Golden Sun Moth Population and Habitat Monitoring| SMEC
Prepared for: Parks and Conservation Service / Environmental Offsets
Date: April 2016
SMEC | Golden Sun Moth Population and Habitat Monitoring Program| 26 | Page
Golden Sun Moth Population and Habitat Monitoring| SMEC
Document ControlTitle / Golden Sun Moth Population and Habitat Monitoring Program
Prepared for / Parks and Conservation Service/Environmental Offsets
Project Ref / 3002494
Name / Position / Signed/Approved / Date
Originator / Natasha Crook / Ecologist
Review / David Moore / Senior Scientist
Approval / Dr Robert Jessop / Principal Scientist / Dr Robert Jessop / 24/03/2016
Details of Revisions
Rev / Date / Description / Approved
1 / 29042016 / Final Report / Dr Robert Jessop
CONTACT DETAILS
SMEC Australia Pty Ltd | www.smec.com
Level 5, 20 Berry Street
North Sydney NSW 2060
Tel: 02 9925 5555
Fax: 02 9925 5566
Representative: Robert Jessop
P: 02 6234 1924
E:
TABLE OF CONTENTS
Executive summary 4
1. INTRODUCTION 5
1.1 Project Overview 5
1.2 Golden Sun Moth 5
1.2.1 Description 5
1.2.2 Life History and Breeding 5
1.2.3 Habitat 6
1.2.4 Distribution 6
1.2.5 Conservation Status and Threats 7
1.3 Study Area 7
2. Methods 8
2.1 Golden Sun Moth Monitoring 8
2.1.1 Field Surveys 8
2.1.2 Transect Survey 8
2.2 Habitat Assessment 8
2.2.1 Step Point Transects 8
2.2.2 Photograph Monitoring Points 9
3. Results 10
3.1 GSM Survey Results 10
3.1.1 Throsby North 11
3.1.2 Kinlyside 12
3.1.3 Bonner 4 East 12
3.2 Vegetation monitoring 13
3.2.1 Throsby North 13
3.2.2 Kinlyside 13
4. Conclusion 17
References 18
APPENDICES 27
Executive summary
Parks and Conservation Service and Environmental Offsets (Territory and Municipal Services) engaged SMEC Australia to undertake baseline Golden Sun Moth (GSM) population surveys and habitat monitoring across Throsby North, Kinlyside and Bonner 4 East environmental offset areas during spring and summer 2015. The surveys are intended to meet monitoring requirements established for Throsby North and Kinlyside by the Offset Strategy in the Gungahlin Strategic Assessment Biodiversity Plan (Umwelt, 2013) and for Bonner 4 East by Commonwealth approval conditions for the development of Ngunnawal Residential Estate 2C (EPBC 2010/5648).
GSM and habitat monitoring was undertaken in accordance with the Survey Guidelines for Golden Sun Moth (ACT Government, 2010) and the Draft ACT Golden Sun Moth Monitoring Plan (ACT Government, 2013) to determine if GSM persist in these sites, and to ensure that management actions and the habitat remain suitable to support viable GSM populations into the future.
Results of GSM surveys and habitat monitoring were recorded and are presented in a form suitable for incorporation into future analyses. The surveys had the following general outcomes:
· GSM were recorded, generally in low numbers at each of the three sites during the first surveys in November
· Numbers dropped significantly by mid-December, with no moths observed during the second surveys at Kinlyside and Bonner 4 East; this is likely to be due to very low night time minimum temperatures inhibiting GSM emergence
· GSM numbers and distribution in Throsby North are consistent with the previous surveys, with the majority of moths observed in the southern part of the offset area
· Habitat quality along monitoring transects in Throsby North was variable, with a high proportion of exotic annual grasses
· GSM numbers and distribution in Kinlyside were broadly consistent with previous surveys, with the majority of observations observed in grassy areas in the central and south west of the offset area
· Habitat quality along monitoring transects was generally good, with high proportions of native perennial grasses present
· GSM were observed across the majority of Bonner 4 East, with the highest abundance in the centre of the offset area
1. INTRODUCTION
1.1 Project Overview
Parks and Conservation Service and Environmental Offsets (Territory and Municipal Services) engaged SMEC Australia to undertake Golden Sun Moth (GSM) population surveys and habitat monitoring across Throsby North, Kinlyside and Bonner 4 East environmental offset areas during spring and summer 2015. Figure 1 shows the study site locations.
