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Daubenton’s bats, Myotis daubentonii, once included three subspecies: M. d. daubentonii, M. d. laniger, and M. d. petax. The latter two subspecies have since been given specific rank.
Female Daubenton’s bats emit social calls while inside nursery summer roosts. The frequency of social calls while foraging is low but increases dramatically when males chase other males from a foraging area. It is possible that females recognize their young through olfactory and auditory cues.
Daubenton’s bats produce frequency modulated (FM) calls that sweep from 70 to 95 kHz to 25 to 30 kHz and last 3 to 4 milliseconds during the search phase. The bandwidth of the first harmonic during search flight is approximately 70 kHz. Pulse intervals are highly variable. The approach and terminal phases are characterized by an increasing reduction of both sound duration and pulse interval. The terminal phase is separated by a longer interval and involves two buzz phases. The second buzz has a lower frequency than the first, dropping from 25 to 30 kHz to 22 to 18 kHz. At the end of the second buzz phase, the bandwidth of the first harmonic may drop as low as 10 kHz. When emerging from the roost, calls last 2.2 to 3.8 milliseconds and are spaced 56 to 103 milliseconds.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; ultrasound ; echolocation ; chemical
Myotis daubentonii is an abundant species found through the majority of the Palearctic region. Within recent decades, population numbers have increased, possibly due to favorable climate change and increased food abundance. It is designated as a “species of interest” by the European Union Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora. It is considered a species of "least concern" by the IUCN.
US Federal List: no special status
CITES: no special status
Daubenton’s bat serve as a reservoir species for the EBLV-2 virus, which causes rabies in humans. However, this virus is maintained at low levels in the population and transmission to humans is low. The principle means of transmission of this virus is by bite from an infected bat.
Negative Impacts: injures humans (carries human disease); household pest
Daubenton’s bats play an important role in controlling populations of the many pest species they feed on
Daubenton’s bats are effective insect predators and likely have an effect on aquatic insect populations. One individual consumes 3.6 to 4.9 g of insects in one night, and pregnant females and males undergoing spermatogenesis consume approximately 8.0 g of insect material per night.
Daubenton’s bats host a variety of parasites, particularly bat flies. Common bat flies that parasitize Daubenton’s bats are Nycteribia kolenatii, N. schmidlii, N. vexata, Penicillidia monoceros, and Basilia nana. Mites (Spinturnix andegavinus), ticks (Carios vespertilionis), flukes (Plagiorchis vespertilionis), and fleas also parasitize Daubenton's bats. The flea species Ischnopsyllus simplex (in the west) and Myodopsylla trisellis (in the Far East) are commonly found on Daubenton's bats, though neither are host specific.
Commensal/Parasitic Species:
Daubenton’s bats are opportunistic insect predators. They feed primarily on aquatic insects of the order Diptera. Approximately 96 % of their diet consists of male midges that swarm above the water’s surface as females emerge from the water. Other aquatic insects, such as crane flies, black flies, biting midges, fungus gnats, and dagger flies make up 2 % of their diet.
Both in captivity and in the wild, Daubenton’s bats occasionally use their large feet to lift small jumping fish that break the water’s surface. Little data is available regarding the importance of piscivory to the diet of Daubenton’s bats.
Daubenton’s bats catch their prey from still water surfaces using slow hawking and gaffing techniques. Flight path while searching for prey is greatly affected by size of the foraging site. In a more confined site (i.e., small drainage canals), Daubenton’s bats fly alone in straight paths. At larger sites such as lakes and ponds, they forage alongside other individuals. Searching typically takes place within 30 cm of the water’s surface. When a prey insect is detected, Daubenton’s bats approach either directly or with sharp turns. Flight speed is reduced slightly during low catches closer to the water surface and is drastically reduced during high catches farther from the water’s surface. Prey is captured by the feet or the interfemoral membrane and is eaten when seized.
Pregnant females and males undergoing spermatogenesis have a higher energy demand than post-lactating females and normal condition males. Assuming a 92 % catch rate, pregnant females have an insect intake of 8.0 g while post-lactation females have an intake of 4.9 g. Similarly, males undergoing spermatogenesis have an insect intake of 8.0 g while normal males have an intake of 3.6 g.
Animal Foods: fish; insects
Primary Diet: carnivore (Piscivore , Insectivore )
Daubenton’s bats, Myotis daubentonii, inhabit the majority of the Paleartic region, occurring from Ireland, Portugal and Norway through continental Europe and northern Asia to continental Japan, Kamchatka, China and Korea. In Europe, they range from 63 °N in Scandinavia to 40 °N in Greece. Within Japan, they is only found on the island of Hokkaido. Daubenton’s bats can also be found in south-western and central China.
Biogeographic Regions: palearctic (Native )
Daubenton's bats prefer to live in areas with extensive still water lakes, ponds, and streams for foraging, and deciduous and mixed forests for roosting. During the summer, Daubenton's bats seem to prefer cavities of deciduous trees for roosting sites, but they may also be found under bridges, in buildings, bird boxes, bat boxes, rock crevices and the nests of sand martins. They prefer oak trees over other tree species and natural cavities over cavities created by woodpeckers. Daubenton’s bats may prefer natural crevices as they are formed by rot, which is indicative of humid conditions. Crevices found near the edge of a wood are also preferred, likely because of increased light exposure during the day, which aids in thermoregulation.
Nursery roosts of Daubenton’s bats are usually found in lower altitudes, most likely because these areas have higher ambient temperatures and lower precipitation. These nursery colonies are predominantly composed of females and can be occupied by more than 100 individuals.
