Geographic Range
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
Habitat
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.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- forest
Physical Description
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.
- Other Physical Features
- endothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- female larger
Reproduction
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.
- 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
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
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).
Behavior
Daubenton’s bats are nocturnal and leave their roosts about 30 to 60 minutes after sunset. They frequently change summer roosts, as often as every 2 to 3 days for females. Details regarding the social behaviour of the Daubenton’s bat are poorly documented.
Males regularly enter daily torpor but do so less frequently during spermatogenesis.
Females enter daily torpor in the late summer after juveniles are weaned but avoid
it during pregnancy and lactation. While in torpor, Daubenton's bats maintain a heart
rate of 108 to 120 beats/minute, and skin temperature drops to 8.9 to 10.2 °C. After
waking, they have a heart rate of 450 to 750 beats/minute and skin temperature is
raised to 36.5 to 37.6 °C.
Daubenton’s bats typically hibernate from September to March, though many other bats begin hibernation in October and November. The number of individuals inhabiting a single hibernaculum can vary but typically does not exceeding 140. Females leave hibernacula later than males; this late departure may help females conserve energy until more resources are available in the late spring. Dispersal distance from winter to summer roosts typically does not exceed 100 km. In Britain, dispersal distance is typically less than 19 km while in continental Europe it ranges from 0.5 to 88 km.
During hibernation, the time spent in torpor depends on the temperature of the hibernaculum; duration of torpor decreases as temperature increases. On average, bats wake every 22 days when hibernaculum temperature is 3 to 5 °C, 14 to 18 days when 5 to 7 °C, and 14 to 16 days when 7 to 9 °C. Maximum torpor duration is 79 days.
Daubenton’s bats maintain body water and accumulate urine during hibernation. Muscle water content remains constant at 66.1 % while in hibernation, slightly lower than water content in August, which averages 69.3 %.
Daubenton’s bats lose approximately 20 to 21 % of their body mass in 100 days of hibernation.
- Key Behaviors
- arboreal
- troglophilic
- flies
- nocturnal
- motile
- migratory
- hibernation
- daily torpor
- social
- colonial
Home Range
The average distance between roosting sites and preferred foraging ground of Daubenton’s
bats is approximately 236 m. The maximum distance found between a roost and forage
site was 800 m. Although territoriality has been observed when strong winds limit
foraging area, Daubenton’s bats usually forage in groups in non-restricted feeding
sites.
Communication and Perception
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
Food Habits
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.
- Primary Diet
- carnivore
- Animal Foods
- fish
- insects
Predation
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.
Ecosystem Roles
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 (
Argas 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.
- bat fly Nycteribia kolenatii
- bat fly Nycteribia schmidlii
- bat fly Nycteribia vexata
- bat fly Penicillidia monoceros
- bat fly Basilia nana
- mites Spinturnix andegavinus
- ticks Argas vespertilionis
- flukes Plagiorchis vespertilionis
- fleas Ischnopsyllus simplex
- fleas Myodopsylla trisellis
Economic Importance for Humans: Positive
Daubenton’s bats play an important role in controlling populations of the many pest
species they feed on
Economic Importance for Humans: Negative
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
Conservation Status
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.
Other Comments
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.
Additional Links
Contributors
Timothy Gingera (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Gail McCormick (editor), Animal Diversity Web Staff.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- sperm-storing
-
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
- delayed fertilization
-
a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- female parental care
-
parental care is carried out by females
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- hibernation
-
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
- social
-
associates with others of its species; forms social groups.
- colonial
-
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- ultrasound
-
uses sound above the range of human hearing for either navigation or communication or both
- echolocation
-
The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.
- chemical
-
uses smells or other chemicals to communicate
- carnivore
-
an animal that mainly eats meat
- piscivore
-
an animal that mainly eats fish
- insectivore
-
An animal that eats mainly insects or spiders.
References
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