Eastern Red Bat

Eastern Red Bats are North America’s most abundant migratory tree bats. Their carrot-red color and frosty appearance make them distinct from other bats. 

Mostly solitary, they flock together when migrating into warmer areas during winter. They often roost in deciduous forests and suspend themselves by a single foot. Because of their cryptic coat and hanging posture, one could mistake them for hardwood leaves swaying on tree branches. 

Description

Length: Total – 93 to 117 mm (3.6 to 4.6 inches)  Body – 40 to 50 mm (1.5 to 1.9 inches); Hindfoot – 6 to 11 mm (0.2 to 0.4 inches); Forearm – 36 to 46 mm (1.4 to 1.8 inches); Ear – 8 to 13 mm (0.3 to 0.5 inches)

Weight: 7 to 14 gm

Body and Coloration: 

Eastern Red Bats are named after their carrot-red pelage. Males have a more reddish coat than females, while the latter appear more frosty, showing sexual dimorphism.

Each hair is divided into four colored regions. The base is dark gray in males, followed by yellow, carrot-red, and white bands. The yellow band is more extensive in females, and the red is replaced by maroon, displaying a dull chestnut coat. The white tips at the end of the strands make these bats look frosty. There are white patches of hair restricted to their wrists and shoulders. 

Their ears are short and rounded. The wings encased in a thin, membranous patagium are made of slender hand bones that extend during flight and help fold the wings while roosting.

Distribution

They range from southern Canada through Central America, extending further south into Chile and Argentina. 

Habitat

They prefer sparsely populated, forested areas far away from human intervention. Often residing on the edges of pastures and croplands, they usually build their roosting sites in large deciduous trees. However, they can also roost in coniferous vegetation when required.

Diet

Like most insectivorous bats, they catch moths, flies, beetles, spittlebugs, and plant-hoppers while flying.

Behavior

1. While foraging, they quickly pass through a population of potential prey, such as insects, and fix a target within a range of 5 to 10 meters. After spotting an insect, they chase it for a while before diving and grabbing it within inches from the ground.
2. During winters, they migrate to northern parts of their range around April and return in late October. They typically hibernate in hollow deciduous trees. Their body temperature is just above freezing during this time, as they cannot tolerate subfreezing temperatures for long periods.
3. They interact through echolocation, using both high and low-frequency calls. This form of communication enhances their foraging capacity and helps them locate their prey better.  

Lifespan

In the wild, these bats have an average lifespan of about 12 years. The lifespan of this species in captivity is still unknown. 

Reproduction and Life Cycle

Mating in Eastern Red Bats takes place in flight during late summer, right before they set out for migration. During winter, the sperm are stored in the uterus and oviducts, which delays fertilization.  Like all females of the genus Lasiurus, females of this species can give birth to a maximum of four young ones. They also possess four mammary glands for feeding them at once.

Like other temperate bats, they give birth to a single litter around early summer. The newborn bats learn to fly in about five weeks and are weaned around that time.

Predators 

The blue jays are the most common predator of these bats in eastern North America. Its other predators are snakes, opossums, and birds of prey like merlins, loggerhead shrikes, great horned owls, sharp-shinned hawks, and American kestrels.

Adaptations

1. They have long, narrow wings adapted for rapid flight, covering up to 40 miles per hour.
2. Their reddish coat color helps them camouflage with sycamore, oaks, elm, and box elder trees, perfectly resembling hanging leaves.
3. The membranous patagium in their wings acts as a blanket during cold months of hibernation.
4. They are more light tolerant than some other North American species, such as brown bats. Such an adaptive feature helps them capture insects from street lamps and light traps at night.

Conservation Status

According to the IUCN, this species belongs to the ‘Least Concern’ category. Because of their large population, wide range, and tolerance to habitat disturbances, these bats are thriving well in this age of diversity loss.

Though not alarming, a high mortality rate has been reported around wind turbines in some areas of the United States. Hence, wind turbine operational adjustments are needed for their protection. Since they hibernate in leaf litter, certain forestry activities involving controlled burning can result in their accidental death.