BHP : GHD 2021a - Jimblebar Targeted Bilby Assessment

BHP Western Australian Iron Ore

East Jimblebar and Caramulla Targeted Greater Bilby Survey

June 2021

Executive summary

BHP Western Australia Iron Ore (BHP WAIO) have commissioned GHD Pty Ltd to undertake a targeted Greater Bilby (Bilby) (Macrotis lagotis) survey of the East Jimblebar and Caramulla area. The survey findings will be used to inform future environmental approvals across the area.

This report is subject to, and must be read in conjunction with, the limitations, assumptions and qualifications contained throughout the Report.

A targeted on-ground survey for Bilby was conducted from the 15 - 20 September 2020 by Principal Zoologist Glen Gaikhorst, and Senior Zoologist Robert Browne-Cooper. Sandplain, Hillcrest/ Hillslope, Mulga Woodland and Major Water course margin habitat occurs within the survey area and wider region is considered as potential habitat for a population of the species.

There are no known Bilby records within the survey area and only one Bilby records within the government database search area (i.e 40 km buffer of survey area). The most recent record was an old Bilby burrow approximately 5.6 km east of the survey area. This burrow was first recorded in 2018 (Biologic 2018), re-assessed in 2019 (GHD 2019) and again for this project with no change (no Bilby activity recorded) to the status of the burrow. All other Bilby records are greater than 24 years old and general in location with no confirmation of occurrence.

The Bilby habitat and targeted survey was undertaken primarily using a 2 ha plot method (Southgate et al. 2018). The 2 ha method is an evidence-based assessment which records digs, burrows, scats and prints where observed. Evidence of other fauna were also recorded to establish confidence in the results, but was not the main focus of this survey.

Forty-seven Bilby plots were searched covering approximately 94 ha. None of these plots recorded any evidence of Bilby activity. Tracks and other signs from a range of small fauna were detected within a number of search plots, indicating that had Bilby tracks or other signs been present, these would have also been detected.

Seven habitat types were recorded within the survey area and included Sandplain, Stony plain, Mulga Woodland, Hillcrest/hillslope, Clay Pan, Major Drainage Line and Minor Drainage Line. Of these habitats, Sandplain is most suitable to support a population of the Bilby and comprises 967 ha of the survey area. This habitat has substrate suitable for burrowing by the Bilby as well as plant groups which the Bilby is typically associated with. The plant species identified included Acacia colei, A. stellaticeps, A. melleodora and Senna notabilis and all harbour grub invertebrate species that the Bilby predate on.

Similar Sandplain habitat lies adjacent north and east of this area and is suitable for Bilby, however, due to existing disturbances in the region and impacts by grazing and feral species, the survey area is unlikely to support a population of Bilby. Mulga Woodland, Minor and Major Drainage Lines may also provide habitat for the species, however due to the grazing pressures in the region these areas are highly disturbed and any Bilby use would be likely irregular and opportunistic.

The lack of recent records and signs of the species within the survey area makes potential occurrence unlikely despite suitable habitat being present. Suitable extensive habitat is present outside of the survey area and consists mainly of sandplain. Bilby maybe present in the sandplain habitat in these areas.

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Table of contents

1.	Introduction	1
	1.1	Background and purpose of this report	1
	1.2	Scope of works	1
	1.3	Survey area	1
	1.4	Limitations and assumptions	1
2.	Ecology of the Bilby	3
	2.1	Taxonomy and conservation status	3
	2.2	Morphology	3
	2.3	Distribution and habitat	3
	2.4	Diet	3
	2.5	Breeding	4
3.	Environment	5
	3.1	Desktop assessment	5
4.	Methodology	9
	4.1	BHP WAIO requirements	9
	4.2	Relevant legislation and background information	9
	4.3	Desktop assessment and literature review	10
	4.4	Field survey	10
5.	Results	13
	5.2	Targeted survey results	14
6.	Summary	24
7.	References	25

Table index

Table 1 Rainfall 6 months prior to the survey month	5
Table 2 Weather during survey period (BoM 2020)	6
Table 3	Land systems within the survey area	7
Table 4	Previous Bilby records within the database search area (40 km)	13
Table 5	Mulgara burrow location and images	21
Table 6	Survey limitations	22

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Appendices

Appendix A - Figures

Appendix B - Relevant legislation, background information and conservation codes

Appendix C - Field data

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1. Introduction

1.1 Background and purpose of this report

BHP Western Australian Iron Ore (BHP WAIO) commissioned GHD Pty Ltd (GHD) to undertake a targeted Greater Bilby (Bilby) (Macrotis lagotis) survey of the East Jimblebar and Caramulla area (hereafter referred to as the survey area). This report details the findings of the September 2020 targeted Bilby survey.

