Bat House Forum

[IowaNate]

Now I have had a few bat houses of my design hung on trees, and they were occupied...but I never considered the effect on the tree since they were usually of large diameter (18"+).
I am hanging a bat house at our cottage on the Mississippi River on a smaller white ash tree (about 10" diameter) and have concerns about keeping the tree alive. Are there certain screws which are less harmfull than others to trees? This tree is perfect...being only 30 feet from the river, no branches untill 20 feet, and the tree doesn't branch out much at all above 20 feet so there is minimal shading.
I plan to hang the house facing Southeast at 15 feet...and given the huge success rate of tree mounted houses on this island, I feel I have a great chance of attracting a nursery colony of little browns.
The bats on Abel Island will roost in almost any 3/4" crevice that is at least 8 feet from the ground from my observations over the last 2 years.
I am still not sure what style of bat house I will hang here, but I want it to have the least damaging effect on the tree itself. Any suggestions?

[Joe Spencer]

Do Screws and Nails harm trees?: http://www.chron.com/disp/story.mpl/gardening/huber/5212931.html

I believe screws do less harm than nails since nails split and allow more space for disease to enter. Not sure about this though. If you must use fasteners might I suggest stainless steel screws and then place silicone caulking on the screw between the screw and the back of the bat house. That way it may form a flexible sealant to help keep out anything while the tree grows and potentially heals. Despite what the link above reports, we know many trees have survived trauma with millions of bullets from hunters and wars being found in trees after they're cut. While building my home the state contractors working on my road accidentally scraped a one foot piece of Bark off a large tree between my yard and the street. It has taken 6 years and the tree is now 90% dead which stresses the importance of bark on a tree. Amazing how a trees' bark can survive a forest floor fire but not a large gouge or bark removal.

[Dave Miller]

I have begun using bungee cord when mounting bird houses in trees. You might give that a try. It would probably take several strands to support a bat house.

[Joe Spencer]

I like that idea Dave! It can expand while the tree grows. I keep forgetting that like WD40, bungees have 1001 uses too! We just bought a cheap baseball pitch-back for my young sons and it is horribly made and won't last long. 2x4's used as a frame with bungees tacked to the inside with electric wire staples coupled with some S-hooks might make a great sturdy unit. I thought about it last night and should have connected it with Nate's request. Glad you did!

[Erik]

Hi Dave,
could you post a picture of a bird or bat house mounted with bunjee rope? I am interested in that idea!
Erik

[Dave Miller]

I had to run off before completing my thought there re: bungee cord.

I have found that the quality of bungee cord varies quite a bit. The old adage "you get what you pay for" certainly applies. You can buy it by the foot at hardware or sporting goods stores. I have never had bungee cord break, but I have had the cheap ones lose elasticity, which can be bad news for the tree and/or the house.

I have been using it with bird houses for about 6 years. I would guess that I'll need to replace them at about 10 years.

I just drill two holes at the top of the house and two at the bottom, that are the size of the bungee cord. Put the cord through one of the holes at the top, and tie a knot to keep it from pulling out of the hole. If the house is not too heavy, you can lift the house from this one cord.

When you are up at the top of the ladder (or in the tree), pull the house up and wrap the cord around the tree, preferably over a north-shooting branch or knot. Pull the cord through the other hole at the top of the house, tight enough so that the house weight is just supported by the cord (but not too tight, it needs some elasticity). Tie a knot to keep it from pulling through the hole, and cut off the extra.

Do the same at the bottom of the house. Actually it is a better if it is a bit up from the bottom - so that if the top cord does eventually break, the house will still be held in place by the bottom cord. If the cord is at the very bottom the house will just do a "face plant" into the tree if the top cord ever breaks.

As I said, if the house is really heavy, you might want to use two or more strands at the top.

It would be nice to get a color that matches the tree, but don't sweat it too much since the cord will be partly/mostly covered by lichen, etc. after a year.

[Dave Miller]

Hi Dave,
could you post a picture of a bird or bat house mounted with bunjee rope? I am interested in that idea!
Erik

Will do!

[Dave Miller]

Hi Dave,
could you post a picture of a bird or bat house mounted with bunjee rope? I am interested in that idea!
Erik

Will do!

Here you go...



Notice that the bungee cord is red, but a lot of it is now covered with green lichen, etc. This cord has been on this tree for about five years.


Lazy man method:


Note that the cord goes over a branch on the other side of the tree:

[IowaNate]

This weekend marks the hanging of the bat house on the island. I am using my "Economy" three chamber bat house which should be capable of housing up to 300 little browns (the predominant species on the island).
My observations show that about a hundred of bats fly within 10 feet of this tree in the evening, and the morning "swarm" is the same. So occupancy could happen VERY quickly.
I decided to use stainless screws to mount the house to the tree, and I should only have to put 4 screws in to minimize any chance of damage to the tree. And I hope I can get it mounted by tommorrow evening to maximize the number of evenings I can observe it before I have to leave on Monday.
I will be taking photos of the finished mounting and the landscape around it.

This is a very exciting moment for me since I have been trying to get a bat house at this location for two years!

[IowaNate]

Here are two photos showing the bat house. The first is of the front in the morning sun (about 9 am). And the second is from the back in the mid-afternoon (about 5 pm). I had numerous little browns fly within 5 feet of it during the first 2 nights it was hung, but no occupancy that soon. I am headed up to check on the house this weekend and hopefully there will be some residents!

[Joe Spencer]

Great bat house pictures Nate! Looking forward to occupancy feedback....

[IowaNate]

No bats as of yet, but I did witness something interesting. While I was watching the bats during their evening flight, I saw one bat briefly land on the landing pad of the bat house and then take off again. I counted over 3 dozen bats flying within 5 feet of the bat house in 15 minutes time, so hopefully patience will pay off soon!

[Joe Spencer]

Yes that does sound promising Nate.