Bat House Forum

[Len Kerry]

with the financial support of the company I work for in Australia, I am intending to install some two-chamber Rocket boxes on poles on a strip of natural land adjacent to the company premises. Based on the sensus results I've read in the "Researcher" a grouping of three poles would be advantageous.

I've limited my questions to two because I'd really like to have your advice on these matters which don't appear to be documented in the "Researcher".

To maximize the chances of success,
1. would it be best to align the poles in a straight line or would it be best to place them in a circular arrangement?
2. what would be the best (or minimum) spacing between the three poles in the two possible arrangements suggested above?

Thank you for your help.

[Joe Spencer]

Len since far fewer bat housers have had trials with Rocket designs than traditional designs there is not nearly as much feedback on design and placement. I would suspect that the placement criteria and success would probably be similar to bat houses which are mounted back to back on poles. Does your strip of land have water nearby? I would try starting out with 10-15ft. between them and try placing them in a straight line first and experiment with moving if not occupied aft first season. They will meet with the most success when not near other obstacles and are out in the open. Here is info from the original rocket box design placement: which may or may not help you specifically:

Occupancy rates are nearly 90% in some areas. Best use came where bat boxes were placed on forested ridgetops, in open areas near ponds, and along riparian habitats......

[Mark Kiser]

Hi Len,

Thanks for writing. I know of two instances where rocket boxes have been successful when installed in clusters.

At one location (Daniel Boone National Forest, KY), multiple clusters of 5 rocket boxes each were installed such that 3 were exposed to full sun, the other two to partial shade. Several species of bats used both sunny and shaded boxes at different times of the year. Apparently during the hot summers, bats moved into the more shaded boxes.

At another location (northwestern Washington state) there are six or seven rocket boxes in a group, probably arranged randomly on in a ?loose circle.? The species attracted to these boxes make a regular habit of switching every 2-3 weeks, moving from box to box in the group. Four of the boxes are identical in every way, so this behavior may have something to do with parasite or predator avoidance, rather than microclimate. A new rocket box installed in the group last year has an upper, outer chamber, sealed off and filled with 12 pounds (5.4 kg) of dry sand. This appears to be the new favorite among those bats, probably because it helps buffer temperature fluctuations.

The exact configurations at either place I am not sure of, but it probably does not matter whether it was a triangle, circle, or straight line.

My guess is that with 3 boxes, you should try a grouping that offers some variation or choice with respect to temperature.

I would place one in full sun, one in mostly sun (6-8 hours), and another in partial sun (3-5 hours). This way, bats have a wide range of choices.

Alternatively, you could vary the exterior colors on the boxes, dark, medium, and light to provide some choices.

I would probably space them about 15 feet apart, but again, that will depend on the terrain and how much sun you want each box to receive.

Hope this helps. Please let me know if you have any other questions, and let us know what kind of luck you have. We?d be interested in hearing from you.

Thanks for your efforts to help bats.

Sincerely,

Mark


Mark Kiser
Coordinator,
Bat House Research Project
Bat Conservation International
PO Box 162603
Austin, TX 78716
mkiser@batcon.org
512-327-9721 ext. 45
512-327-9724 FAX
www.batcon.org/bhra

[Kent]

Greetings Len,

John and Dan who designed the rocket boxes are using some 8" x 8" posts for the main part of the bat house where the bats roost.

The 8" x 8" material will retain more heat.

If it is possible you may want to use the 8" x 8" for one of the bat houses.


The rocket box is a very good bat house , it is critical to cut the top of the post at a long 45 degree angle . Most of the bats will roost at the top.

Kent Borcherding

[Len Kerry]

Thanks Joe, Mark and Kent for the responses.

Joe,
We are within 3km of a significant wetland reserve where bat activity is quite high - I do most of my bat detecting there! Although this range is well outside the 1/4 mile criteria of BCI, Australian bat literature indicates that many species commute several km between the day-time roost and the evening foraging area. I have also sighted bats in the vicinity several times before dawn in the winter months and one was actually found dead within office area of our building a few years ago. I think there is a reasonable chance of success.

Mark,
The strip is all new growth as a result of company sponsored plantings over the last few years - no trees are tall enough to provide any shade for the height I'm aiming for so I'll have to resort to different colour boxes. I agree that 5m (~16 feet) or greater would be a good spacing between posts.

Kent,
Thanks for the advice about the 8" x 8" post. When you say "a long 45 deg. angle", I presume that you are still refering to a 45 degree cut at the top on opposite sides of the post as per the original design and not a single sided cut?


Additional Questions/comments

1. Are we talking about two chamber rocket boxes (I originally was) or are some of you talking about single chamber boxes - I think Kent is!

