KOALA SURVEYS IN THE SOUTHERN TABLELANDS Report Update March 2012 from Chris Allen Introduction This interim report provides a summary, maps and some analyses of the results of the Southern Tablelands koala survey, derived from field surveys undertaken between November 2010 and December 2011. An important feature of the survey program has been the close working relationship with volunteers and the NSW Rural Fire Service (NSWRFS). Both the volunteer’s and agency’s contribution is gratefully acknowledged. Background information, methods, and some results are provided in a previous report1 and the information herein is a continuation the reporting that is in that document. We now know that the core area used by this low-density population extends over approximately 60,000ha, from Calabash in the north to the Kybeyan Nature Reserve in the south. The population may extend further than this, but surveys in adjacent areas are needed to confirm whether or not resident koalas are occupying these areas. Consisting of at least several hundred koalas, this is a significant population nationally. Observations of the systematic and widespread bark-chewing activity reported earlier has have continued in this most recent phase of the fieldwork. This activity appears to be a unique feature of the feeding ecology of the whole population, though is being undertaken more extensively and intensively in some localities than in others. Other indications of the uniqueness of this population are the rugged and generally infertile country and high altitudes in which these koalas occur, and the fact that two unique genotypes have been identified from genetic analysis of samples gathered during the survey. Modelling Koala Activity The high number of grid-sites assessed in the area to the west of Numeralla enable us to delineate koala activity contours for this part of the study area (see Figure 5) with a reasonable level of confidence. We have also modelled koala activity contours in the Calabash, Jerangle and Mt Dowling and Good Good areas. The modelling is based on the results of the tree species preferences analyses (Table 3 and Charts 4 & 5 of this report) of these koalas, and as well as aspect (activity levels are higher 0n northerly aspects) and disturbance history. The modelling has been undertaken to assist NSWRFS planning for proposed autumn fuel reduction burns. The modelling outcome for the Good Good and Mt Dowling areas is shown in Figure 6. I stress that this a tentative and precautionary model, base on extremely limited data, undertaken to assist the NSWRSF in their autumn 2012 fuel reduction program. In areas for

1

EPA (2011). Phase 1 Volunteer Report of Koala Surveys in Southern Tablelands.

which activity models have been provided the agency will plan their fuel reduction burns so that fire is not applied within cells bounded by 10% activity contours. Although I am confident that the risk to koalas being injured in controlled burns will be significantly reduced with this approach, the more fieldwork we can undertake in these areas the greater will be our capacity to model koala distribution more accurately and manage the threat of fire to this population. Volunteers and agency staff are welcome to the fieldwork. If you do wish to participate, please contact Chris Allen at 0417231477 or [email protected]

Summary of data analysis The tables and charts in this report are derived from the data collected in the surveys. We stress that the results presented here are provisional and further data collection and analyses is needed to provide firm conclusions. In summary the results suggest the following: 1. Koala activity is higher in the southern parts of the study area compared with those in the north where the population may be in serious trouble. 2. E. manifera and E. rossii are important tree species for these koalas. 3. These species occur less frequently in the forest eco-systems in the northern section of the study area and is probably a factor in these lower activity levels. 4. Koala pellets are more likely to be found under larger (and older) trees of these species and are probably an important part of the habitat sustaining this population. 5. E. viminalis is also important, but whereas the proportion of trees being used is only slightly higher than the two species above it occurs much less frequently across the study area. 6. There appears to be no size-class preferences for E. viminalis, indeed, even a trend to preference of the smaller size class. However the dataset for this species is too small to be confident in these results. 7. There appears to be no significant difference in the distribution of E. viminalis between the northern and southern sections of the study area. 8. The very limited dataset suggests that E. brigesiana is not important for koalas. However, this may not accurately reflect the importance of this species. In the northern part of the study area E. brigesiana occurs more frequently and pellets were found at several locations on ridgetop areas under this species. 9. The koala’s use of Callitris columellaris appears to be important (probably as a shady roost tree) in areas where it occurs, though its distribution in the study area is very limited. 10. Activity levels in the area of west Numeralla that was burnt in 1993 tend to be lower than, that which was unburnt, suggesting that this fire has degraded habitat values. 11. Northerly aspects have a significantly higher level of koala activity than other aspects. Mapping results Figure 1 (overleaf) maps the results of the survey across the study area. These results are overlaid on a forest eco-systems layer that was developed for the souther Region’s Comprehensive Regional Assessment Process. Figures 2-4 show these results at a finer scale in the Northern, Central and Southern sections of the study area. Activity levels of the RGBSAT sites, pellet locations recorded in transect surveys, and sightings are also shown on these maps.

Figure 1

Figure 2

Figure 3

Figure 4

Data Analysis The information collected at the 86 RGBSAT sites assessed to date has been entered into a database. The following information is derived from queries of these data.

Trends in activity levels across the study area Study area was sub-divided into three localities for analyses purposes. a) Southern: Numeralla and Macanally Mountain. The Numeralla data is a subset of data from this locality, but is also included separately in the tables and figures below. b) Central: Black Ridge, Good Good and Mt Dowling c) Northern: Jerangle, Calabash and Tinderry In assessing differences in activity levels in the different localities, only data from 1km interval RGBSAT sites were included as the initial selection of these survey sites was relatively unbiased. Most 500m interval sites were selected near to locations where koala activity had been identified at nearby 1km interval sites so it is likely that including these will give a biased result as to the trends in activity levels. Table 1 provides a summary of the 1km sites assessed by locality, the number of those that were active, the proportion of active sites and average activity level.

