conserve ireland

 

Daubenton’s Bat

 

Common Name Scientific Name Irish Name
Daubenton’s Bat Myotis daubentoni Ialtog uisce
Order Family Group
Chiroptera Vespertilionidae Mammal
Daubentons Bat Daubentons Bat Daubentons Bat
footprints    

                              
           

                              

Legal Status

Wildlife Act 1976 / 2000
Directive 92/43 Annex IV
Bern Convention Appendix II
Bonn Eurobats Convention Appendix II


 

Key Identification Features

Daubenton’s bats are a small to medium sized species which is also known as a pond bat as it mainly hunts over water. The fur is short and brown on the upper body with a pale greyish tint on the underbelly. Adults weigh 14 grams at their heaviest in autumn and slim down to 9 grams in the summer after their long hibernation period. The average head and body length of an adult measures 5cm with a long 4.5cm tail. The face is hairy with a pinkish brown colour with very short rounded ears which are the smallest for a bat species of this genus. The feet are furry and unusually large for an animal of its body size. Wing design is fairly narrow and broad with wing membranes being dark grey to brown in colour and span up to 2.7cm. In flight the species can reach 25 kph with slow fluttering wing beats allowing it to fly in a zig zag pattern while hunting over water. The echolocation range for this bat falls between 30 - 80 kHz but they will not emit communication calls while in flight. When communicating within the roost they emit a chirrup sound. An abrupt colour change occurs with juveniles being greyer and darker than adults and also possessing a dark patch under the chin which disappears once the bat reaches one year of age.

 

Habitat

The preferred habitat type of the daubenton’s bat is on low lying open or wooded countryside which is located near a freshwater body. This species will generally avoid urban areas. An individual may travel up to 10km from the roost site to hunt each night especially if they are following a linear watercourse. The roost size for this bat species are usually small containing on average ten individuals. Roost sites are sometimes shared with other bat species particularly brown long – eared bats, natterer’s bats and pipistrelles. Summer roosts can be located in tree hollows, attics and lofts with maternity colonies forming in summer time containing breeding females, their offspring and young non-breeding females. Males will sometimes be found in the summer roosts but tend to gather together in separate clusters. Winter roosts need to be high in humidity and between 3 – 6 degrees Celsius so such sites are usually established underground in mines, caves and cellars where bats will squeeze into crevices or hang freely from the wall in tight clusters.

 

Food and Feeding Habits

The daubenton’s bat emerges from the roost to hunt later than other bat species usually thirty minutes to one hour after sunset to avoid daytime predatory birds. The daubenton’s bat however may be active by day as large numbers of its preferred prey gather in large swarms before dusk. This bat species is specialized in hunting over freshwater bodies, flying low over the surface and sending out ultrasonic pulses parallel to the water to locate insects. Once located the prey is grabbed with the bat’s large feet or scooped up using the tail to be eaten while in flight. The favoured prey items for the daubenton’s bat in Ireland are small winged insects such as midges, caddis flies, moths, gnats and may flies. The daubenton’s bat species needs to regularly drink water more so than any other Irish bat species.

 

Reproduction and Life Cycle

The mating season for the daubenton’s bat starts in October and may run until February while the bats are within their winter roosts. After mating the female bat will delay fertilization of her eggs until the spring. Once gestation begins it usually lasts for up to seven weeks but this will depend on the weather conditions. Young bats are born from June to July and weigh on average 2.5 grams at birth. Their eyes will have opened by their fourth day when they will also be completely covered in fur. The young are capable of solo flight by their third week but will continue to be weaned until they are six weeks old. Parental care is given by the mother only. Most daubenton’s bats do not become sexually mature until their second year which is quite late for an Irish bat species. Some females, despite becoming sexually mature will not breed every year. The hibernation period for this bat is also quite long running from September until April with females entering their hibernation phase before the males. The average lifespan for a daubenton’s bat in Ireland is around 7 years but some individuals have been recorded as having a 40 year lifespan which is extremely long for such a small mammal.

 

Current Distribution

The oldest fossils that gave rise to modern bats date from 50 million years ago. Past climatic changes such as the last Ice Age seriously affected the number and range of bats but they can now be found in most habitats throughout the world except for land areas near the poles. Bats are believed to have evolved from small insect hunting mammals, which occupied the tree canopy of forested areas of the Eurasian continent. The present day bat family tree now contains 950 different species divided into 17 families. The Daubenton’s bat species belongs to the vespertilionidae family in the Chiroptera order which includes leisler’s bats, whiskered bats and brown long-eared bat species in Ireland. Daubenton’s bats are now widespread throughout the European continent and range eastward through to Russia although they are absent from northern Scandinavia, Bulgaria, Romania and Greece. They were present in Britain 6,000 years ago and were most likely to be found in Ireland at this time although they were not scientifically identified here until 1838. They can now be found throughout Ireland in most counties.

 

Conservation Issues

Daubenton’s bats are sensitive to water quality deterioration as a rise in pollution levels will have an adverse effect on the number of aquatic insects on which they are totally reliant as they are a specialized freshwater insect hunter. Winter roosts can easily be destroyed due to building restoration with the sealing of cracks and crevices entombing hibernating colonies. The habit of some mature females to not breed every year and the fact that most young bats do not become sexually mature until their second season means any losses are harder to recover from. The increase in the creation of artificial water bodies in Ireland like canals and recreational lakes has increased the daubenton’s bats choice of habitats in recent years although the water quality of such water bodies must be protected. The daubenton’s bat is listed as a species of international importance and is protected under national, European and international legal agreements.