Spotted bat (Euderma maculatum)
provided by EOL authors
The spotted bat is a species of vesper bat (Family Vespertilonidae). Joel Asaph Allen described the bat in 1891. The bat is 10-12 cm long with a 35-3 cm wingspan, 4 cm long ears and weighs 15-20 g. It has mainly jet black fur with two large white spots on its shoulders and one white spot on its rump. The fur on its underbelly is snow white. The wings are pink in color and the ears have a pinkish tone. Total length, 126 mm; tail, 51 mm; hind foot, 12 mm; ear, 47 mm; forearm 48.51 mm. The Spotted bat is so named for its three white spots located over each shoulder and on the rump. The surrounding dorsal fur is black while the ventral fur is light with dark underfur. The face is black and the ears and wings are pale. It lives in undisturbed roosts on cliffs in arid regions along the Grand Canyon in Arizona, as well as open and dense deciduous and coniferous forests (especially Ponderosa Pine forests) , hay fields, deserts, marshes, riparian areas and dry shrub-steppe grasslands in rugged landscapes in Nevada, Montana, Nevada, Wyoming, Arizona, California, Colorado, Utah, and British Columbia, Canada and into central Mexico from the Pacific coast to the Rocky Mountains inland. It may occur at 3000m above sea level or below sea level in the deserts of California (Pierson and Rainey 1998; Poche 1981; Watkins 1977). Their habitat is associated with a water source such as a spring, creek, river or lake. This species seems to be roost faithful; they return to the same diurnal roost every night in the summer. In the Autumn their behaviour becomes less predictable. Typically at a site usually only one is caught per night; individuals are well dispersed, separated by distances of 750-1000m of each other. Some bats migrate from colder to warmer regions in winter, such as Ponderosa pine high elevation habitats in June and July to lower elevations in August. Bats enter torpor in cold weather; the body temperature falls to that of their surroundings and the heart rate slows. They roost in the small cracks found in vertical cliffs and stony outcrops and in open canyons. The bat rolls of its ears around its head when it rests. When it becomes active, the ears inflate with blood and unroll. The bat is solitary and territorial. Its echolocation sound (9-12kHz) is low enough to be heard by humans. It uses vocalizations to communicate with neighbours. An apparent territorial dispute involved vocalization and direct contact. Only in one study had the bat foraging in groups. In most studies the bats forage up to 10 km from their diurnal roost and seem to forage constantly. They fly in elliptical patterns from their roosting sites. A lactating female flew 35.8 km straight from her diurnal roost around 23:00 h to a foraging site, roosted there for part of the night (01.00-03.30 h) and flew back to the cliff day roost. Other bats at the location followed that nightly pattern. This behavior could be a compromise between suitable diurnal roosting sites and foraging sites. Foraging behaviour does not seem affected by the amount of moonlight at night. The bat feeds mainly on grasshoppers and moths; it tears off a moth's wings and only eats the addomen. The low frequency calls limit the bat to catching large flying insects, apparently specializing on large moths that cannot detect echolocation calls of such low frequencies. Insects seem to be caught in the air at a rate of about one every 45 seconds and most recorded foraging behaviour occurs 11 pm-3 am. Natural predators include owls, raccoons and skunks. The mating season is in autumn and females usually produce one young in June or July. The newborn pup weighs 20% of the adult weight and does not have the distinctive color pattern and fully developed ears of the adults. It may fly by July, but lactating females have been caught as late as August. The bat may live up to 20 years in the wild. The biggest threat to the bat is human-caused changes to the environment. Bats may acccumulate pesticides through their diet. Using DDT and other insecticides in the 1960s led to a severe decline in the spotted bat population, but the bat is more common than formerly believed and is listed 'LeastConcern' by the IUCN Red List. It is thought to be one of the rarest bats in North America and a species of special concern. In the 100 years from the time of its discovery to 1990, only 14 individuals were collected in California. Since then the number of locations where spotted bats have been found in that state has tripled. While the distribution is very patchy over this range, the species may be locally common. It occupies a very large range, but is seldom abundant. Conserving diurnal roosts (rocky cliffs with snug cracks for roosting), seems the best way to protect this bat. Large open foraging sights, where their echolocation is most effective, and large moths for prey are important conserving the bat. Compiled using Animal Diversity Web (http://animaldiversity.ummz.umich.edu/accounts/Euderma_maculatum/), Arizona-Sonora Desert Museum (https://www.desertmuseum.org/kids/bats/Spotted%20bat.php) and Wikipedia (en.wikipedia.org/wiki/Spotted_bat) The author for the Animal Diversity Web website was Sofia Hussain and the editor was James Patton, both from the University of California, Berkeley.