Summary of data from 1km RGBSAT Sites Numeralla

All

South

Central

North

RGBSAT sites

59

12

20

18

22

Active sites

28

10

14

8

6

31 6%

2 10%

6 9%

10 7%

16 1%

12% 47%

13% 83%

13% 81%

16% 44%

4% 27%

Inactive sites Average activity level of all sites Average activity level of active sites Proportion of active sites

Charts 1 – 3, below, provide visual summaries of these data Chart 1: Numbers of sites assessed, and those which were active and inactive

Active/inactive sites 70 60 50 40

RGBSAT sites

30

Active sites

20

Inactive sites

10 0 All

Numeralla

South

Central

North

Chart 2: Average activity levels, by area

Average activity levels 18% 16% 14% 12% 10% 8% 6% 4% 2% 0%

Average activity level of all sites

th No r

ra l Ce nt

th So u

er all a Nu m

Al

l

Average activity level of all active sites

Chart 3: Proportions of active sites

Proportion of active sites 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

th No r

ra l Ce nt

th So u

er all a Nu m

Al

l

Proportion of active sites

Tree species preferences Table 2 provides the species code used in the fieldwork and data analyses, botanical namesand common names for the more commonly occurring species in the dataset. Table 3 provides information on tree species preferences of these koalas. In this case the results from all active sites assessed to Dec 2011 are included. The evidence of one or more pellets at a particular site (ie the site is active) indicates that the koala visited the site and made a decision as to which tree/s to occupy. The summed data of presence/absence of pellets under each species at these sites provides a measure of the koalas’ tree species preferences. Inactive sites (ie those sites where no pellets were located) are not included as no decision-making by a koala can be reflected in the data. Table 2: Code, botanical name and common name for the more commonly occurring species in the dataset Code

Botanical Name

Common name

Ccol

Callitris columellaris

White cypress pine

Ebri

Eucalyptus bridgesiana

Applebox

Ediv

Eucalyptus dives

Broad-leafed peppermint

Emac

Eucalyptus macrorynchia

Red stringybark

Eman

Eucalyptus manifera

Brittle gum

Eros

Eucalyptus rossii

Scribbly gum

Erub

Eucalyptus rubida

Candlebark

Evim

Eucalyptus viminalis

Ribbon gum

Table 3: Tree species preferences from all 1km sites ALL ACTIVE SITES: TREE SPECIES SAMPLED/WITH PELLETS C.col E.bri E. div E. mac E. man E. ros Number sampled 32 31 223 192 290 513 Number with pellets 12 2 14 21 49 72 Number without pellets 20 29 209 171 241 441 Proportion with pellets 0.38 0.06 0.06 0.11 0.17 0.14

E. rub 71 10 61 0.14

E. vim 61 13 48 0.21

Charts 4 & 5 provide a visual summary of the tree species preference data Chart 4: Number of trees of each species sampled and the number of those with pellets

Number sampled/with pellets Number sampled/with pellets

600 600 500 500 400 400

Number sampled

300

Number Number with sampled pellets

300 200

Number with pellets

200 100 100 0 E. man E. div E. mac E. rub E. vim 0 E. ros E. ros E. man E. div E. mac E. rub E. vim

C.col C.col

E.bri E.bri

Chart 5: Proportion of trees of each species sampled with pellets

Size-class preferences The table and chart below provide a summary of trends in the data regarding the koalas’ preference for larger or smaller sizes of each tree species Table 4: Species size class preferences TREE SPECIES WITH PELLETS AT ACTIVE SITES AND RELATIONSHIP WITH DBH Eman 300

Eros Eros Erub Erub Ediv Ediv Emac Emac Ebri Ebri Evim Evim 300 300 300 300 300 300

125

165

224

288

32

39

110

12

37

27

45

2

8

4

113

101

91

13

18

12

49

10

13

8

1

1

4

9

Chart 6: Size-class preferences of selected species

300 250 200 150 100 With pellets

50

Sampled

Evim>30

With pellets Evim15-29

Emac>30

Emac15-29

Ediv >30

Ediv 15-29

Eros >30

Eros15-29

Eman>30

Eman15-29

0

Aspect preferences The data from west Numeralla was also analysed for aspect preferences with the following results in the chart below. Charts 9: Comparison of results by aspect

Aspect/average activity level 25% 20% 15% Aspect/average activity level

10% 5% 0% N

E

S

W

Modelling Activity Contours Figure 5 shows the koala activity contours for the more intensively surveyed area to the west of Numeralla (NB in this figure the contours shown are indicative). These are derived from the activity level values of the assessed sites. In this figure the area within the 20% contour (purple) delineates the activity cell area that has the highest level of koala activity. The area between the 10% (red) and 20% has less, though still significant level of koala activity and that between the 3% (yellow) and 10%, is still used by koalas, but less intensively. These cell boundaries can be refined using the Geographic Information System mapping tool described as regularised splining. Activity cells may encapsulate only one survey site but are generally clusters of sites where Koala evidence was located. Activity cells are approximately analogous to home-ranges. However, the area within an activity cell may be being used by more than one animal. Figure 5

Figure 6, below shows the outcome of the modelled koala activity contours in the Mt Dowling and Good Good areas.