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Posted: Sun Feb 8th, 2004 07:10 pm |
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just got back from a mini-seminar on bats and swallows, given by the Thurston County "Stream Team", so I now have a BCI type "simple economy summer box" to hang as soon as I paint/stain it, and air it out :grin: .
but it got me to thinking about solar gain in northern climes -- this particular area, being in the "river drainage" off Mount Rainier, gets colder in the winter and hotter in the summer, than most of the rest of western Washington.
we designed our house as a modified passive-solar, with provisions to put in active solar later, so we did a lot of research on that :roll: .
so at last my question -- has anyone affixed Mexican ceramic floor tiles (painted matte black) to the front and/or sides and/or roofs of their bat boxes, as additional thermal mass? :idea: and if so, what was the result?
alternatively, has anyone affixed rocks or slate to their bat boxes?
here, we have about an acre in an area of mixed prairie, fir trees, oak trees, Scotch broom-overgrown lots, pastures for dairy cattle, horses, and egg-farms, and houses on fairly large lots; with the Centralia power canal just off our north boundary line, the river about 1/8 mile beyond it, and miscellaneous swampy land in between.
we know we have bats in spring, summer and fall; we can see them, and occasionally I can even hear them if I'm walking out in the yard then -- we also have redtailed hawks, golden eagles, and bald eagles nesting in the trees just to the north of us, along the banks of the canal.
we THINK we might have had bats overwintering for several years in our open-ended large storage building (50 x 60 with the opening to the east), and we are now planning to put a door on that, potentially excluding the bats (we can put a vent in for them, of course, but aren't certain how we can design it to admit bats yet exclude paperwasps and "ground bees"); we also aren't sure if bats would care to stay after we put doors on and a solid floor in (and pursue hobbies during the day, into the evening)
the building faces east, has a garage door on the south side, otherwise plain T1-11 siding everywhere else, is on the north end of the lot with
one big oak to the south, neighbors' trees to east and west, one big fir (with a lot of branches missing due to a huge snow and wind storm a couple of months ago) to the southeast (and it's unheated, has no insulation internally)
would welcome any suggestions -- I've read much of the information on bats and bat-houses available on the internet.
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Dave Miller
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Posted: Mon Feb 9th, 2004 07:43 pm |
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I have attached a large flat rock (painted black) below the entrance to my nursery-style bat house (http://bat-house.freeservers.com/mybathouse/index.html), which is also in western Washington (Camas). I can't say whether this has helped or not, as I have had very few bats use the house. I think I'm just too far away from a large body of water. Also over the last few years the blackberries have gotten away from me, making it very difficult to get to the house for maintenance. This fall I cleared a path to the house and discovered a number of paper wasp nests in it, which I'll clear out in the next few days. (By the way, does anyone know if bats and wasps "battle" over a roost? It seems that they like similar roost spots. If they do battle, who generally wins?)
My thought with placing the rock below the entrance was that the morning sun would warm the rock, and the heat would rise into the house. It also gives a bit of a slope to the landing area (vs. purely vertical). I have a piece of 1/2" wire mesh over the top 6" of the rock, as a landing area. I carefully filed off any sharp edges on the mesh, and also painted it, so it has no sharp edges which might tear a wing.
I believe the rock does warm the house in the morning, though I have not taken temperature measurements. I put a piece of 3/4" rigid insulation on the inside of the roof (covered with veneer), to contain some of the heat, and also to keep the roof from getting too hot (this style of house has an "attic" which is supposedly attractive to nursing females with pups).
The only downside to this rock at the entrance is that I cannot see into the first two crevices from below. But that is not a big deal.
As for your ideas with tile or stone, it would be great if you could experiment with different placement of the tile/stone to see what the bats prefer - below the entrance, on the front, on each side, on the roof. In our area (marine west coast) I think we are trying to mimic exfoliating bark on large dead trees, so anything that looks or feels like that would be of interest to the bats (thus the recent rise in popularity and occupancy of "rocket" style houses).
