DRB Meeting February
Speaker Tony Hodge, is a zoologist and bat care volunteer at Kanyana Wildlife. Tony began by telling the audience that bats were originally thought to be rodents or primates but amazingly, their closest living relatives are horses and rhinoceroses! There are two main types of bat: fruit bats and insectivorous micro-bats, which include Horseshoe Bats, Leaf-nosed Bats and Evening Bats. Fruit Bats generally live in the tropical northern areas, and micro-bats live in southern areas. Australia has 90 of the world’s 1300 bat species.
Photo: © T Hodge
Bat research has increased in recent years due to technological improvements in recording their sounds. Bats use echolocation to locate their prey. Echolocation frequencies are different between species, and because producing the sound in the larynx is quite energy-sapping they tend to co-ordinate it with a wing-beat. As they approach their prey the number of calls increases to improve resolution, called a ‘feeding buzz’.
Bat wings are highly-developed structures and the fingers on the wings give them better control and agility than birds. Bats are very smart, social creatures, often living in large colonies. Their vision is good, despite the ‘blind as a bat’ myth, using sight to hunt for prey on tree trunks and on the ground. Their ‘talking’ is loud and obvious.
Tony described and showed us four commonly-occurring bats from the Perth metropolitan area.
Lesser Long-eared Bats (Nyctophilus geoffroyi) hunt just above the ground and in the tree canopy. They are very agile, but fly quite slowly, have enormous ears and fine-tuned echolocation, and prey on moths, crickets, grasshoppers and flightless insects. They are often preyed on by cats.
Photo: © T Hodge
White-striped Free-tailed Bats (Austronomous australis) hunt above trees preying on large beetles and moths. They fly fast but are not very manoeuvrable, can also hunt on the ground, have big ears and live in tree hollows. They move south in summer to stay cool.
Southern Forest Bats (Vespadelus regulus) are tiny, with adults weighing just 6 grams! They are determined and grumpy, eating bugs, moths, crickets, ants and cockroaches, and live in tree hollows and houses.
Gould’s Wattled Bats (Chalinolobus gouldii) are the most common bat seen by carers as they easily dehydrate. They fly at medium speed in zigzag patterns around tree canopy, and eat bugs, moths, crickets, ants and cockroaches, and have seemingly insatiable appetite! They nest in tree hollows, are family-oriented and the adolescents frequently get lost.
Photo: © T Hodge
Threats to bats include pesticides (which kill the bats’ food), habitat loss, and climate change (bats are very sensitive to heat, some dying above 320C). Human attitudes to bats, such as seeing them as evil, crop pests, and disease vectors also endangers them.
In fact, bats eat insect pests, pollinate and disperse seeds for many tropical trees, and provide guano for fertiliser. Bats are very long-lived (up to 42 years), have amazing biochemical mechanisms, including immune systems which shut down quickly, and can hibernate to save energy. They are being used in research into cancer, autoimmune diseases and ageing. They are amazing and cute, so we need to save them!