2. I was thinking that the two chamber rocket box would offer more temp variation with the outer-chamber section facing east heating more quickly to provide early morning heating for just-returned bats and the inner chamber providing a lower temp refuge as the day heats up. What are your thoughts on the best choice, single or dual chamber rockets?

3. The outer sand cavity idea sounds interesting but wouldn't it slow down the early morning heating of the east-facing section?

4. The 8" x 8" post also sounds interesting - it would provide more thermal inertia but would still allow the outside wall of the cavity to heat-up quickly in the early morning.

5. Although I originally thought I'd use a galvanized pole in the design to avoid poisoning bats with treated wooden posts, I've been considering using treated wooden posts (which tend to be on the short side) but extending their length and providing the first inner roosting surface with a collar made from untreated pine boards of about 1.5m length - the lower 0.5m overlapping the top of the treated post and the outer-face of the upper 1m length forming the inner roosting surface of the inner chamber of the rocket box. If this is done, the 1m long cavity inside this collar could be filled with dry sand to provide thermal inertia for the inner chamber (I've adapted the sand idea mentioned by Mark and it may achieve a similar thermal effect to the 8" x 8" post idea mentioned by Kent). The 0.5m section overlapping the treated post would form the landing pad and the treated post could also be painted to provide further protection!

Any comments on this concept?

Thanks everyone,
Len

[Joe Spencer]

Sounds like a great plan Len and ya i would go with the multi/dual chambered rocket over a single. Yes the original single design did have the top of interior post angled at 45degrees I believe. Sure sounds like your site really is advantageous with the water and the fact that you had a bat in the building. When u say bat detecting do you mean visibly or do you have an electronic detector? You might also consider incorporating into one of the rockets' design a interior cavity above post in which sand or stones/rocks can be placed (SEE PHOTO BELOW my older megarocket design) for heat retention and stability. Then see which house the bats favor! Have you also noticed any bats feeding around your building? Commercial areas with high "White illuminated" lites "ORANGE hued lights don't attract many insects" attract numerous insects/moths for bats as well. Looking forward to your feedback on your progress mate! Also Below are plans for a two chambered rocket with color diagram:

http://www.dnr.state.md.us/wildlife/battwocham.html

[Len Kerry]

Thanks for the additional roost concept diagram Joe.

I design and build my own electronic bat detectors that I use to locate bat foraging sites so that I can spend time observing them. I love to watch their aerodynamic manouvres. The local wetland area (now a registered world conservation area) is a great location for bat foraging activity!

I haven't noticed any foraging activity in the vicinity of the building. There may not be much as its basically located in a cleared farmland/drained-wetland area that is slowly turning into a small-industry area. Hence the replanting activity undertaken by the company. However, with re-plantings and bat-boxes in position, I think it will be a good day-time roosting site for bats that are prepared to commute the 3km to the wetlands at night.

Although I have made a point of looking, I've never observed any local bats foraging around any type of street or building lighting.

UPDATE - I've just received word from the Enviro' group that quotations have been obtained for the supervised construction of the three rocket boxes I've requested. They're happy for the outlay so now I'm in the process of writing up a justification document that will be presented to senior management for financial approval.

It's very interesting to see the faces of people, who know nothing about bats, light-up when you give them a few interesting facts about bats and their specific roosting requirements. Their immediate amazement and facination has motivated them to move quickly on this project - I only approached them a week ago!

Regards,
Len

[Kent]

Len,

Your sand concept idea sounds feasible, but you may want to wait until bats began using some of the bat houses.

The angle at the top of the post and angle cuts into the post are critical to establishing bat colonies in the rocket boxes. It would be somewhat difficult to make the angle cuts in the design you were proposing to use. Once the bats began using the rocket boxes I would sure try the design with the sand in it.

The long 45 degree angle I was referring to is cut on each side of the post top.

Have you ever looked at Marvin Maberry's pivot post for mounting bat houses. Marvin's website is www.maberrybat.com. I am sure you or a friend could make a similir one for mounting the bat houses. I am not trying to take a sale away from Marvin ,but shipping to Australia could be pricey.

I think Marvin's pivot system is one of the best for bat houses.

If you use a 8" x 8' post for a rocket box, you could cut it 4 ft. long.
The box would be 3 ft. long. Drill a 2 " hole in the bottom of the 8" x 8" post deep enough for a 2" pipe to mount the rocket box on.

For rocket boxes I like to place another pipe inside the 2" pipe ,usually a 1" pipe. I think it makes the mounting pipes much more substanial from swaying and possibly bending in high winds. With the pipe in a pipe probably could use 1 1/2" pipe with a 3/4" pipe in it, should be as strong and probably more sturdy than 2 " pipe.

Definitely look at the pivot post at Marvin Maberry's web site. Marvin is also a helpful fine person if you have questions.


enjoy the bats,

Kent Borcherding