As for placement, I believe buildings rank first, followed by poles. Houses in trees, even with missing branches, do not do well. Perhaps if you can find a large dead tree, that would be worth a try. But I have no idea how you could get a bat house up in a large dead tree safely, unless it died recently. A predator guard on a pole or dead tree is a good idea.
Keep us posted!
Dave
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Mark Kiser
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Posted: Mon Feb 9th, 2004 07:51 pm |
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About 5-6 years ago a Research Associate (in OR or WA) in BCI's Bat House Project tried ceramic tiles on the front of a few boxes. These boxes also had a piece of plexiglass on top of the tiles, but a 3/4 inch dead air space was left between them. He attracted a few bats. Not sure what size tiles he used.
BCI tried this same technique in British Columbia using 4 x 4 inch tiles, the thin kind, standard size for kitchens/bathroom walls. Only 1-4 bats used the two boxes we tested, one with just tiles, the other with tiles and Plexiglass. We put data loggers into these houses, and they just didn't hold the heat into the night like we thought they would. Probably these tiles are too thin.
It's likely that thicker, dark tiles on the front and even tiles inside a sealed-off chamber would be an advantage over a standard box. Just a bit heavier, though.
It would be worth trying the thicker Mexican tiles. Let us know what kind of luck you have with them.
Sincerely,
Mark Kiser
BCI, Bat House Project
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Posted: Mon Feb 9th, 2004 10:01 pm |
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thinking more overnight; if I can find sufficient material, I think I'll also try constructing a mini-solar panel as the "roof" of a deeper (3-5 crevice) bat house, using glass rather than Plexiglas, tilting it at 60* which is about standard for our area, sealing it well, maybe including either a black-painted piece of corrugated metal, or black-painted tiles
I'd like to mount the bat house(s) on our house, but there's a problem; we have a Lindal/Justus type cedar house, with all-glass on the directly-south-facing (tall) side; the top story is recessed about six feet from the main floor on the east and west sides, so there's no unbroken 12 to 15 foot wall to mount the box upon ! there's a deck too close to the eaves of the main floor (we have cats who catch anything up to blue-jay size), and the eaves of the paired dormers on the top story are only about six feet above the (30* sloping) main floor roof below them -- the only unobstructed areas with sufficient "drop" would be on the northwest or northeast corners of the house, and those are 1) shaded half the day and 2) too close to overhanging oak tree branches
so the bat habitats will have to go either on the east-or west-facing peaks of the uninsulated, unheated storage building, or on posts which are VERY sturdy (we get 70+ mph gusty winds here in the river valley, up to a dozen times a year; everyone has gone to mini satellite dishes because the TV antennas blow down repeatedly)
oh, did I mention retired on limited budget? am going to beg for scraps from the local hardware stores and construction sites ...
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"Candy"
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Dave Miller
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Posted: Wed Feb 11th, 2004 07:20 pm |
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I don't quite follow what you have in mind as far as solar gain features, but keep in mind that you don't want the house to get too hot on those warm august days. Bats like a pretty constant temperature, and will need to "escape the heat" on really hot days. I believe recent research shows a preference for tall houses, where the bats can move up and down to find a temperature zone to their liking. Many bat houses feature a small vent on the front or sides to allow some air circulation at the lower part of the house.
Regarding limited budget, I built my bat house entirely from scraps left over from a cedar fence project, plus 1x12 pine shelving, and an old road sign. The only thing I bought was the screws to connect it together, four lag bolts, and two metal straps to secure the top. It is mounted on an old power pole that I scrounged up (the creosote smell on hot days may be another factor in the low occupancy rate?). This whole assembly is incredibly heavy and strong, and is not at all affected by the winds, which have been up to 55 mph since the house has been up. Getting the pole in place by hand is not all that hard if you follow the procedure that I did, which I can describe for you.
