UPDATE APRIL 2024: WE HAVE RECENTLY PURCHASED A HANDHELD BAT DETECTOR WITH THE SUPPORT OF A STATE NRM GRANT AND WILL BE CONDUCTING REGULAR WALKS THROUGH JIRDARUP.
Bats in Jirdarup @4 December 2023
Are there bats in Victoria Park and South Perth? The answer is yes. Are there bats in Jirdarup? Some.
Two species of bat were identified in Jirdarup using a bat detector installed in the bushland for 6 days, from 17 November 2023 by local bat enthusiast Ry Beaver. The detector turns on at night and is triggered by ultrasonic noises that can be interpreted in a spectrogram. The frequency of sound waves, ie vibrations per second, used by bats averages 50 kilohertz (50kHz) compared with the frequencies audible to most adults which range from 3 up to 18kHz.
This was a particularly hot and dry period with daily temperatures over 35° compounded by a small fire in the bushland on day 3.
The initial results from November showed 5804 recordings of high frequency sounds creating much excitement. However, analysis showed that all but 120 were other noises – mostly crickets. Within those 120 calls, about 8 could have come from bats.
Ry was fairly confident he detected Gould’s wattled bat (Chalinolobus gouldii). This is one of the most common bats in Australia. After consulting with a fellow bat enthusiast, the other calls were confirmed to be from a South-western Freetail bat (Ozimops kitcheneri).
An earlier observation when it was cold and wet in June 2023 detected a long-eared bat (Nyctophilus sp.). For long-eared bats, the species cannot be identified from the calls alone – the bat must be seen. These bats have higher pitched calls, are very acrobatic flyers and feed in the canopy.
Interestingly there was no record of the White-striped Freetail bat (Austronomus australis) which is very common throughout Australia and has been recorded in nearby Carlisle. These bats can be heard by people with good hearing with their high pitched ‘zing, zing’ sound. They fly very fast, often quite high (over 50 metres) with a low frequency call (11-13kHz) for a bat that goes a long way.
In short, three bat species have been detected passing through Jirdarup:
- June 2023: 1 long-eared bat (Nyctophilus sp.)
- November 2023: 6 Gould’s wattled bats (Chalinolobus gouldii)
- November 2023: 2 South-western Freetail bats (Ozimops kitcheneri)
The White-striped Freetail bat (Austronomus australis) has been detected in the next suburb.
Given the low call numbers, we hypothesise the bats were transiting over this portion of the bushland during the survey – not necessarily roosting or foraging.
Please send us any other observations of bats in and around Jirdarup and we will make sure they are reported to the Bat Monitoring Program being conducted by the Conservation Council of Western Australia.
