Apart from the obvious exception of owls, most bird species are active during the day. But many insect species are nocturnal, and pests can damage crops in the night with nothing to stop them. That’s when attracting bats to your permaculture plot can provide a solution. All bats are night-feeders, and most are insectivores, taking insects on the wing, scooping them from the surface of water bodies, or foraging for them in trees, shrubs and ground cover, all the time using their echolocation abilities to hone in on prey with ultrasonic sound. A few of the more than 40 species of bat that inhabit the U.S. feed on nectar and fruit. But these species are beneficial to the garden as well, with nectar-feeders helping to pollinate plants, and fruit feeders eating fallen fruit that could become home to insect pest larvae.
Using permaculture design to attracting bats to your site is also beneficial to the animals as well. Not only are you creating conditions that will meet their needs, you are providing important bat-friendly habitat. Bat populations in much of the world – like many other species of wildlife – are under pressure, primarily through loss of habitat to human incursion (although many are deliberately killed by gardeners and farmers over the misguided fear that they carry rabies – they don’t). Indeed, it is estimated that almost half of all bat populations in the U.S. are currently under threat. By using native plant species and promoting biodiversity, the permaculture gardener helps to secure the future of these charming nocturnal mammals. Bat populations exist in both urban and rural settings, so any permaculturist can adopt deign techniques to attract bats to their site.
The permaculture practice of planting a wide variety of different plant species on the plot is a good way of drawing in bats – not for the plants in and of themselves, but for the wide variety of insect species they will attract. Using native species, and varieties that you may have seen frequented by bats in the surrounding area, is useful. Herbs are particularly beneficial in attracting insects, so plant a wide variety of native herbs in your permaculture design – with the added benefit of giving you a lot of choice for your kitchen. You could also utilize night-scenting plants, as these will attract moths and other nocturnal insects in abundance. There are many night-scenting flower species, but in a permaculture garden it is preferable to use cultivars that will also provide a yield. Elder, globe artichokes and verbena are all suitable choice, alongside herbs like borage and chives, and fruit trees such as apples, pears and quince. Of course, planting to attract lots of insects means that there may be times when there are quite a lot of them, particularly in the spring an summer when they breed. However, this just adds to the biodiversity of the site and good maintenance practices should ensure beneficial insects, birds and bats keep them from inflicting excessive damage to your crops.
Trees and shrubs are also hunting grounds for bats, as they provide shelter and warmth for insects, and places where insect larvae and young can live. Trees can also provide shelter for smaller, slower bats, which prefer not to cross large areas of open space for fear of predators like owls and hawks. They will use tree canopies, shrubs and hedges to protect themselves from detection. Leave dead, hollow trees on the site as potential roosting places.
Like all animals bats need a constant supply of fresh water to drink. If you have a stream running through your property, this will be attractive to bats, but even on a smaller site, adding a birdbath or even just a container of fresh water – preferably harvested rainwater, and located away from the ground so the bats are not drawn into the range of domestic cats or dogs – will draw bats to your permaculture garden. A pond will also provide habitat for aquatic insects to breed and grow. This will also attract bats, as they will predate insects resting in the surface of the pond or on aquatic plants around the edge. It is also thought that bats use bodies of water, particularly linear features such as streams, to navigate their way around their range. (Another garden feature that will boost populations of insects that bats like to eat is an open compost pile.)
Bats will generally find their own place to roost, and because they range over large areas, they tend to prefer out-of-the-way places like barns on farms or caves. However, with the loss of suitable habitat, they are increasingly being seen roosting on buildings in urban areas, or trees in municipal parks. They will also shelter during the day in small groups in hollow trees, under the bark of living trees, and under tiles and soffits in roofs. Be aware of possible roosting sites on your property and do not disturb them if bats choose to use them. You can also provide shelter for bats by installing bat boxes on your site. Similar to bird boxes, a bat box can be purchased, but is fairly easy to assemble from recycled timber. Just make sure the timber has not been painted or treated with wood preservatives. You can place bat boxes on tree trunks but these tend to be lass favorable spots as they are not as warm as boxes placed on the sides of buildings or on dedicated poles. With both these latter locations, make sure the bat box is out of the reach of domestic animals, and in warm but sheltered aspects – a southerly or westerly is best. Avoid placing boxes too near doors and windows, as the bats will be disturbed by the proximity to people. You also want to place the boxes in locations that are inaccessible to snakes, who are, along with birds or prey, the bats’ main predators. Boxes will ideally have a small opening with a platform below it that juts out for the bats to land on.