Northern Suburbs Branch, 20 November 2024
Many of us know David Pike from his long association with the Wildflower Society of Western Australia, conducting weekly Saturday morning walks and monthly plant identification table at the Northern Suburbs Branch meetings. He also has a keen interest in photography, especially of insects, and, as we found out, he has now included bats in his vast knowledge.
David explained that even though bats may look as though they are related to rodents, they are more closely related to whales, lions and cows.
There are two separate groups of bats: fruit bats, mostly found in our tropical north and micro-bats, mostly in the southern part of Australia. Each is thought to have evolved separately.
Even though WA has 37 species of bat, Perth has four main micro-bat species:
- Lesser Long-eared Bat (Nyctophilus geoffroyi)
- White Striped Freetail Bat (Austronomus australis)
- Southern Forest Bat (Vespadelus regulus)
- Goulds Wattled Bat (Chalinolobus gouldii)
Bats use ultra-sonic echolocation. The soundwaves bounce off objects, and the waves that bounce back tell the bat a lot about the object, such as how far away it is, its texture, shape, size, and whether it is moving or stationary. Some bats have special features to help echo-locate, such as long ears for better hearing or growth on their nose called a nose leaf, which focuses on the outgoing sound.
Bats consume insects, many of them agricultural or disease-causing pests. They can eat up to 500 mosquitos per hour. Bats also play a role in pollination of a variety of plants. Most bats go into torpor over winter as there are fewer insects around.
The Conservation Council of Western Australia (CCWA) says more than half of the state’s species are in decline, or their status is unknown, due to a lack of research. Kelly Sheldrick ran a CCWA citizen-science program from November 2023 – February 2024, taking grassroots bat-watchers under her wing to help monitor the state’s population and restore bat habitats. Eighty-six trained volunteers recorded 2,534 bat calls in the 5 regions surveyed.
David demonstrated using the bat detector he had brought to the meeting, the Echo Meter Touch 2 from Wildlife Acoustics. He had used this as part of the Citizen Science project at Koondoola Bushland.
A number of our members then ventured out with David around Star Swamp to try and detect bat sounds. They had limited success as it was well past dusk when bats were most active.
Willy Dadour