The Throsby North and Kinlyside offsets areas were established under the Gungahlin Strategic Assessment (i.e. approved by the Australian Government Environmental Minister in June 2013) for future urban development in Gungahlin (Australian Government, 2013; Umwelt, 2013). The offsets were proposed as part of the Offset Strategy in the Gungahlin Strategic Assessment Biodiversity Plan (Umwelt, 2013) to compensate for the significant impacts to Matters of National Environmental Significance (i.e. Commonwealth listed ecological communities and threatened species) due to urban development. This includes the adverse impact of development on 180ha of GSM habitat (Umwelt, 2013).
Bonner 4 East was included in the monitoring project to meet the Commonwealth approval conditions for the development of Ngunnawal Residential Estate 2C (EPBC 2010/5648).
Annual monitoring of Throsby North and Kinlyside is scheduled for the first three years after offset establishment and then once every three years. Monitoring at Bonner 4 East is currently scheduled to occur once every five years.
The following report presents the 2015 monitoring results, providing baseline information on GSM population and habitat condition for ongoing monitoring requirements.
1.2 Golden Sun Moth
1.2.1 Description
Golden Sun Moth (GSM) (Synemon plana) is a medium size, diurnal moth. The upper-side of the female’s forewing is dark grey with paler grey patterning, while the hindwing is bright orange with black spots along the edges. The under-side of both wings is white with small black spots along the margins. Adult males have a wingspan of 34mm and have dark brown upper forewings with patterns of pale grey scales. Male hindwings are bronze or brown with dark brown blotches and the underside is pale grey with dark brown spots (Australian Government, 2009).
1.2.2 Life History and Breeding
GSM have two distinct life stages. Larvae spend two to three years underground consuming the roots of native Wallaby grass (Rytidoperma spp.) and exotic Chilean Needle Grass (Nassella neesiana) (Ritcher et al., 2013). Age cohorts are distinguished by size. Small larvae (6 – 13mm long) are from eggs 12 months earlier, medium size (>13-20 mm long) are from the second year and large larvae (>20mm long) are approaching pupation (Ritcher et al., 2013). Pupation occurs in spring and adults emerge from October to January to live for 1- 4 days (Ritcher et al., 2013).
Adult moths do not have functional mouthparts and therefore are unable to feed, spending much of their time searching for mates and breeding. During the GSM flight season, adult moths emerge continuously in cohorts and males are seen actively flying low (to 1 metre) and fast, usually in a zig-zag pattern over the grassland in search of females (Australian Government, 2009). The females, which only fly irregularly, position themselves on the ground in a conspicuous location (i.e. usually inter-tussock spaces), flashing their brightly coloured hind wings to attract males. Females walk between tussocks and lay 100-150 eggs between grass tillers or between tillers and the soil (Australian Government, 2009).
Adults are most active during the hottest part of the day (i.e. between 10am and 2pm) on warm to hot, windless and cloudless days (Ritcher et al., 2009); however, previous surveys (e.g. Biosis Research, 2011) recorded active male moths in more variable weather conditions. Such conditions include: cooler days (i.e. less than 20ºC), days with partial or full cloud cover, on days within 24 hours after rainfall, during periods of moderate to strong wind conditions and also at times earlier and later in the day than previously expected. Activity during these conditions typically involved smaller moth numbers than those observed during ‘optimal’ conditions.
Male GSM cannot travel more than 100m away from suitable habitat patches and therefore populations separated by distances greater than 200m can be considered effectively isolated. Sites from which the species has gone extinct are unlikely to be naturally recolonised (Australian Government, 2009).
1.2.3 Habitat
GSM occurs in Natural Temperate Grasslands and open grassy woodlands. Previous GSM habitat definitions that required the area to be 40% Rytidosperma cover (O'Dwyer and Attiwell, 1999) are no longer considered accurate. GSM have been identified to reside in degraded grasslands dominated by exotic Chilean needle grass, a Noxious Weed of National Significance (Brady and Dunford, 2006). It is believed that tall, dense grasslands are not suitable for moth activity as it can inhibit detection of female moths by flying male moths.
GSM occurs in two threatened ecological communities listed under the Commonwealth Environmental Protection Biodiversity and Conservation Act 1999 (EPBC Act); the Natural Temperate Grassland of the Victorian Volcanic Plain (Australian Government, 1999) and the Natural Temperate Grassland of the Southern Tablelands of New South Wales (NSW) and the Australian Capital Territory(ACT) (Australian Government, 2009). In the ACT, GSM have also been detected within secondary grassland, predominantly those derived from Yellow Box – Blakely’s Red Gum Grassy Woodland.
1.2.4 Distribution
Historically, GSM was distributed in native grasslands and open grassy woodlands across NSW, the ACT, Victoria and South Australia (TSSC, 2013). Since European settlement, GSM is now only known in 125 sites across its range (TSSC, 2013). Forty-eight sites occur in NSW, 46 in Victoria, 39 in the ACT. The species is now extinct in South Australia (TSSC, 2013).
