What Is the Summer Bat Maternity Season?

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Bat maternity season depends on the specific bat species in question, and on the type of climate that species lives in. Depending on the region, in the US, bat summer maternity season can start as early as mid-April, and end as late as mid-August. Of course, maternity season will start earlier in warmer states, and a little bit later in cooler states.

• The evening bat (Nycticeius humeralis) maternity season will begin on the 20th of April and end on the 15th of July;
• The Mexican free-tailed bat (Tadarida brasiliensis) maternity season will last from the 20th of May to the 10th of August;
• The maternity season for both the little brown bat (Myotis lucifugus) and the big brown bat (Eptesicus fuscus) will start on the 1st of June and end on the 15th of August.

Bat maternity season also means it's time for bat maternity colonies, when either smaller or larger groups of pregnant bats roost together in dark, warm spaces they deem safe. And while caves are perfect for such activities, our relentless urban expansion often leaves bats with no other option than to initiate maternity colonies in abandoned buildings, or even in inhabited households.

Learn more: What is White Nose Syndrome?

Dealing with a bat maternity colony on your property can be noisy and smelly, and large amounts of bat guano may lead to more serious issues, including threats to your health, or even to the structure of the building they roost in. Nevertheless, the typical North American bat colony is made of approximately 40 female bats who each give birth to one pup. This means you won't be dealing with huge quantities of bat waste.

Being a natural pest control expert, the bat does wonders in helping our ecosystem to remain balanced in terms of insect population. Any change in bat population could be severely detrimental to our natural biodiversity, fact that will bring further irreparable damages to man-handled crops, farming, and to other animal species. This is why it is illegal to exclude bat maternity colonies. Special circumstances may grant you an official permit to evacuate bats during maternity season, but this is not a common situation.

Find out more: What kind of noises and sounds do bats make when they live in your house?

Excluding a bat maternity colony is also not a smart idea because of a whole bunch of other reasons. For example, by removing bats with one-way exclusion devices, you will only catch mother bats, as only the adults leave the colony to hunt. This means the pups will be left to starve, die, and rot – not a nice scenario. Additionally, bats are dedicated mothers, and if they find a way to return to your property, they will try to get back to their babies by any means necessary. Desperate bats swooshing through windows and doors – again, not a nice scenario. When the baby bats are ready to fly and hunt for themselves, they'll leave on their own, the colony will disassemble, and exclusion will no longer be necessary. Once the colony scatters, make sure there are no returning unwanted guests, safely disinfect the area inhabited by the bats, and seal shut all the access points that the bats could've used to get in and out. It's not easy, I know, but that's why we have wildlife removal professionals.

If you're dealing with a bat situation on your property, remember to consult the bat maternity season schedule – if the date and species fit, you already have your answer: you'll just have to wait for maternity season to end in order to take care of the situation.

For more information, you may want to click on one of these guides that I wrote:
How much does bat removal cost? - get the lowdown on prices.
How to get rid of bats - my main bat removal info guide.
Example bat removal photographs - get do-it-yourself ideas.
Bat job blog - learn from great examples of bat jobs I've done.