Gardening
Bats

Anything that eats mosquitos is OK by me, so I have a special fondness for bats.

Some of us have been conditioned by childhood stories about night flying , blood sucking mammals and are quite horrified by the idea of meeting a bat "face to face", so to speak. In fact bats are intriguing and useful creatures (except the blood sucking ones, I'll concede that they are intriguing and a sort of creepy nuisance, but they don't live in Australia).

In fact bat prejudice has resulted in mass destruction of their numbers and habitat, including shooting, poisoning and blasting of caves. Bats also suffer from removal of old trees with hollows and from pesticide use, because they are insect feeders.

It is this feature that makes bats so useful. Bats eat enormous numbers of insects. Almost all Australian bat species are insect eating, and may eat up to 50% of their own body weight each night, during their active season.

Bats do not have some of the adaptations of birds, such as "spongy" bones with many air pores (for light weight). Bats therefore have to cart around a heavy mammalian skeleton. Because they already have a high body weight, they can't carry around a big dinner too. Consequently bats gave evolved a short gut with rapid transition times (around twenty minutes from ingestion to voiding). Presto two desirable consequences (for organic farmers) - one is lots of insects consumed another is the nutrient rich droppings!

Unfortunately for the bat the nutrient rich droppings have lead to must habitat destruction as the material is extracted and bat guano should be regarded as a suspect material for environmentally aware gardeners.

If you have bats flying overhead, you'll get some guano anyway.

And a few thousand less mosquitos every night.

I have watched bats emerging from air vents in the roof of my home and flying around the back porch consuming insects attracted to the light. After enjoying their fill for twenty minutes or so they returned to the vents only to find they didn't fit through. They would slowly squeeze in, sometimes taking the best part of five minutes to ease their way between the vertical grill.

Occasionally, when moving boxes in the shed loft I would uncover one, or they would fly into the house via a chimney or open door. They are very delicate and gentile and remind me very much of a mouse with wings. Do not touch them with your hands or pick them up lest they die of shock and yes, they can bite, but only if they have to - certainly not if they have a way out. If they come into the house, turn the lights off and open doors and windows and they will leave when they smell the fresh air.

Some bats feed on flowers or nectar, such as the red flying fox, or fruit.

You can encourage insectivorous bats by placing bat boxes in trees. There are various designs but a common one is a wooded box about 20 cm cube with no floor and fine mesh wine stapled to the top (on the inside) for bats to cling to.

Did you know

Bats occur in every region except the Arctic Zone and some remote islands.

They are the only mammals capable of sustained flight.

There are about 900 species of bats in the world, more than in any other mammalian order except for rodents, and bats probably out-number rodents in total abundance.

Bats make up almost 25% of the mammalian species of Australia.

The largest bats in the world lives in Java and may have a wingspan of more than one and a half metres and a body length of almost half a metre.

The smallest bat in the world is the Kitti's hog-nosed bat of Thailand. It is only 3.3 cm long and weighs about 2 grams, one of the worlds tiniest mammals.

Most insectivorous species target their prey by echolocation - the emission of high-frequency sounds that are reflected back as echoes from surrounding surfaces. The bat can tell the position, distance, and the nature of objects by their eco signal.

Bats are not blind - most of them can see reasonably well.

Fruit bats use vision rather than acoustic location and only one genus has evolved an echo-location mechanism, and it is used only when it is dark.

Some species of bats are migratory and move up to 1600 km between summer and winter habitats.

One Australian bat eats small fish, which are caught on the wing as the bats fly over the water surface.

Most southern Australian bat species hibernate during the winter months.

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