Greater Mouse-Eared Bat (Myotis myotis) Dispersal and

Conservation

K.C. Chaney

Why Should We Care?

• Conservation success story, listed as “Vulnerable” in 1994

• Listed as “Least Concern” in 2008

• Conservation efforts

were successful, but

might need to be

reevaluated

Distribution and Numbers

• Bats now number in hundreds of thousands, with 80,000 bats in 290 colonies in Bavaria alone (up from just 70 colonies in 1985)

• Black line is distribution for Myotis myotis

Lifestyle

• Average lifespan of 10-13 years

• Feed on insects

• Prefer to hunt in forests with little ground cover, but will also use residential lawns and agricultural fields

Mating

• Females and young live in nursery colonies, ranging from as few as ten bats to almost 1,000

• Males live in solitary roosts that the females visit, traveling upwards of 12km, in late autumn for mating

• Multiple matings, males mate with around 7 partners, females can mate with up to 19

• Females exhibit delayed fertilization, holding onto sperm until late winter/early spring

• Roost sites range from caves to attics

Nursery Colonies in Bavaria

Effects of Nursery Protection

• Total population below 4000 in 1993 • Peaked in 1997 over 8000 • At the end of data collection, total population numbered more than 6000.

Change in Habitat

• Bats in nursery colonies huddle together for warmth

• Temperature is the biggest factor in offspring fitness

• Loss of forests has prompted movement towards smaller colonies in insulated areas such as attics

Dispersal Rates

Dispersal model based on colony having 100 females (squares), 450 females (circles), and 1000 females (triangles)

• Females usually stay in the colony where they were born • Males disperse up to 200km

Male Roosts and Breeding Sites

• Males will share roosts, but not at the same time

• Most roosts are empty for a majority of the time, even during breeding season

Why Does This Matter?

• While large nursery colonies are easy to identify, breeding sites (which are often empty) and small nurseries are much harder to locate and protect

• Breeding sites and small nursery colonies in buildings are threatened by attic and roof repairs

• Simply protecting larger nursery colonies might not be enough to ensure protection of species in the future

Summary

• Gene flow in Myotis myotis is mostly due to male dispersal

• Protecting large nursery colonies alone does not guarantee the protection of the species, but has been effective so far

• If you ever happen to live in Europe, roofing and attic repairs should be done outside of the mating season (August-October) to ensure bats don’t lose access to breeding and smaller nursery sites

References

• Schneider, M., M. Hammer. 2006. “Monitoring the greater mouse-eared bat Myotis myotis on a landscape scale.” Monitoring Nature Conservation in Cultural Habitats 4; 231-246

• Arlettaz, R., M. Ruedi, C. Ibanez, J. Palmeirim, J. Hausser. 1997. “A new perspective on the zoogeography of the sibling mouse-eared bat species Myotis myotis and Myotis blythii: morphological, genetical, and ecological evidence.” Journal of Zoology 242; 45-62.

• Zahn, A., B. Dipple. 1997. “Male roosting habits and mating behavior of Myotis myotis.” Journal of Zoology 243; 659-674.

• Petri, B., S. Paabo, A. Von Haeseler, D. Tautz. 1997. “Paternity assessment and and population subdivision in a natural population of the larger mouse-eared bat Myotic myotis.” Molecular Ecology 6; 235-242.

• Castella, V., Ruedi, M. and Excoffier, L. (2001), “Contrasted patterns of mitochondrial and nuclear structure among nursery colonies of the bat Myotis myotis.” Journal of Evolutionary Biology, 14: 708–720

• Arlettaz, R., 1996. Feeding behavior and foraging strategies of free-living mouse-eared bats, Myotis myotis and Myotis blythii. Animal Behaviour 51; 1-11.

• Reproductive success, colony size, and roost temperature in attic dwelling bat Myotis myotis. Journal of Zoology 247; 275-280

Questions?