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Posted: Wed Feb 11th, 2004 08:28 pm |
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what I was thinking about, in proposing a mini solar panel for the next bat house I build, was the situation where the house is mounted on the east-facing gable of the storage building, thereby shaded from 1 PM on (and I'd build a nearly-square "nursery" type house)
the concern here is to warm the bat house sufficiently during morning hours (it may also be shaded from about 11 to 11:30 by the tall fir tree located about 50 feet southeast of it) that it will stay relatively warm all day and into the evening hours -- we might have a week of 100+ temperatures in August, but this area tends towards morning fog in summer, on days that turn out to be clear (not to mention that it rains in August too, this *is* the Pacific North Wet :grin: ) and we're about a hundred miles north of you
I like your idea of making it taller than the 28" BCI model we built at the workshop, and incorporating ventilation slots (the BCI model features one even though the workshop leader says those aren't strictly necessary for the Olympia area -- we're some 15-20 miles inland up the river from there, so our temperatures fluctuate more than theirs do, next to the Sound)
my son says they have lots and lots of scrap 2x4s at the power equipment company where he works; the catch is that I'd have to disassemble pallets to get them ... not a problem, got crowbar, got Makita, got bow saw :wink:
I'm also going to be on the lookout for strandboard/waferboard -- have heard that MEDEX is good, but what about other types? my concern would be toxic or outgassing solvents or glue ...
reasoning here is, to increase the "thermal mass" and possibly retain the heat for longer periods -- get a quick warm-up in the morning, then hold the heat through using dense or thick material further "back" in the house (with the hope, also, of attracting LOTS of bats who will heat it up themselves) -- we have lots of rock and sand available, since much of this area is basically glacial till, covered with a very thin layer of topsoil
we did a pretty good job on our people-house -- it's always quite a bit warmer than ambient all fall, winter, & spring, and considerably cooler in summer, due to 6-inch-thick solid cedar t&g logs, windows to east and south, virtually unbroken wall to the west (so the heat percolates through slowly, keeping us warm at night)
however, if we put a bat house on the west-facing gable of the building, we will need to be careful about temperatures, since it would get full sun from about noon or 1 PM until perhaps an hour before official sunset (it's shaded by the neighbor's garage and by tall firs several hundred feet away to the southwest which block the horizon)
now if we could only "average out" the solar gain between houses mounted on the opposing gables !
power poles seem to be at a premium around here (the power company actually RAN OUT of them this last winter since so many broke or split in snow- and windstorms), so I'm on the lookout for a dead tree that I can beg from a landowner, will be figuring out how to mount it since we have the usual dry rot and carpenter ant problems, it can't go directly IN the ground (I like Marvin Mabry's pivot-pole idea, gotta figure out how to make it sturdy enough to deal with our whistling winds)
time to go prowl around and see what I can salvage; we're in the middle of our "false spring" that comes around about this time every year, and since I'm seeing a lot of insect hatches, it could be that bats start showing up soon, even though I notice the grass is still white with frost most mornings
thanks for anything else you guys come up with ...
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"Candy"
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Dave Miller
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Posted: Wed Feb 11th, 2004 10:55 pm |
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Does your house have a chimney? If so that can be an ideal place to mount a bat house. I helped some friends put up a bat house on their chimney. They had bats living in their attic, and were about to exclude them. The bats readily moved into the bat house. However be extra careful if you try this, climbing around on ladders on top of roofs can be very dangerous.
I believe there is some data on the NABHRP website on using sand for thermal mass. Seems like that might be a good idea in your case.
I would stay away from strandboard/waferboard due to outgassing concerns. Most bat houses are exterior plywood on the outside. Mine is cedar on the front, back, crevice walls and roof, with pine on the sides because that is what I had laying around. The pine seems to require repainting every 5 years or so. If I were to do it again, I would glue together cedar edge to edge to make the sides. I put saw cuts on all the interior surfaces about 1/4" apart. This took a while (the house has 7 crevices) but I think was worth it. Cedar fence board is pretty cheap and lasts a very long time.
