Feature, News from the Field

Ghost bats, crocodiles and another 161 species detected in Gulf of Carpentaria survey

26 Sep. 2023
Damien Cook/AWC

By Melissa Christi, Field Ecologist

Quietly boasting some of the most beautiful lands in Australia, Pungalina-Seven Emu Wildlife Sanctuary is bounded by the Robinson and Calvert Rivers in the Gulf of Carpentaria. Here on Yanyuwa and Garawa Country, our small team of field ecologists and volunteers, led by Senior Wildlife Ecologist Dr Eridani Mulder, undertook the targeted Ecohealth Surveys for 2023.

The survey team. From left: Field Ecologist Melissa Christi, Field Ecologist Sanne Boland, Senior Wildlife Ecologist Dr Eridani Mulder, Volunteer Greg Waddell, Field Ecologist Jake Barker, and volunteer Damien Cook. Front: Volunteer Elaine Bayes. Melissa Christi/AWC
The survey team. From left: Field Ecologist Melissa Christi, Field Ecologist Sanne Boland, Senior Wildlife Ecologist Dr Eridani Mulder, Volunteer Greg Waddell, Field Ecologist Jake Barker, and volunteer Damien Cook. Front: Volunteer Elaine Bayes.

Over three weeks, we explored grassy savannas, trundled through several types of Eucalyptus woodlands, trudged through lilies and mud around swamps and wetlands, toiled in Callitris patches, and teetered across sandstone scree slopes. In total, we completed 61 targeted bird surveys, four wetland bird counts, 11 wetland condition assessments, a Ghost Bat (Macroderma gigas) roost count, two nights of microbat trapping, a feral herbivore survey, and two Cypress Pine surveys.

Senior Wildlife Ecologist Dr Eridani Mulder takes measurements of a Pygmy Long-eared Bat (Nyctophilus walkeri). Melissa Christi/AWC
Senior Wildlife Ecologist Dr Eridani Mulder takes measurements of a Pygmy Long-eared Bat (Nyctophilus walkeri).

During the first week at Pungalina-Seven Emu, our team were able to assist Professor Vic Galea from the University of Queensland. Professor Galea is in the process of trialling a new fungal bioherbicide method called Di-Bak for parkinsonia (Parkinsonia aculeata), a thorny plant recognised as a Weed of National Significance. If allowed to grow unchecked, it forms dense thickets that outcompete native vegetation and clog waterways, altering the landscape.

Professor Galea and Assistant Sanctuary Manager Matt Warr worked with the science team to locate parkinsonia mapped in 2014 and 2018 in aerial surveys and uncover any new Parkinsonia locations. While out there, they began the trials using a special device to drill into the trees and insert capsules of Di-Bak directly into the trunk, where the fungus will spread through water amongst the roots to other nearby trees.

A Saltwater Crocodile (Crocodylus porosus) sunbathing on the banks of the Calvert River. Damien Cook/AWC
A Saltwater Crocodile (Crocodylus porosus) sunbathing on the banks of the Calvert River.

Most of the Parkinsonia locations were along the mighty Calvert River, and it was a thrilling experience seeing large Saltwater Crocodiles (Crocodylus porosus) lazily sunbathing while White-bellied Sea-Eagles (Haliaeetus leucogaster) soared overhead. One afternoon while boating to the islands in the river, we heard the chattering cries of Black Flying Foxes (Pteropus alecto). A small colony had made camp in the mangroves! This was a delightful discovery as the species had not been seen at Pungalina-Seven Emu for a few years.

This felt like a good start to the Ecohealth Surveys, and we began our series of targeted riparian and savanna bird surveys. Breaking up into two teams, we spent the following two weeks straining ears and eyes to look for our indicator species (previously recorded species) across 62 sites.

Thanks to Matt and Amanda and their volunteers, we had road access to most of our sites and were treated to the full spectacle of the country up there from great stretches of Melaleuca swamps (thankfully dried out) to Pandanus-lined creeks carving their way through golden grass-covered savannas.

A personal favourite would have to be the turkey bushes in full bloom along the road, dripping masses of magenta blossoms with grevilleas overhead, almost drooping with huge orange flowers full of sweet nectar.

Savanna eucalypt woodlands. Melissa Christi/AWC
Savanna eucalypt woodlands.

Between targeted surveys, we completed the rest of the Ecohealth surveys both above and below ground.

Using thermal scopes, our team disappeared underground looking for bats. Pungalina-Seven Emu has remarkable, deep limestone caves, kept at a comfortable ~30°C year-round. These warm, humid caves are key habitat for Ghost Bats – the only carnivorous bat in Australia. Being in complete inky darkness, dripping sweat, and watching Ghost Bats through the thermal scope reduced to orange-red orbs was an incredibly unique experience. Throughout the large caverns, rain has dripped through ceiling cracks to deposit mineral-rich droplets. Over aeons, these droplets have formed into glittering stalagmites and stalactites.

Ghost bat (Macroderma gigas) roosting in a limestone cave. Gina Barnett/AWC
Ghost bat (Macroderma gigas) roosting in a limestone cave.

During the surveys, we were on high alert to detect as many incidental species as possible and ended the trip with a respectable list of 163 different species of birds, mammals, and reptiles. Seeing a Northern Nailtail Wallaby (Onychogalea unguifera) bounding over the Calvert River floodplain, wrinkly Arafura File Snakes (Acrochordus arafurae) in crystal-clear creeks, and Purple-crowned Fairy-wrens (Malurus coronatus) flitting through Pandanus crowns, are just a few highlights from a busy, albeit very rewarding trip.

Undertaking a large cluster of surveys like this would not be possible without the help of our volunteers and supporters. These gifts of time and financial support enable us to continue the critical task of conserving the incredible flora and fauna we are so lucky to have in Australia.

Read more about previous Pungalina-Seven Emu Ecohealth Reports

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