This targeted Bilby assessment will be used to inform future environmental approvals across the area and inform the Matters of National Environmental Significance (MNES) monitoring programs conducted as a commitment under BHP WAIO's Commonwealth Strategic Approval. This survey report documents the findings for the survey area, rather than assess a specific development proposed by BHP WAIO.

1.2 Scope of works

The scope of works was to:

• Conduct a targeted Bilby survey that aligns with the Bilby Survey Guidelines (DBCA 2017a) and employs search plot analysis to assess Bilby occupancy and detectability. This analysis is based on the method developed by Richard Southgate et al. 2018 (Section 4.5)
• Undertake a habitat assessment and identify any potential habitat for Bilby use
• Produce a technical report (this document) detailing the method and findings of the survey
• Submit associated spatial data in accordance with BHP WAIO guidance documents and the Index of Biodiversity Surveys for Assessment (IBSA) requirements.

1.3 Survey area

The survey area is located approximately 45 km from Newman and 5 km directly east of the Jimblebar BHP WAIO mining operation covering an area of approximately 8,839 ha (Figure 1). The survey area encompasses active/ non-active Geoscience tenure, off-tenure and active mine areas.

For this report, the database search area includes the survey area and an additional 40 km radius buffer around the centre point of the survey area (23°21'53"S, 120°14'23"E). The database search area defines the limits of the desktop assessment as described in Section 4.4.

1.4 Limitations and assumptions

This report has been prepared by GHD for BHP WAIO and may only be used and relied on by BHP WAIO for the purpose agreed between GHD and the BHP WAIO as set out section 1.1 of this report.

GHD otherwise disclaims responsibility to any person other than BHP WAIO arising in connection with this report. GHD also excludes implied warranties and conditions, to the extent legally permissible.

The services undertaken by GHD in connection with preparing this report were limited to those specifically detailed in the report and are subject to the scope limitations set out in the report.

GHD has prepared this report on the basis of information provided by BHP WAIO and others who provided information to GHD (including Government authorities), which GHD has not independently verified or checked beyond the agreed scope of work. GHD does not accept liability

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in connection with such unverified information, including errors and omissions in the report which were caused by errors or omissions in that information.

The opinions, conclusions and any recommendations in this report are based on conditions encountered and information reviewed at the date of preparation of the report. GHD has no responsibility or obligation to update this report to account for events or changes occurring subsequent to the date that the report was prepared.

The opinions, conclusions and any recommendations in this report are based on assumptions made by GHD described in this report. GHD disclaims liability arising from any of the assumptions being incorrect.

The opinions, conclusions and any recommendations in this report are based on information obtained from, and testing undertaken at or in connection with, specific sample points. Site conditions at other parts of the site may be different from the site conditions found at the specific sample points.

Site conditions may change after the date of this Report. GHD does not accept responsibility arising from, or in connection with, any change to the site conditions. GHD is also not responsible for updating this report if the site conditions change.

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2. Ecology of the Bilby

2.1 Taxonomy and conservation status

The Bilby is the sole remaining representative of the sub-familyThylacomyinae in the Bandicoot family and one of few medium sized terrestrial mammals remaining on mainland Australia. Many species in this 'critical weight range' have become extinct since European settlement of Australia. The declines have been attributed to causal factors including increased grazing pressure, inappropriate fire regimes, competition with European rabbits (Oryctolagos cuniculus) and predation by introduced carnivores such as foxes (Vulpes vulpes), cats (Felis catus) and wild dogs (Canis familiaris subsp. familiaris) (Pavey 2006).

The Bilby is given "threatened" status under State and Commonwealth legislation. In Western Australia, the Bilby is listed as 'Vulnerable' under Western Australia's Biodiversity Conservation Act 2016 (BC Act). Nationally it is also listed as 'Vulnerable' under the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Internationally, this species is listed as Vulnerable on the IUCN Red List of Threatened Species.