1.2.5 Conservation Status and Threats
GSM are listed as Endangered under the ACT Nature Conservation Act 2014 (NC Act), endangered under the NSW Threatened Species Conservation Act 1995 (TSC Act) and threatened under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act). The species is listed as Critically Endangered under the EPBC Act.
The main threat to GSM is the loss of Natural Temperate Grasslands, which have been cleared for urban and agriculture development (DEWHA, 2009). In addition, habitat degradation through overgrazing, which changes the soil structure, reduces native grass species and promotes weed invasion, has further threatened GSM (DEWHA, 2009). GSM populations have become highly fragmented and isolated.
1.3 Study Area
The Throsby North and Kinlyside offset areas were identified as supporting Commonwealth listed threatened species and ecological communities through the Gungahlin Strategic Assessment process (Umwelt, 2013).
Throsby North is located between Mulligan’s Flat and Goorooyarroo Nature Reserve on north of the proposed suburb of Throsby, to the north-east of Horse Park Drive. The area supports GSM and has large areas of Box-Gum Woodland (Umwelt, 2013). Eco Logical (2011) identified the area as supporting ‘moderate to high’ quality GSM habitat. Over time, Throsby North will be added to the Mulligan’s Flat – Goorooyarroo Nature Reserve complex. Throsby North is managed in accordance with the management plans for both Mulligan’s Flat and Goorooyaroo Nature Reserves (ACT Government, 2014).
The Kinlyside offset area covers 201ha north-east of Hall, and is adjacent to the eastern boundary of One Tree Hill. Kinlyside is dominated by Box-Gum Woodland with patches of native grasslands and derived grasslands (Eco Logical, 2011). The grassland areas include moderate to high quality GSM habitat.
The Throsby North and Kinlyside offset areas combined support approximately 148ha of GSM habitat. The primary land use within both offset areas is light grazing by sheep and cattle.
Bonner 4 East is 21ha of land on the south-western boundary of Mulligan’s Flat Nature Reserve. Bonner 4 East was established as an offset for adverse impacts on GSM due to the development of Ngunnawal Estate 2C. Territory and Municipals Service (TAMS) and the Land Development Agency (LDA) selected the site, which was identified to have high ecological values including the presence of GSM (ACT Government, 2011).
Bonner 4 East has a history of woodland clearing and long-term stock grazing (ACT Government, 2011). The area comprises secondary grassland and wet Themeda secondary grassland (ACT Government, 2011), which supports GSM. Weeds are dense in the north-eastern part of the area (ACT Government, 2011). Over time, the area will be incorporated into Mulligans Flat Nature Reserve and currently has an offset management plan which involves biomass management and weed control (ACT Government, 2014).
2. Methods
2.1 Golden Sun Moth Monitoring
2.1.1 Field Surveys
Survey methods were in accordance with the guidelines set by Conservation Planning and Research Survey Guidelines for Golden Sun Moth (ACT Government, 2010) and the Draft ACT Golden Sun Moth Monitoring Plan (ACT Government, 2014).
Surveys must be undertaken during the GSM emergence period or ‘flying season’, which is usually from October to December in the ACT.
The guidelines also require GSM surveys to be conducted during certain preferred conditions, specifically:
· On a warm to hot day (i.e. above 20ºC by 10am)
· During the warmest part of the day (i.e. 10am – 2pm)
· When there is a clear or mostly cloudless sky
· In still or nearly still wind conditions
· When there has been at least two days since rain.
Two surveys were undertaken at each offset site at least one week apart.
Incidental observations of female moths and pupae cases were also recorded during the survey and the location recorded with GPS.
While the weather conditions were checked on the survey day, more detailed information was recorded from the Bureau of Meteorology web site (i.e. www.bom.gov.au) to inform the results post survey.
2.1.2 Transect Survey
The ‘walked transect’ method was used to provide quantitative information on GSM abundance and distribution. The entire site is walked in parallel transects 100m apart using a GPS and compass. The total number of GSM within 25m either side of the transect line over 100m sections of each transect is recorded. The surveys are repeated on at least two suitable flying days in a season.
Conservation Research and Planning provided the GPS coordinates of each transect. Transect and transect segment locations are provided in Appendix A.
2.2 Habitat Assessment
2.2.1 Step Point Transects
Vegetation assessments were conducted on 3 (i.e. Throsby North) and 8 (i.e. Kinlyside) December 2015 using the ‘Step Point Transect’ method. The vegetation survey was undertaken during the flying season.
The vegetation transects were undertaken along a 100m measuring tape placed along each transect. Conservation Research and Planning provided the GPS coordinates of each transect. The same transects can be monitoring in subsequent years facilitating vegetation condition comparisons between years.