jeff joseph -- woodworker
handcrafted furniture from sustainably managed woodlands
bats
Ten years ago, I started planting and tending a backyard orchard of about 50 fruit trees. From the outset I have been attempting to manage it organically, which in the northeastern U.S. is no small challenge, as there are a great many other life forms (mammal/bird/insect/microbe) which also would love nothing more than to devour the sweet fruits, if not the entire trees. While there are any number of systemic—and highly toxic—sprays readily available that I could be using to kill ALL (and I mean all) of the insects and disease in the orchard, poisoning the fruit prior to eating it has just never felt like a particularly smart choice (I know, call me crazy). While genocide in the orchard definitely makes it more feasible to grow a high percentage of the “perfect” shiny orbs that pass for fruits in the supermarket, such sprays also kill off most if not all of the insects, bacteria, fungi, and pollinators that colonize and/or utilize the trees in a benign or even beneficial way—the ones that are your dear friends should you try to work with nature rather than fight an endless uphill battle against it.
In any event, as I have struggled to learn about the various threats to my trees and how best to protect and nurture their delicate crops of fruit, I have made all kinds of mistakes, and have lost a number of trees over the years—to voles, deer, insects, disease, and winter cold (and if I’m going to be entirely truthful here, to a large Ash tree nearby, which I managed to fell right into my young orchard as opposed to away from it, but that’s a story best saved for another day…….).
My learning curve has flattened, but there is still a great deal that I have yet to understand about the complex ecological relationship between a fruit tree and its environment; despite this, I have managed to harvest incredible crops of heirloom fruit while using a super low-spray approach.
As my time for managing the orchard is limited, and as I have decided to forgo the “conventional” pesticide approach, I am always on the lookout for synergistic ways to encourage diversity in and around the orchard, with the goal of providing the conditions that will enhance the habitat for species that will help me out while doing their own thing—kind of like anarchist “mutual aid” in the orchard (which sounds cool at least). Insect-eating birds, pollinators of all types, companion plants that discourage pests/encourage beneficial insects/contribute to soil fertility, bacteria in compost making vital nutrients readily available in the soil, and mycorrhizal fungi in the root zone are all more than welcome in my orchard, and I do everything I can to make it a highly hospitable environment for them (the work of Michael Phillips has been invaluable in this regard; The Apple Grower and more recently The Holistic Orchard are two of the very best references should you be heading down a similar path). With another growing season on the way—with spring having just arrived—I have been making plans to expand my communal endeavor out back, and just this past week set the stage for inviting another comrade to the orchard, your friend and mine, the bat.
Bats are our only truly flying mammals (evidently “flying” squirrels are really gliding, not flying), and are tremendously successful insectivores, capable of eating up to 50% of their body weight in insects per night, which can amount to 600 or more insects per hour. It has been estimated that a colony of 100 little brown bats can devour 250 thousand mosquitoes in a single night, which is hard to even imagine (it’s also hard to imagine being anywhere in the vicinity of 250 thousand mosquitoes). This hunting takes place between dusk and dawn, so while bats have functional eyes—so are not “blind as a bat”, as the saying goes— they utilize echolocation to “see” their prey, even in complete darkness.
Interestingly, a bat “wing” is really a hand, with four long fingers connected by a thin flight membrane that connects back to their torso, and a little thumb tipped with a tiny claw (hence their classification in the Chiroptera order, which means “hand-wing”). As we’ve likely all seen after sunset, bats catch their prey in mid-flight, flapping rather awkwardly (averaging 15 wingbeats/second, at speeds upward of 20 mph) and catching insects directly in their jaws, or funneling them from their wing or tail membranes toward their mouths, which are full of tiny, but quite formidable looking, teeth. Speaking of those teeth, despite myths to the contrary, all American bats are insectivorous, so have no interest in sucking your blood, or getting tangled in your hair, and while they can carry and transmit the rabies virus, it is present in only about one in every 200 bats tested.
There are 45 species of bats in the U.S., and 9 in New York, which can be divided into two basic categories: cave bats, which hibernate to overwinter, and tree bats, which are migratory. This is a crucial distinction, as the six cave bat species, as you have likely heard by now, have been decimated by a fungal disease known as white nose syndrome. It has been estimated that 88% of all hibernating bats in our region have died since white nose syndrome was first discovered in a cave near Albany in 2006. It has been especially devastating to the Little Brown Bat (Myotis lucifugus), which was previously our most common and numerous species here in New York. Unfortunately, the Little Brown overwinters in large, tightly packed colonies in the relatively few caves suitable for hibernation in the state, leaving it nearly no chance to avoid exposure to the fungus. The Big Brown Bat (Eptesicus fuscus) is likely now our most common species, as it has been less affected due to a tendency to overwinter singly or in small groups, often in buildings instead of caves.
As soon as I heard about white nose syndrome, I knew that I wanted to try and support the bats that spend the warmer months in my area. I usually see at least a few circling my yard each evening at dusk during summer. I never managed to make it a priority until just recently, though, when I discovered what amazing insect control they can provide. I mentioned the mosquitoes already, which evidently can be a significant part of the Little Brown’s diet, but bats also eat roaches, termites, ants, gnats, flies, June bugs, garden pests such as cucumber beetles and rootworms, and major orchard pests including the codling moth, oriental fruit moth, various budmoths, leafrollers, and leafhoppers. I would gladly provide free “housing” in exchange for this kind of nightly patrol.
There is a great deal of information about bats online, including how to go about encouraging them to move to your area. Bat houses can be purchased (they are relatively inexpensive) or built, using one of any number of free plans available (I used a simple design for a single-chambered house from Northern Woodlands magazine). With one sheet of 1/2″ exterior grade plywood and a few pine 1×2 strips that were laying around my shop, I was able to build six houses for under $30!
This is a backboard for a house, with shallow kerfs to make it easy for the bats to cling to while they roost or sleep (which they do upside-down):
Here’s a completed house (use exterior-grade glue!); note that the backboard hangs lower than the front edge to provide a “landing strip”:
Here’s a closeup of the opening, which should be no more than 3/4-1″ wide—bats like tight quarters, and it helps to discourage bees or wasps from nesting, which can drive the bats away:
Last step is to paint them a dark color (black here) to absorb heat if you live in the northern part of the country, as bats prefer warm accommodations; I also added “roofing” with some metal flashing I had left from my barn roof, which will shed rain and help preserve the house:
As I wanted to encourage the bats to spend time in and around my orchard, I mounted 4 of the houses on a long pole (15-20+ feet high is recommended) which I attached to one of my orchard fence posts; it’s like a bat “ecovillage”:
The other two houses I mounted on south facing trees at the forest edge, so as to maximize the amount of sunlight hitting (and warming) the boxes:
Bats in my region generally end their hibernation in March, and begin to arrive at their summer roosting/breeding spots in April, so hopefully over the next few weeks I’ll see some fuzzy little brown (or big brown) heads poking out of their new homes, which I am more than happy to provide, rent free. Meals are also included—all you can eat. I’m hoping that this is an offer simply too good to refuse.
jeff joseph -- woodworker 
awesome we need more bats around, my hubby put up a bat house a couple of years ago, nto sure if any have found it yet, hopfully the bats will shake off the white nose fungus thing. the poor bees are introuble too, not sure what to make of it all.