2.2 Morphology

The Bilby shows sexual dimorphism with adult males reaching between 0.8 kg and 2.5 kg as compared to the smaller females at 0.6 kg to 1.1 kg. The Bilby has a distinctive appearance with long slender hind legs, small front limbs, a long tail, rabbit-like ears and a long pointed snout. The animal has silky grey fur with a proximally black and distally white tail.

2.3 Distribution and habitat

Bilby once occurred across most arid and semi-arid areas of mainland Australia. In Western Australia Bilbies are now largely restricted to the Gibson, Little Sandy and Great Sandy Deserts as well as parts of the Pilbara, Dampierland, Central Kimberley and Ord-Victoria Plains Bioregions.

Populations known from the Pilbara Bioregion have been recorded in the Hamersley Range area, along the Fortescue River and north-east of Shay Gap. Within the Pilbara Bioregion the Bilby mainly occupies sandy areas in dune systems, along drainage systems, sandplain or rocky loam plains or undulating hills habitat. Records of the species in the survey area and in the vicinity of the survey area discussed in Section 5.1.1.

Bilbies are solitary, nocturnal animals. They usually shelter in burrows during the day and intermittently at night for refuge. Burrows can be 3 m deep and some are complex systems with multiple entrances and interconnecting burrows. An individual Bilby may regularly utilize over a dozen burrows within its home range. The species is highly mobile and have been recorded using burrows over 2 km apart on consecutive days. Studies on the home range size of Bilbies range from 1 km2 to over 3 km2 (Pavey 2006).

Bilby are a highly mobile species which may be driven by the availability of resources (Strahan 1995), but can also persist in areas of low productivity (Southgate and Carthew 2007, Southgate et al. 2007 and Southgate et al. 2018).

2.4 Diet

Bilbies are omnivorous and many utilise an array of food resources over the landscape depending on seasonal availability and fire history. Food sources include, but are not limited to, grass, sedge seeds, ants, fungi, termites, beetles, insect larva and spiders. Some plant species are utilised to harvest insect larvae by Bilby and in the Pilbara include Acacia bivenosa, A. colei, A. dictyophleba,

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A. melleodora, A. stellaticeps, A. trachycarpa, A. trachycarpa - dwarf variant and Senna notabilis (Southgate et al. 2018). The main insect larval group recorded in these species are from the family Cossidae (Dziminski and Carpenter 2017, Southgate et al. 2018) or Miller Moths. The Bilby is recognized as an ecosystem engineer as it often digs for food and this process creates variation in micro-habitatfunction.

2.5 Breeding

The Bilby can breed throughout the year and like many Australian arid-zone mammals can produce young quickly to take advantage of seasonal conditions and food availability. Bilbies have a polygamous mating strategy where males may mate with multiple females. Bilby gestation is 12 days long and young spend approximately 75 days in their mother's pouch before being left in the maternal burrow and weaned over two weeks (DBCA 2017b). Young generally become independent at three months of age. Female bilbies are sexually mature from five months of age while males reach sexual maturity after eight months of age. Bilbies can breed up to four times per year and one or two young are usually produced per litter (mean 1.94), however they can produce up to three young per litter (DSEWPaC 2013).

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3. Environment

3.1 Desktop assessment

3.1.1 Regional biogeography

The survey area is situated in the Eremaean Botanical Province, within the Pilbara Bioregion and the Fortescue Sub-region (PIL2) as described by the Interim Biogeographic Regionalisation of Australia. The Pilbara Bioregion is characterised by vast coastal plains and inland mountain ranges with cliffs and deep gorges. Vegetation is predominantly mulga low woodlands or snappy gum over bunch and hummock grasses. Tenure comprises Aboriginal land, leasehold (for grazing cattle) and conservation reserves. The bioregion provides the majority of Western Australia exports in petroleum, natural gas and iron ore. Major population centres are Karratha, Port Hedland, Newman and Tom Price.

