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Photo © Wisconsin DNR
Eastern Red Bat (Lasiurus borealis) has brick-red to yellow-red fur that is tipped with white, giving the bat a frosted appearance. Eastern red bats are insectivorous and prefer to feed on moths. During the summer months, red bats are found in various forested habitats including deciduous woodlands with elms and maples. The bats may be found foraging near trails, fields and wetlands. In the fall, the eastern red bat migrates south to warmer climates where they may enter short bouts of torpor in leaf litter or hanging in deciduous trees. The eastern red bat mates during fall migration and females give birth in early June to one to four pups. This species is not actively tracked in the Natural Heritage Inventory Database, but it could be tracked in the future if there is further evidence of its decline.
The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Eastern Red Bat (Lasiurus borealis). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.
Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.
| Summary Information | |
|---|---|
| State Status | none |
| Federal Status in Wisconsin | none |
| State Rank | S3 |
| Global Rank | G3G4 |
| Tracked by NHI | W |
| WWAP | m-SIN |
Identification: Eastern red bats have distinctive red or brick colored fur with makes them easily distinguishable from other bats in Wisconsin. They will often have some hairs tipped with white, giving the bat a frosted appearance. Females will often have more frosting than males. The ears are short, round and sometimes covered in hair. The tail membrane is also thickly furred, unlike most bats in Wisconsin.
Habitat: Eastern red bats migrate south in September and October to overwinter in a diverse forest structure, usually hibernating in the foliage of deciduous and coniferous forest on the south side of the tree. Some individuals may hibernate in leaf litter when temperatures drop below 10 degrees Celsius. In summer, from April to September, both male and female red bats roost alone in mature riparian forests close to edge habitat, open water, or fields. They prefer to roost in 1-6 meters off the ground in tall, large-diameter deciduous trees such as elms and maples on south facing branches. Red bats forage along forest-field edges, forest gaps, riparian areas, and near artificial light sources.
State Distribution: Eastern red bats are found throughout the state from April to October. More research is needed to accurately determine state-wide range for this bat species.
Global Distribution: The eastern red bat is highly migratory and is found in the eastern part of North America from the Rocky Mountains- east in summer and may migrate to southern California and Arizona to overwinter.
Diet: Eastern Red bats eat primarily moths and beetles.
Life and Natural History: When hibernating in winter, eastern red bats will often use trees or leaf litter and curl their tail around themselves in an effort to conserve heat, and sometimes emerge from torpor in the afternoon before sunset to feed. Red bats mate in the fall during migration and perhaps while overwintering. Sperm is stored in the uterus of the female over the winter until spring migration to summer habitat. Gestation lasts 80-90 days and two to three pups are born in June. Red bats have four mammary glands, and may give birth to up to five pups. After about five weeks, the pups are able to fly by themselves and begin exploring on their own. Eastern red bats have low roost fidelity and sometimes even switch roosts nightly. After emerging from hibernation and wintering grounds, reproductive female red bats will often migrate longer distance than males which can lead to highly skewed sex-ratios in certain parts of the county in summer months.
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Photo © Wisconsin DNR.