Searching and trapping for Mulgara in the Pilbara Graham Thompson - - PowerPoint PPT Presentation

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Searching and trapping for Mulgara in the Pilbara

Graham Thompson Scott Thompson

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Dasycercus sp.

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Motivation for this research

The above statement was taken from an EPBC referral in 2012 for a site within 1km of the area that has the highest recorded density of Mulgara in the Pilbara and where the habitat was almost identical!

Failure to identify Mulgara habitat

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Motivation for this research

This area probably supported Mulgara, and was not referred under the EPBC Act

Failure to identify Mulgara habitat

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Motivation for this research

Failure to detect burrows

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Motivation for this research

Mis-identification of burrows

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Mulgara burrows

• How many people doing field work in the Pilbara have actually dug Mulgara from a

burrow or followed a Mulgara to a burrow and know what Mulgara burrows look like?

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Insufficient trapping effort

Motivation for this research

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Mulgara burrows in the Pilbara

• ‘D’ shaped entrance
• Underground tunnels are generally 60-70mm wide, narrowest at about 40mm

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Simple Mulgara burrow

Elevation not to scale

Thompson and Thompson JRSWA 2007, 90:195-202

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Complex Mulgara burrow

Elevation not to scale

Thompson and Thompson JRSWA, 2007, 90: 195-202

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Complex Mulgara burrow

Elevation not to scale

Thompson and Thompson JRSWA, 2007, 90:195-202

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Spinifex Hopping Mouse borrow

Thompson and Thompson JRSWA 2007, 90: 111-113

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Mulgara burrows in the Pilbara

• Varying number of entrances
• Entrances can be in the open or hidden under spinifex and

shrubs

• Burrows have interconnecting tunnels
• Each Mulgara probably has multiple burrows

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Four case studies all are from the Pilbara, where:

– the terrain is generally flat; – hard, sandy surface, often with surface stones; – low shrubs or hard spinifex of varying densities and heights; and – the landscape is often burnt.

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Case study 1

Thompson and Thompson , JRSWA , 2007, 90: 195-202

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Case study 1

Methods

• Searched in June 2006 (22 person hrs –

44ha)

• Trapped (750 trap-nights) and all burrows

were dug out in Jan 2007

Results

• Only 9 burrows found in the 2006 search
• 65 burrows dug out after fire in Jan 2007
• 4 Mulgara trapped, 5 more dug out
• Mulgara trapped on nights 1, 2, 3 and 4
• 190 trap-nights per Mulgara caught

Conclusions

• A lot of new burrow dug between June and

December or burrows were not found during searches in June 2006

• Mulgara are difficult to trap in a resource

limited environment

• Digging out all burrows ensures you catch

all Mulgara

• Burrows easier to find after it was burnt

Thompson and Thompson , JRSWA , 2007, 90: 195-202

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Case study 2

Thompson and Thompson, Australian Mammalogy, 2008, 30: 65-70

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Case study 2

Methods

• 9,900 trap-nights (Jan-Feb 2007, Jun

2007) in 210ha

Results

• Very few Mulgara burrows seen
• 50 Mulgara trapped
• 220 trap-nights per Mulgara
• 395 D. rosamondae, 1 N. alexis,

27 P. desertor, 179 M. musculus, and 1,212 P. hermannsburgensis trapped

Conclusions

• Mulgara passed multiple baited traps
• n multiple nights before they were

caught

• Mulgara are difficult to trap, even in

areas of high density

• May not be living in ‘typical’ burrows
• r burrows

Thompson and Thompson, Australian Mammalogy, 2008, 30: 65-70

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Case study 3

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Case study 3

Methods

• Traps set at 25m centres for 5 or 8

nights (May 2013)

• Traps set at 25m centres
• 3,367 trap-nights

Results

• 2 Mulgara caught on nights 3 and 5
• 3 burrows recorded that could have

been N. alexis or D. blythi

• 23 P. desertor, 24 M. musculus,

30 D. rosamondae, 26 N. alexis, and 46 P. hermannsburgensis caught Conclusions

• Mulgara passed multiple baited traps
• n multiple nights before they were

caught

• Burrows are difficult to locate in

dense vegetation

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Case study 4

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Case study 4

Methods

• 1,881 baited traps, 9,740 trap-nights
• Traps set at 25m centres

Results

• 2 Mulgara caught on nights 6

and 7

• 19 D. rosamondae, 430 N. alexis,

25 M. musculus, 17 P. desertor, 196 P. hermannsburgensis caught

• 3 N. alexis burrows found

Conclusions

• Mulgara passed multiple baited traps
• n multiple nights before they were

caught

• Burrows are difficult to locate in

dense vegetation

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Case study conclusions

• searching in mature, high or dense spinifex and low shrubs resulted in

many burrows not being detected;

• it was relatively easy to misidentify burrows used by Mulgara;
• Mulgara passed multiple baited traps on multiple nights before they were

caught;

• in a high density population a minimum of 200 trap-nights / individual was

necessary to capture most Mulgara; and

• five nights of trapping was not sufficient to catch all Mulgara in an area

when traps were placed at 25m centres (16 traps per ha).

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Recommendations

• Assuming that Mulgara are living in burrows, searches to record the

presence of Mulgaras in an area should only occur when: – the height of spinifex or shrubs is less than 50cm; – the vegetation cover is less than 40%; and – the search effort is greater than two persons/hr/ha.

• In areas where the height of spinifex and shrubs is greater than 50cm and

the vegetation cover greater than 40%, then the area should be trapped instead of grid searching;

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Recommendations

• The minimum trapping effort to detect or remove all Mulgaras from an area

should be 16 traps per ha (25m centres) with traps set for a minimum of seven nights; and

• When the purpose of the trapping program is to catch and/or record all

Mulgara in an area, trapping should cease when no Mulgara have been caught within 400m of the trap for three consecutive nights.