I don't know of any bat house designs that use 2x4's, but I'm sure you could come up with one. If they are on the exterior they will need to be protected from the weather somehow (e.g. painted & repainted). Probably better to stick with something more weather-resistant. One thing to watch is the thickness of the front - if it is too thick, the sun's heat will not penetrate into the house. However this also tends to keep the heat in. Again think "exfoliating bark" for the front, and "hollow tree" for the interior crevices.
If you have a lot of land, you could always make a live tree dead :-)
I've also wondered about making a strong pole from plastic pipe and concrete. I'd probably go with 4" or larger black sewer pipe, which wouldn't be quite as ugly as white PVC or gray electrical conduit (though you could paint them, or let a climbing vine grow up them). Two pieces would make a 20' pole - put 4' into the ground, that would put the bottom of the house about 14' off the ground, which is a good height. Glue a cap on one end, fill it with concrete, then cap the other end after the concrete dries. You might want to put your mounting hardware on first so you don't have to drill into concrete. A piece of rebar down the middle might be a good idea too, especially 3' to 6' from the bottom, where the pole will flex in the wind at the ground level. I'm just thinking off the top of my head here. I put up a basketball backboard on a pole, and it required the (4" thin steel) pole to be filled with concrete. Makes for a pretty strong (and heavy) pole. It might be worth trying sand first instead of concrete, so you can get an idea if this would work. Sand would allow you to undo your work if it looked like this wouldn't fly. You could also make two poles if just one is too flimsy. The pivot-pole would be a nice feature for maintenance, though a pole full of concrete with a 40 lb. house on top might be a bit heavy.
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Posted: Thu Feb 12th, 2004 12:51 am |
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oh yes we have chimneys -- two long metal ones; one from the basement through all three levels, one from the main floor -- however, since they ARE black metal, and uninsulated, I think it might get a tad too warm for bats there, since we burn wood most nights during the winter -- they come up through the center of the house, so they top out at roof height, here again, no ten+ foot "launch zone" ... and since we live adjacent to a private airport, we are alert to takeoff and landing requirements ...
local lumberyard had a pallet faced with really OLD strandboard, well watersoaked, that they were going to let me have -- makes me wonder how long it takes for the outgassing to stop, as the face wood was soft, almost like fleece, seemed ideal for bats to cling to -- the "expert" here was examining a nursery-box made entirely of strandboard, with multiple layers of black stain; felt the stain "sealed" the surface well enough
their other free-for-the-taking pallets have good 1x4s and 1x6s --- good in the sense that they are roughsawn; I'd think they'd make pretty good internal partitions if they were set vertically edge to edge -- a carpentry freak would probably "biscuit" them, but I'm not a purist -- also would prefer to keep the glue/caulk on the outside of the bat house, not inside
as for the 2x4s, I was thinking of these more for the back and the sides, maybe in a board-and-batten arrangement to stop any stray air leaks; I agree, you want the early-sun-facing surface reasonably thin so it heats up quickly; I guess some people put tarpaper on the front, or galvanized metal painted black; I snickered at first when I read that some were using spray-on truck bed liner, but on second thought I realized that it's durable and does a good job protecting surfaces from the weather
I'll have to think about the posts (and about our neighbor downwind who is paranoid about anything blowing down in the wind); I suspect we can use a rock-and-sand filled plastic pipe for the base (concrete fill would be beyond our budget) and do some eyeball engineering for the rest
I'm anxious to get at least ONE bat house occupied this year, as then I would be eligible to apply for one of the small research grants and be able to try out some of the other designs I can think of -- not that there aren't already some innovative bat habitat designers !
now to find some less expensive stain -- the prices at two of the local places gave me sticker-shock, especially since they had only gallon cans, and my materials list says I need only a quart ...
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"Candy"
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Dave Miller
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Posted: Thu Feb 12th, 2004 06:23 pm |
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Sorry I meant to say "masonry" chimney. Putting a house on a metal chimney would be a bad idea.
