Wednesday, October 29, 2008

Bats In The Garden.

Mormoopidae: Pteronotus parnellii (Mustached bat), Brazil. Photo by L. H. Emmons. Smithsonian Encyclopedia Bat Facts

Garden Rant is a daily read around here. If the days offering is of particular interest then I will be back and forth often, following the conversation. Sadly my own favorites do not always get enough play. So today I thought I would hijack the subject.

While I do not garden to attract bats they are welcome. Gardening with wildlife in mind will encourage any local bat population. Bats need food (mostly insects), water (that pond or bird bath) and a safe undisturbed home for resting and reproducing.

Although some species of bats are endangered by loss of roosting space or open accessible water, bats in general are not rare even in urban areas. Cities are full of crevices, hollows and perches where bats may creep in or hang from, hidden away for the daylight hours. You might find a single bat or quite a few if there is room. Bat colonies tend to grow as signs showing inhabitants have been successful over time, draw more bats to investigate (hence the advise to place guano beneath your manmade bat house).
Some bats live in hollow old trees while others make do with loose bark peeling away from dead branches or trees that tend to shed old bark. An endangered Indiana bat (sometimes found locally in Chicago area) camouflaged so well it was comfortable just hanging onto the bark quite exposed. Other bat species do not overwinter in cold climates but migrate futher south where food is plentiful during winter. During their warm weather stay in the north the canopy of a tall densely branched tree can be home enough.
The exterior of a building will often have a multitude of hiding places for a young inquisitive bat. Behind an upper story shutter,loose siding, space just a 1/2 inch wide along a roof edge all and more will provide a warm place for a tired bat to get cozy for at least a day. Hopefully the bat will not be able to enter the dwelling proper to find space in the attic. That is not good for the homeowner or the bats. Window screen placed over all entrances to the attic will exclude bats and keep hibernating species from entering.

Any garden will have plenty of insects . A light left on at dusk will show just how many insects there are and provide a buffet area for bat residents. A Rose of Sharon in my garden draws large night moths right outside one bedroom window. At night I have been known to watch for a dark shape quickly passing. It would be very cool to see a bat catch dinner. Maybe we should look into Bat Detectors .

All bats need an accessible water source but especially lactating mothers. Bats drink by flying low over water and scooping up mouthfuls of water as they pass. Leaving an open flyway without dense planting will help as even bats need space to lift high again. An interesting article in National Wildlife
discussed drowning bats in water tanks for domestic animals and how to solve the problem.

Bats are part of a healthy ecosystem and we can learn to live with them, even in a garden.

For your reading pleasure...

drinking water
When bats or birds fall into tanks, they splash along the edges searching for a way out. If the water level is even a few inches below the rim, the animals are likely to find escape impossible. How many bats are killed in stock tanks yearly is unknown. However, the loss is so high, Tuttle says, that biologists have recommended skimming stock tanks for bat skulls to determine which species occur in an area.
To reduce this threat BCI, in partnership with the Natural Resources Conservation Service, last year launched a program for putting escape ramps into troughs and storage tanks. A variety of ramps can be made out of expanded metal, which looks like heavy steel mesh. To be effective, a ramp must have side skirts that touch the inner wall of the tank. Ramps that merely rise from the water like a bridge, with no skirts, do not help, as bats and other animals simply pass under them. The side skirts provide animals with an escape route that they meet as they clamber along the tank edge. They can climb up the skirt and out of the water.
For details on making wildlife escape ramps for water tanks, visit Batcon.

Directionality of drinking passes by bats at water holes: is there cooperation?

These are the bats found in Illinois,
FE means federally endangered,
SE means state endangered.
You should check with a local resource to see which bats could be found in your area.
All bats are protected.

