were surveyed on 1 December 2010, and Transect 2 again on 22 December 2010.

At Mount Bullfight NCR, the four transects in the lower bog were surveyed four times - on 25 November 2010, and 1 and 16 March, and 7 April 2011. Additionally, Transects B1 and B2 were surveyed on 24 November 2010. The five transects on the upper bog at Mount Bullfight NCR were surveyed three times on 2 and 17 March and 8 April 2011.

Each captured lizard was photographed for later confirmation of identification. Where time permitted, general surveying for herpetofauna was also conducted at each site. This involved rock-rolling and searches for basking lizards on vegetation, rocks and logs. Environmental variables including air temperature, rain, cloud cover, sunlight and wind were recorded at each transect at the time of survey.

3 Results

Ten months after the Black Saturday fires little regeneration of ground-level vegetation was evident in many of the areas surveyed (Figure 7). During the second season of this study, 21 months after the fires, there was marked increase in vegetation cover. Ground-level vegetation had recovered in most of the bog areas, sphagnum was growing on the bog margins and small heaths were establishing (Figure 8).

Additional sites were surveyed in 2010/2011 at Mount Bullfight NCR, with the inclusion of five upper bogs on the summit of Mount Bullfight. In this area, not all sites were extensively burnt compared to Lake Mountain. Site UB3 suffered minor burning and Sites UB1 and UB4 were burnt in patches. Sites UB2 and UB5 were completely burnt (Figure 9).

Figure 7. Bog at Lake Mountain 10 months after the Black Saturday fires.

Figure 8. Bog on Echo Flat, Lake Mountain showing vegetation regrowth 21 months after the Black Saturday fires.

Figure 9. Site UB3 (top), UB4 (middle) and UB5 (bottom) on the summit of Mount Bullfight showing differing degrees of burn severity during the 2009 fires.

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