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Tx-VHF Transmitters (Model F1840) were fitted to ten echidnas in 2018 and three more echidnas were tagged during the study, in April 2019. These transmitters were manufactured by Advanced Telemetry Systems. They have a battery life of 787 days and send 40 pulses (between 150-152MHz) per minute (ppm).

Echidnas were found by searching throughout the study area (around the Folwers Gap Homestead) while the animals were foraging or moving. Search effort was evenly distributed across the entire study site. Once echidnas were located, spines on the acnestis were clipped to ~5 mm long, and a 20 g transmitter was attached using a fast-setting non-toxic epoxy resin (Gorilla Glue Inc. USA). The transmitters did not exceed 5% of the smallest echidna’s body mass, which is the recommended limit [25]. Each echidna was weighed upon capture and categorised as either juvenile (<2 kg) or adult (>2 kg) [26]. Echidnas were identified as females if there was an absence of hind-leg spurs [17] as other sex-specific characteristics such as pouch development in females, or penis protrusion in males were not reliably identified [17, 27].

Over a 2-year period, thirteen adult and sub-adult echidnas were tracked to calculate home range of echidnas at Fowlers Gap. The echidnas were numbered: E1-13, with number 1 being the earliest tagged, on 16 March 2018 and number 13 being tagged last, on 27 April 2019. Of these, E1, E2, E4, E5, E6 and E13 were reliably identified as females, based on the absence of hind leg spurs [17]. Weights of echidnas, at the time of capture, ranged from 1.1–4.8kg. E1 and E4 were found dead on 29/11/18, E7 and E8 were found dead on 22/2/19. Although it was not possible to determine exactly when the animals died, the amount of decay suggests none had been dead for longer than a few weeks. No signal could be detected from E2 or E5 during the 2019 but no carcasses were recorded so it is assumed that their tags failed early. No signal was located for E9 and E12 during September 2019 (assumed to be tag failure). E13 lost her radio tracker sometime between May and August 2019.

Echidnas 1–10 were located regularly during March, April, May and November 2018 part of a prior study. E3, E6, E0, E10, E11, E12 and E13 were located regularly during March, April and August 2019. Echidnas were located daily using a VHR receiver (ATS R2000) and a handheld 3 Element Folding Yagi Antenna (ATS). Searching commenced on hills or creek banks near the last recorded location of the animal and continued until reliably located the echidna by either: physically observing the echidna or finding a pin-pointed signal above a burrow. Once located, the foraging or resting site was marked with yellow flagging tape and the geographical coordinates were obtained using a Garmin handheld GPS with at least 4 m accuracy. If a signal could not be located after checking from all peaks in and around the study area, it was assumed that the echidna was buried too deep or was hiding in a gully or rock cave where the signal was blocked.

As with previous echidna home range studies, [8], independent locations were determined by:

All locations of echidnas not in shelters, or

All locations of echidnas in shelters, unless they have previously occupied that shelter with no evidence that they have left the shelter and then returned.

Previous research has suggested when using statistical techniques to predict home range, at least 15 independent data points were required to best reflect the true home range of the animal [15]. Hence, animals with less than 15 independent data points (E7, E8, E12 and E13) were not used for home range analysis.

This study was undertaken on research permit (Approval number: 18/3B) issued by the UNSW Animal Ethics Committee, and NSW National Parks and Wildlife Service scientific license number: SL102050.

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