Myotis dasycneme

 

Myotis dasycneme, commonly known as the pond bat, belongs to the family Verspertilionidae in the genus Myotis.  There are 94 species in the genus Myotis, typically designated as little brown bats, and around 40 of these share the same subgenus with the pond bat, Leuconoe (Altringham 45).  The pond bat has a wingspan of anywhere between 20 and 32 centimeters and weighs about 14 to 20 grams (Limpens 10).  The coloration of the pond bat is as follows:  the upper part is usually a shade of brown and the underside is paler (Nowak 188).  Myotis bats are distinguished from other Vespertiliondae by their longer muzzle.  They also tend to have softer, shorter fur (Rosevear 302).    The whole Myotis genus is distinguished by having six pairs of cheekteeth in the upper and lower jaw (Taylor 95).  The pond bat is known for living mostly in Europe.  Its distribution is from the Yenisey River in eastern Russian to the areas around Netherlands, Denmark, and Sweden.  Its range from north to south is from about 48 degrees north to 60 degrees north.  There have been records of the Myotis dasycneme in Manchuria but it is not thought that they regularly travel that far east (Limpens 10). 

            The population estimate for the pond bat for a long time was greatly underestimated.  In 1988 it was thought that there was only a world population of only 7,000, but this has since been disproved.  Experts have since concentrated on the population on their individual countries and, for example, the newest estimate for Hungry alone is around 10,000 bats.  The Netherlands also carried out a new survey, which concluded that the pond bat population there was also around 10,000.  It is now believed that the world population of pond bats ranges anywhere from 100 to 200 thousand bats (Limpens 13), refuting past claims that the ³Myotis dasycneme is rare and probably endangered² (Pauza 65). 

            Pond bats are thought to travel up to 15 kilometers to forage for food.  They fly fairly fast, at a speed up to 35 kilometers per hour, and tend to stay about 30 centimeters above large bodies of water.  They use two main techniques while foraging for food.  They will trawl, which is to grab an insect off the top of the water with their feet, or they will hunt down their prey a few meters above the water or onto the land with a technique called aerial hawking.  Pond bats will also pick up insects off the surface of the water using the membrane of their wing.  Pond bats usually start their foraging trip shortly after sunset, about an hour, and will fly for up to an hour to their foraging area.  They will return to their roosts about an hour before sunrise.  During the summer and fall a large percentage of the pond bats will stay out all night because they do not have to go back to the roosts to feed their young.  The food of the pond bat is relatively unknown beyond insects.  The diet has been studied by testing the feacal pellets and the breakup was mostly Chironomidae with about 30 percent consisting of Coleoptera, chirnomid pupae, caddis flies, and lacewing (Limpens 14).

            The reproductive pattern of the Myotis dasycneme is that they mate during the fall, the females store sperm in the uterus during hibernation in the winter, ovulation and fertilization takes place in early spring, and then birth occurs in the late spring or early summer (Nowak 189).  The female pond bats become sexually mature around August of their second year and begin mating from that year onward.  Although a case of twins has recently been documented with the Myotis dasycneme, they normally produce only one young a year.  The female pond bats will start living in the maternity roosts after the end of March and will stay until their young has been born and starts flying, which is usually about 5 weeks after birth (Limpens 15).  The female pond bats almost exclusively live in the nursery roosts from April to September and then migrate in the beginning of autumn (Leeuwangh 518).  Male pond bats become sexually active in the beginning of autumn and will stay in the roosts with the female and young until they both leave the roost.  These nursery colonies are usually only made up of sexually active males, females, and young, and it is rare to find male pond bat that is not yet sexually active in these roosts (Limpens 15).

            Anywhere from 67 to 70 percent of pond bats survive birth and this usually depends on the time of year.  More survive in the summer than in the winter.  If a bat survives birth its life tends to span about 13 years, but the life expectancy for these pond bats is barely 3 years.  The oldest recorded pond bat was around 19 years old (Limpens 15).