In the winter, hibernacula are typically found in underground sites such as caves, mines, bunkers, and cellars. Temperatures of the hibernaculum can range from 0 to 10 ° C but are usually 2 to 6 °C or 3 to 8 °C. A minimum humidity of 70 % is needed for overwinter survival, and most hibernation roosts occur in sites with over 85 % humidity. It is not uncommon for Daubenton’s bats to form clusters with other bat species with similar thermal preferences (i.e., Myotis natlereri).
In the summer, the upper altitudinal limit of Myotis daubentonii is 400 to 700 m, and in the winter, 300 to 1100 m.
Range elevation: summer 700; winter 1100 (high) m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest
Other Habitat Features: urban ; suburban ; riparian ; caves
The mean life expectancy of Daubenton’s bats in the wild is 4.5 years, and mean longevity is 5.0 years. Although the predicted potential lifespan of a Daubenton’s bat is approximately 20 years, the oldest individual recorded in the wild was 28 years old.
In the Netherlands, survivorship of juveniles within the first half of their life was 50% and was 80% for adults. There was no difference in survival between age and sex groups or between hibernacula (Bogdanowicz, 1994).
Range lifespan
Status: wild: 28 (high) years.
Average lifespan
Status: wild: 4.5 years.
Daubenton’s bats are medium-sized bats with a body mass between 5 and 15 g. Females are on average slightly larger than the males. Daubenton’s bats have a head and body length of 40 to 60 mm and a wingspan of 240 to 275 mm. The forearm measures 33 to 42 mm and the tail length is between 27 and 48 mm.
Newborn bats typically have a mass of 1.6 to 2.4 g. Their mean head and body length is 32.8 mm, and they have a mean tail and forearm length of 15.7 and 14.9 mm respectively.
The short, dense fur of Daubenton’s bats is characterized as brown-gray to a slightly red dark bronze on the dorsum and silver-gray to white on the belly. The wings are reddish or dark brown but never black. The face is blunt and pinkish with bare, hairless patches around the eyes. The ears are short and rounded and clearly separated. The pinnae have 4 to 5 transverse folds and are 10.5 to 14.2 mm in length. The tragus has a height half that of the pinna and a width one-fifth the pinna length.
Newborn Daubenton’s bats have short, gray-brown hair on the dorsal side and a pinkish ventral side. The ears and wing membranes are gray-brown.
Some diagnostic characters of Daubenton’s bats include a large foot that is half the length of the tibia, a long and slender calcar that is about two-thirds the margin of the uropotagium, a plagiopatagium that inserts in the middle of the metatarsus, and a relatively broad penis that is not bulbous.
Daubenton’s bats have a smooth and relatively flat and broad skull. The postorbital processes, temporal crest, and sagittal crest are weak and not very prominent. The lambdoidal crest is quite laterally strong but is obscure medially. The auditory bullae are also quite large and cover two-thirds of the cochleae. The dental formula is: I2/3, C1/1, P3/3, M3/3 for a total of 38 teeth. The upper molars have well developed protoconules on the anterior edge.
Range mass: 5 to 15 g.
Range length: 40 to 60 mm.
Range wingspan: 240 to 275 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Although many mammalian and avian species have been recorded preying on Daubenton’s bats, none seem to be habitual predators. In most instances, predators seem to take advantage of high bat densities. Domestic cats, beech martens, dormice, wood mice, and shrews are the most commonly reported species that prey on Daubenton’s bats. Common avian predators include barn, tawny, and long-eared owls, however Daubenton’s bats make up less than 1.0 % of all vertebrates eaten by these owls. Other predators include buzzards, large frogs, and large fish.
Known Predators:
Daubenton’s bats are typically promiscuous (males and females mate with multiple partners). Mating is unstructured, with little to no male courtship display. Males, however, actively search roosts for females and create special mating roosts during the late summer. Most copulations occur in these special mating rosts.
Mating System: polygynandrous (promiscuous)
Male and female Daubenton’s bats reach sexual maturity in their first year. Males are typically able to reproduce during and after August of their first year, though some may not reach full maturity until their second summer. Mating typically occurs as soon as the males reach the hibernaculum and continues from August to April. However, most copulation occurs between October and November. Most mating occurs ventro-dorsally and is typically accompanied by distinct vocalizations and body positions. Copulation lasts approximately 15 to 30 min.
Female Daubenton’s bats exhibit delayed ovulation. Fertilization occurs in early spring, and pregnancy lasts from 53 to 55 days. Pups are born from June to July. Although females have a high food requirement during pregnancy, pregnant females often have a reduced foraging rate. Lactating females have lower energy requirements than pregnant individuals but tend to have a further reduced foraging range. While the actual lactation period is not well recorded, it is usually thought to occur between June and July.
During birth, female Daubenton’s bats reverse their typical “head-down” position so that the young are born into the uropatagium of the mother. Litter size typically consists of a single pup, rarely two. Young are born blind but have well developed sensory hairs. The eyes open within 8 to 10 days. The deciduous teeth are almost completed erupted at birth, and permanent teeth erupt on the 8th day. Permanent tooth development and eruption is complete around the 31st day. Pups obtain their complete cover of hair on the 21st day, and hair development is complete between the 31st and 35th day. Young are able to fly by 3 weeks of age and attain full adult form within 9 to 10 weeks.
Breeding interval: Males and female Daubenton’s bats breed multiple times in a year.
Breeding season: Daubenton’s bats generally mate between October and March.
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 53 to 55 days.
Average age at sexual or reproductive maturity (female): 1 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; sperm-storing ; delayed fertilization
Mother Daubenton’s bats likely use olfactory and auditory cues to recognize their young in nursery roosts. Similar behavior is seen in little brown bats. It is possible that nursing females do not actively groom themselves or their young, as nursing females and juveniles have a significantly higher parasite load compared to non-nursing females and solitary males. Juveniles are weaned around August. Information regarding parental care in this species is poorly documented.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