3.1.2 Climate

The survey area is located within the Pilbara region of WA. The climate of this region is arid to tropical with very hot summers and mild winters. Rainfall in the Pilbara is spatially and temporally variable. Rainfall in the eastern Pilbara (containing the survey area) is most influenced by tropical and monsoonal drivers which are predominantly active in the summer and autumn months (December - May) whilst rainfall in the western Pilbara is also influenced by southern mid-latitude drivers such as frontal systems during autumn and winter (March - August) (Sudmeyer 2016).

During summer and early autumn (December - March), average daily temperatures exceed 30°C across the region, with average daily maxima exceeding 35°C from October to March. During the winter months (June - August), average temperatures are around 20°C across the region.

The closest current weather station to the site is in Newman Airport (Station ID: 007176) located approximately 60 km west of the survey area boundary. Climate data from this station indicate:

• Mean maximum temperature ranges from 22.8 °C in July to 39.1 °C in December
• Mean minimum temperature ranges from 6.4 °C in July to 24.9 °C in January
• Mean annual rainfall is 334.9 mm with an average of 38.7 rain days per year (Bureau of Meteorology (BoM) 2020).

Rainfall for the previous 6 month lead up to the survey is presented Table 1 (based on Newman Airport data). The rainfall total for the previous 6 months is 28.4 mm. This is approximately 8.7 percent of the year's long-term mean annual for the Newman area. The 6 month average of 28.4

1. is below average of the months assessed, with the long-term average for the same period being 117.4 mm. When compared to the previous 2 years, 2018 and 2019 mean rainfall for the same period was 68.2 and 13.9 mm respectively. Both 2018 and 2019 were below the annual rainfall for the year and considered drier than normal.

Table 1 Rainfall 6 months prior to the survey month

Date	Rainfall (mm)
August 2020	2.2
July 2020	0
June 2020	1.0
May 2020	7.4
April 2020	17.4
March 2020	0.4

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Date

Total

Rainfall (mm)

28.4

During the survey the weather was warm to hot. The weather over the survey period is presented in Table 2. There were no rain events in the four weeks prior to or during the survey, which precludes rain having an impact on the ability to detect some Bilby evidence.

Table 2 Weather during survey period (BoM 2020)

Date

14 Sept. 2020

15 Sept. 2020

16 Sept. 2020

17 Sept. 2020

18 Sept. 2020

19 Sept. 2020

20 Sept. 2020

Temperature (°C)		Rainfall (mm)
Minimum	Maximum
19.0	35.8	0
17.3	36.2	0
20.8	37.4	0.
18.0	27.3	0
9.6	29.9	0
14.7	37.3	0
25.4	35	0

3.1.3 Land systems, landforms and soils

Three soil types intersect the survey area and comprise the following (Bureau of Regional Sciences 2009):

• BE6: Extensive flat and gently sloping plains, which sometimes have a surface cover of
  gravels and on which red-brown hardpan frequently outcrops: chief soils are shallow earthy loams (Um5.3), with associated (Gn) soils of units My5O and Mz23 of Sheet 6. As mapped, there are inclusions of units Oc47 and BB9
• Mz25: Plains associated with the Fortescue valley; there is a surface cover of stony gravels
  close to the ranges and hills: chief soils are acid red earths (Gn2.11) with some neutral red earths (Gn2.12); red-brown hardpan is absent. Associated are areas of calcareous earths (Gc) and loams (Um1) on calcrete (kunkar) and some hard red (Dr) soils around creek lines
• Fa13: Ranges of banded jaspilite and chert along with shales, dolomites, and iron ore formations; some areas of ferruginous duricrust as well as occasional narrow winding valley plains and steeply dissected pediments. This unit is largely associated with the Hamersley and Ophthalmia Ranges. The soils are frequently stony and shallow and there are extensive areas without soil cover: chief soils are shallow stony earthy loams (Um5.51) along with some (Uc5. 11) soils on the steeper slopes. Associated are (Dr2.33 and Dr2.32) soils on the limited areas of dissected pediments, while (Um5.52) and (Uf6.71) soils occur on the valley plains.

The Pilbara region has been surveyed by the Department of Agriculture and Food, Western Australia and others for the purposes of land classification, mapping and resource evaluation. One hundred and two land systems have been described for the region, which are distinguished on the basis of topography, geology, soils and vegetation (Van Vreeswyk 2004). The survey area intersects 10 mapped land systems; details of these are presented in Table 3.

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