Forests for the Bats Part III: Foraging Habitat
Bats are not something that you should be afraid of, but to nocturnal insects there is no greater danger. An individual bat will eat thousands of insects each night! This is good news for humans who want less insect pests, but means that bats need good foraging habitat to satisfy their voracious appetites. In Forests for the Bats Part I we detailed how bats use forests, and in Part II we discussed the protection and management of roosting and hibernation sites. Foraging habitat is also very important and can be improved on any property, from a large forest tract to a suburban backyard.
Foraging habitat must have an ample insect population and enough space to maneuver while hunting. These typically occur together because forest openings will allow more herbaceous vegetation to grow, which will increase insect diversity and abundance. Bats often forage in openings created by tree mortality or timber harvests, where there are flushes of herbaceous and young woody vegetation that yield high insect numbers. Linear features like roads, trails, and forest edges also provide good foraging habitat because they are easy to travel and often have healthy herbaceous layers.
Bats also require water near their hunting grounds. Amazingly, they drink while flying, and thus need ponds or streams that are open enough to allow access. Water bodies also often support high insect densities, so they are doubly valuable for foraging bats. Encouraging native vegetation around streams and ponds rather than managing them like mowed lawns will increase their utility as foraging habitat for bats and also dramatically improve the quality of the water.
Managing a forested area for ecological health and productivity will also improve its quality as bat foraging habitat. A timber harvest that removes most or all of the overstory trees may look bleak right away, but within a year or two it will develop a thick, diverse layer of herbaceous and woody vegetation that will provide excellent foraging habitat for bats. A forest thinning cut, where some trees are removed to increase the growth of remaining overstory trees, will also be hugely beneficial to bats. It will increase the light reaching the forest floor, thus stimulating understory growth and boosting insect populations, and will make the stand easier fly through. Thinning a stand will also increase the light that reaches each tree, improving potential roost sites. Similarly, prescribed fire will improve understory vegetation and clear some midstory trees. A fire may consume existing snags, but will likely create new ones, resulting in a stand that’s improved for both foraging and roosting. These forest management techniques will also increase the stand’s health, improving its value for other wildlife and for a landowner interested in selling timber.
If you don’t own forested land and have no ponds or streams on your property, you can still contribute to bat foraging habitat by planting native flora. Non-native plants are commonly used in landscaping, but they don’t support many (if any) native insects. Bats need robust insect populations to survive; in areas where there are few native plants there won’t be enough food. Consider replacing non-native ornamental plants and turf with native vegetation. This will help feed the bats, and will also improve your property for other wildlife and can reduce your stormwater footprint.
Bat foraging habitat can be improved in forests, farms, and neighborhoods by promoting healthy communities of native vegetation. If we want bats around to eat pests that cause damage to agricultural production, timber, and human health, we need to support their populations with native plants that will feed native insects. To learn more about forest management techniques for bats and other wildlife, visit Forests for the Bay, and for guidance on promoting or planting native vegetation, visit the Alliance’s Native Plant Center.