Bats in Wisconsin in May

Yes, May is a good month to see bats in Wisconsin. It is the 6th busiest month of the year, with 59 of the 546 sightings logged across the year (10.8%), based on verified iNaturalist records.

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By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.

Eastern Red Bat photographed in WisconsinBig Brown Bat photographed in WisconsinBig Brown Bat photographed in Wisconsin
Photos by iNaturalist observers, used under Creative Commons.

Good month for bats in Wisconsin

10.8%

of yearly sightings

59

records in May

#6

busiest month of 12

546

verified records a year

April 7.7%, May 10.8%, June 11.2%. Busiest month is August at 21.2%.

Best months: August, July, SeptemberPeak season right now

546 verified observations of bats in Wisconsin, recorded across 12 months of the year on iNaturalist.

When bats are recorded in Wisconsin

Peak month

August

116 records (21.2% of the year)

Quietest month

February

9 records

MonthObservationsShare
January101.8%
February91.6%
March234.2%
April427.7%
May5910.8%
June6111.2%
Julypeak7213.2%
Augustpeak11621.2%
Septemberpeak6211.4%
October6011%
November193.5%
December132.4%

Bats you are most likely to see

SpeciesVerified observations
Big Brown Bat212
Silver-haired Bat50
Eastern Red Bat49
Little Brown Bat48
Northern Hoary Bat15
Tri-coloured Bat10
Northern Myotis1

In Wisconsin, May carries 10.8% of the year's bats sightings, about 2.5 points above an even month-to-month split. That makes it the 6th busiest of the twelve months, out of 12 months with recorded activity.

Activity is rising from April (7.7%) into May, and it heads toward June (11.2%) after. The busiest month is August (21.2%), so if timing is flexible, that window is the safer bet.

The bats most often recorded in Wisconsin are Big Brown Bat, Silver-haired Bat and Eastern Red Bat. Those counts are annual totals rather than a May split, so treat them as which species you are likely to encounter, while the month figures above show how many sightings fall in May itself.

Which bats you are most likely to see

  • Big Brown Bat212 records
  • Silver-haired Bat50 records
  • Eastern Red Bat49 records
  • Little Brown Bat48 records
  • Northern Hoary Bat15 records
  • Tri-coloured Bat10 records
Plan your tripApostle Islands National Lakeshore

Plan your bat trip in Wisconsin

Start with live tours near Apostle Islands National Lakeshore, then compare a nearby stay and a broader wildlife backup before you lock in the trip.

Gear to see them

Frequently asked questions

Can you see bats in Wisconsin in May?+

Yes. May accounts for 59 of the 546 verified bats sightings logged in Wisconsin across the year, which is 10.8% of the annual total.

Is May a good time to see bats in Wisconsin?+

May is the 6th busiest month. It is workable, though August and July is the stronger window for a reliable sighting.

What month is best for bats in Wisconsin?+

August is the single busiest month, with the broader peak running through August, July and September, based on 546 verified observations.

Which bats are you most likely to see in Wisconsin?+

The most-recorded species in Wisconsin are Big Brown Bat, Silver-haired Bat and Eastern Red Bat, based on all-time iNaturalist counts.