            The habitat requirements for pond bats ³should, on a larger scale, provide a complex habitat elements allowing successful roosting, foraging, and dispersal/migration between roosts and hunting habitats, and between summer haunts and habitation sites² (Limpens 16).  The pond bat uses many different roosts throughout the course of a year such as a maternity roost, which female bats use while caring for their young, male roosts, which the males use during the summer period but not during mating season, night roosts, which are used for resting, and eating or digesting food while the bats forage, transitional roosts, which house the females, young males, and juveniles during the summer, mating roosts, which males use to mate with a number of females during the season, migration roosts, which are temporary roosts used by the pond bats during migration, and hibernacula, which the bats use during the winter time to hibernate.  Often times roosts are used multiple times and for several different purposes (Limpens 16).  The pond bat roosts occur in many different areas depending on the use.  Good examples of suitable bats roosts are caves, hollow trees, attics, churches, and hollowed walls (Child 1).

The echolocation calls by Myotis dasycneme are in most cases frequency modulated and comparable to that of other trawling bats.  During the time when the bat is approaching its prey its calls are similar to those when it is searching for prey, but often shorter.  The bat uses shorter more rapid FM calls while approaching its prey as opposed to when looking for it (Britton 513).  ³Vespertilionid bats foraging in dense or cluttered environments generally emit short, broadband pulses, whereas vespertilionids in open spaces use long duration, narrowband pulses² (Verboom 63).  The calls were also shorter when the bats were flying in a bunch.  The pond bat also lengthens its calls depending on how far away the object the call is directed at (Milner 1).  Compared to similar smaller bats, the calls of the pond bat tends to be around 10 kilohertz less because of the size difference (Britton 513). 

The flight speed of the pond bat also varies depending on the activity.  During attempted captures of prey its flight speed will decrease as well as the wing beat frequency.  They practice a short glide right before they capture their prey in order to increase their feet placement accuracy and increase the lift immediately after the capture.  The pond bat also flies faster in territories it knows better.  During migration, the further from its roost the bat gets, the slower it goes.  However, these speeds are still significantly faster than when the bat is foraging.  The wing beat frequency also slows down during longer flights.  It is negatively correlated with the speed, so as the speed goes up the wing beat frequency goes down (Britton 518).

  The pond bat is included in several agreements, such as Appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats, classifying it as a species that needs to be protected.  A group of specialists has met to decide exactly what measures need to be taken to preserve the existence of the pond bat.  It was decided that the main focus should be site protection, especially of the maternity and hibernation colonies, which tend to be underground.  This has greatly helped the known roosts, but there are still many more that are not known.  One step taken to protect the underground roosts of bats in abandoned mines was the implementation of grates over the entrances.  This would allow the pond bats to fly through and not allow for human interference as well as deter other species of bats, such as horseshoe bats from roosting there in the summer.  Steps like these are becoming more and more common but still occur mainly on a local level, and the preservation of the pond bat species will not be truly effective until actions are taken on a national or even worldwide level (Limpens 23).

 

 

 

 

 

 

Works Cited

 

Altringham, John D.  Bats Biology and Behavior. 3rd ed. Oxford: Oxford UP, 1999. 45.

Britton, A. Flight Performance, Echolocation, and Foraging Behavior in Pond Bats,

Myotis Dasycneme (Chirotera : Vespertilionidae).  Journal of Zoology.  Vol. 241. 

1997.  503-522.

Child, Jenny.  Bats in my Belfry.  Lancet.  Vol. 343.  Issue 8888.  1994.  5-7.

Leeuwangh, P. Bats and Woodpreservatives.  Pesticide Residue in the Dutch Pond Bat

(Myotis Dasycneme) and its Implications.  Mammalia.  Vol. 49.  1985.  517-523.

Limpens, Herman J.  Action Plan for the Conservation of the Pond Bat in Europe. 

Strasbourg: Council of Europe Publishing, 2000.

Nowak, Ronald M.  Walkerıs Bats of the World. Baltimore: Johns Hopkins UP, 1994. 

189.

Pauza, D. H.  Bats of Lithuania: Distribution, Status, and Protection.  Mammal Review. 

Vol 28.  Issue 2.  1998.  53-67.

Rosevear, D. R.  The Bats of West Africa. Margate: Eyre and Spottiswoode Limited

1965. 302.

Taylor, Peter John.  Bats of Southern Africa.  Scottsville, South Africa: University of

Natal P, 2000. 95.

Verboom, Ben.  Acoustic Perception of Landscape Elements by the Pond Bat (Myotis

Dasycneme).  Journal of Zoology.  Vol. 53.  1999.  59-66.

 

 

Matt Johnson

HONR278C

23 February 2004