Old strandboard might be OK. Pallet slats would work nicely for the interior crevices. If any surface is smooth it will need to be roughened.
I just used plain exterior black paint, not stain. I have repainted once in 6 years. If you have a friend with a dark-colored house you could ask if they have any paint/stain you could use - they probably do.
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Dave Miller
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Posted: Thu Feb 12th, 2004 06:45 pm |
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Looking through my notes, I found the procedure I used for raising the old power pole that my bat house is on. This would work for any heavy pole. Do be careful though, if the pole falls on you, it might kill you. Power poles are much heavier than you would think. Also I should mention that the pole is about 21' long - I cut some off from the original pole.
Here is the procedure: http://www.pacifier.com/~davem1/bats/PoleProcedure.txt
I tried to just paste it here but the ASCII "drawings" only work in a monospaced font.
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Posted: Thu Feb 12th, 2004 06:50 pm |
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dark colored house -- hmmm, that's an idea :idea: --- not any in this neighborhood, ours is probably the darkest (finished with redwood-colored SunFrog treatment, basically "drying" linseed oil with suspended color in it -- NOT what you'd want for a bat house), next door neighbors just repainted their place "sea foam green" almost like our old '61 Chevy ...
however, I just remembered that the HazoHouse at the Lacey transfer station (we don't call them dumps anymore) does have a "donate or trade" room, with paint and stain and household chemicals and suchlike; think they're open only on weekends this time of year ... might be something there we can use, at the same time we get rid of some old chemicals we found thrown over the bank north of our property :sad:
someone else suggested using a can of black spray paint, but I noticed that BCI specified WATER-based paint or stain, and I doubt that spray paint fits that criterion -- oh yeah, I need it liquid anyway because we put the bat house together first, unpainted, and I seem to recall that the interior is supposed to be stained black -- am sure it is watertight so it should be stain-tight too :smile: just pour it in and slosh ...
we had the wrong vehicle with us yesterday, so today I'll go salvage that strandboard pallet and anything else that looks usable; put it up on the deck in the sun where it can get dried out, though weather forecasters say we are in for more spring downpours ...
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"Candy"
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Dave Miller
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Posted: Thu Feb 12th, 2004 07:13 pm |
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Portland has a very nice paint recycling center, perhaps you have one too: http://www.metro-region.org/article.cfm?articleID=521
Supposedly the paint is very high quality because some of the liquid has evaporated, making a higher percentage of pigment.
You might be lucky enough to find a dark color at the transfer station. I would stay away from spray cans.
I am pretty sure you are supposed to put NO FINISH on the interior surfaces, especially stain. The interior is completely protected from the weather, assuming the exterior does not leak. So it does not need to be, and should not be, coated with paint or stain. The concern is outgassing of the finish on hot days, and making the surface too smooth for the bats to hang from.
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Joe Spencer
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Posted: Fri Feb 13th, 2004 02:13 pm |
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By the way, does anyone know if bats and wasps "battle" over a roost? It seems that they like similar roost spots. If they do battle, who generally wins
Dave I believe who arrives in the greatest numbers first (foothold) wins? but it seems often there is no clear winner. Bats also seem to coexist with wasps utilizing different chambers in a nursery house for example. I believe it was BCI that found that when other smaller bat houses were mounted nearby the WASPS would use them (supply demand) and would reduce or eliminate wasp numbers at the primary utilized bat houses. Since Wasps are discouraged from 3/4 inch chambers it might be useful to setup some bat houses which have larger chambers which wasps readily accept such as 1" - 1.5 inch and which bats reject. Regading darkening the interior of a bat house: It may have some merit but like Dave has said the heat would surely bring out the petroleum products in the stain if used but as newbie mentioned above water-based products are available. Has anyone tried Black Food Coloring concentrated with water in a spray bottle?  : Great stuff in this thread makes me anxious for spring and bat house building... 
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