This list is from the Illinois Natural History Survey web site, mammals page: UIUC

Order Chiroptera: BatsFamily Vespertilionidae: Vespertilionid bats
Myotis lucifugus (Le Conte, 1831) - Little brown bat
Myotis sodalis Miller & G.M. Allen, 1928 - Indiana bat FE
Myotis austroriparius (Rhoads, 1897) - Southeastern myotis SE
Myotis grisescens A.H. Howell, 1909 - Gray bat FE
Myotis septentrionalis (Troussart, 1897) - northern long-eared bat
Lasionycteris noctivagans (Le Conte, 1831) - Silver-haired bat
Pipistrellus subflavus (F. Cuvier, 1832) - Eastern pipistrelle
Eptesicus fuscus (Beauvois, 1796) - Big brown bat
Lasiurus borealis (Müller, 1776) - Red bat
Lasiurus cinereus (Beauvois, 1796) - Hoary bat
Nycticeius humeralis (Rafinesque, 1818) - Evening bat
Plecotus rafinesquii Lesson, 1827 - Rafinesque's big-eared

NPR bat story beating the odds.

Bat House Success Tips


Listing of Issues and Articles at Bat Conservation International website concerning bat house research...

Successful Bat Houses Shed Light On Bat Needs. The Bat House Researcher. Vol 1, No. 1:1-2.
Five houses in Maryland, Wisconsin, and New York that received sun for 8 to 12 or more hours daily were all occupied. Three of these were either painted dark or were covered with tar paper. The two that were left a natural wood color received 12 or more hours of sun. Twenty-two bat houses in other northern locations received less than four hours of daily sun, and none of them were occupied, clearly confirming the vital role of solar heating. Even in the South, only one of 11 occupied houses received less than four hours of daily sun, while nine that received little or no sun were unoccupied.

Reminder to Owners of Unsuccessful Bat Houses

IF AFTER AT LEAST ONE active season, your bat house remains unoccupied, try moving it to a new location where it receives more or less sun. Reports thus far indicate that most successful bat houses are occupied within the first year, and that most failure results from too little exposure to sun. A house that fails at first, but is occupied after a move, may provide especially enlightening information on what local bats need.

If your houses are mounted on poles, try rotating them from a north/south exposure to sun to east/west. Since houses seem to be too cool more often than too warm, this may help. If your houses are insulated and empty, try removing the insulation to permit greater heat gain. You also can try painting houses a different color, most often darker.

Attaching nursery houses back-to-back on poles may reduce extremes of temperature fluctuations. Such houses in the hottest climates may benefit from tin roofs with enough overhang on the east and west sides to reduce solar heating during mid-day.
Ventilation slots, like those used by Lisa Williams, are also a good idea.


Blogger Cheryl said...

I love bats.....they use our loft space in the summer to breed......and have done for the last seven years. We live in a 400 year old house and in the UK bats are welcome to roost in loft spaces........I found it really interesting that you said that it was not a good idea...
The bat conservation project in the UK encourages it.......

Interesting post....enjoyed reading it.......

29/10/08 1:22 PM  
Anonymous susan harris said...

I too love bats and haven't given up on my quest to lure them to my bathouse.
Thanks for the extra info, GLoria.

30/10/08 6:53 AM  
Blogger Gloria said...

Cheryl, a link to your own Bat Conservation Trust might explain.
Disturbing bat roosts especially maternity roosts is illegal.
Building maintanance is often necessary in buildings. Excluding bats from residential buildings to stop a roost from forming may be better for everyone.

Susan,I added bat house success tips to the post because of you.

30/10/08 6:32 PM  
Blogger Defining Your Home said...


Your blog is a wealth of information! If you hadn't left a comment on my blog (Defining Your Home Garden), I don't know if I would have found you.

I'm going to link to your blog from mine.

We have no mosquitoes on my property and our friends and family can't believe it. We garden to attract wildlife and use organic products. Bats, hummingbirds, dragonflies, birds, frogs--all assist with our mosquito control. I also grow lavender and I do believe in the natural repellant properties.


31/10/08 9:54 AM  
Blogger Gloria said...

Thank you Cameron. I found your blog a few days ago maybe at Garden Rant or else looking for information about carex.
We still get a few mosquitoes but having a wildlife garden has created a much better insect balance in the garden.

31/10/08 1:56 PM  

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