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Soprano Pipistrelle - Pipistrellus pygmaeus
Soprano Pipistrelle - Pipistrellus pygmaeus

[Image: Pipistrellus_pygmaeus01.jpg]

Scientific classification
Kingdom:  Animalia
Phylum:  Chordata
Class:  Mammalia
Order:  Chiroptera
Family:  Vespertilionidae
Genus:  Pipistrellus
Species:  Pipistrellus pygmaeus  (Leach, 1825)

The soprano pipistrelle (Pipistrellus pygmaeus) is a small bat that in taxonomy was only formally separated from the Common Pipistrelle (Pipistrellus pipistrellus) in 1999. It is possible that these two groups diverged from one another in the Mediterranean and that is why the Pipistrellus pygmaeus has the ability to thermal regulate at such high temperatures as 40 degrees C.
The two species were first distinguished on the basis of their different-frequency echolocation calls. The common pipistrelle uses a call of 45 kHz, while the soprano pipistrelle echolocates at 55 kHz. The two species are sometimes called the 45 kHz pipistrelle and the 55 kHz pipistrelle, or the bandit pipistrelle (common) and the brown pipistrelle (soprano). Since the two species were split, a number of other differences, in appearance, habitat and food, have also been discovered.

[Image: Pipistrellus_pygmaeus_range_map.png]
Global range of P. pygmaeus (green)

Habitat and distribution

The Soprano pipistrelle is known to roost throughout Europe in rooftops and houses. One study, done by Lourneco and Palmeirim, found that the reason behind a preference for rooftops was because of the available thermal differences throughout a roof. Although Soprano pipistrelle can thermal regulate up to 40 degrees C it prefers not to go above this temperature. Rooftops give the maternity colonies access to cooler spots on warmer days and warmer spots any other time. They achieved this observation by trying out different colored bat boxes and seeing how frequented they were. Although the black bat boxes could get too warm they were most frequented because of the love of warmer temperatures of this bat. In a study done by Nicholls and Racey, the habitat of the Pipistrellus pygmaeus was found to be small around 487 ha. It consisted mostly of agriculture land but also saw a significant increase in woodland edge and glasslands used as habitat. When it came to foraging habitat though, the Pipistrellus pygmaeuschose riparian woodland over all other habitats by a significant amount. Water followed in as second and these two habitats combined made up "77% of foraging time". (Nicholls and Racey)

Roosting and foraging behaviour
The Pipistrellus pygmaeus was found to enjoy alternative roosting sites, to the extent that some found in one colony would exclusively use alternative roosting sites. When these bats were excluded from the original colony during a study done by Stone, et al., the bats did not return to the original colony but in fact started a new colony on one of the most preferred alternative roosting sites. The majority of these roosting sites were in buildings like bungalows and manors which were deemed unsuitable alternative roosting sites. The idea behind this alternative roosting could in fact be because of the torpor used by the Pipistrellus pygmaeus and the desire of the bat to be around 40 degrees C at certain times of its life, like when in maternity colonies. The Soprano pipistrelle only uses a small portion of its home range in order to forage and it is generally close to its day roost. Possibly because of the preference for foraging in a riparian habitat, many times these bats are seen overlapping each other's foraging areas. During reproduction and lactation foraging is done in longer flights, with similar flying times, but less bouts than the Pipistrellus pipistrellus. This is possibly because of the increased size of the colony of the Pipistrellus pygmaeus and the decrease need for energy because of thermoregulation. (Davidson-Watts and Jones) During the maternity colony times for the Soprano pipistrelle, there is an increased amount of wetlands within 2 km. This was noted also by Davidson-Watts and Jones as more than likely not by chance but deliberate. The majority of bats in a colony used one roosting site throughout the time of April to October most likely due to the need to be close to wetland habitats to acquire their specialized diet.

Soprano pipistrelle will congregate in maternity colonies while they are pregnant and nursing their young. This causes a problem for the human population because these colonies can get quite large, in fact much larger than the Pipistrellus pipistrellus colonies, which tend to be less than 200 bats. This large size of a colony causes a nuisance for humans because of the smell. During early pregnancy, Pipistrellus pygmaeus emerges later from its roost than it does in late pregnancy or lactation. This could be due to the large size of the colonies in the Soprano pipistrelle. Early pregnancy occurs in May and late pregnancy occurs in June and July while lactation occurs in August. (Lourneco and Palmeirim).

Compass orientation of a migratory bat species depends on sunset direction

by Forschungsverbund Berlin e.V. (FVB)

[Image: compassorien.jpg]
Soprano pipistrelle bat (Pipistrellus pygmaeus) Credit: Christian Giese

Millions of mammals navigate over thousands of kilometres each year. How they navigate during migration remains remarkably understudied compared to birds or sea turtles, however. A team of scientists led by the Leibniz-IZW in Berlin has now combined a mirror experiment simulating a different direction of the setting sun and a new test procedure to measure orientation behaviour in bats to understand the role of the sun's position in the animal navigation. The results demonstrate for the first time that a migratory mammal species uses the sunset direction to calibrate their compass system. Furthermore the experiment, which is published in Current Biology, indicates that this capacity is not inherited, and first-time migrating young bats need to learn the importance of the solar disc at dusk for nightly orientation.
The experiment that scientists Oliver Lindecke and Christian Voigt from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) designed and conducted together with colleagues from Latvia and the United Kingdom was based on two steps: First, several Soprano pipistrelle bats (Pipistrellus pygmaeus) were randomly assigned into two groups. At nightfall during their migration period, one group could watch the natural sunset at the Latvian Baltic Sea shore. The other group, however, watched the sun going down via a large mirror that reversed the direction of the natural sunset exactly 180 degrees.
For the latter animals, the real sunset was blocked from vision by the taped sidewall of their holding cages. Later at night, animals of both groups were transported inland, away from the beach of the Baltic Sea, for the second step of the experiment: On a forest meadow, one bat after the other was released remotely from a specially designed circular release box that was equipped to record the direction the animal flew when it left. Prior studies showed that take-off orientations could be used as a proxy for departure flight orientation in these bats.
"The new orientation assay, the circular release box for bats, ruled out any visual influence at takeoff and allowed us to compare the directions taken by bats of both groups," explains Lindecke. "The results show two fundamental aspects in bat navigation: Firstly, the setting sun's direction plays a crucial role because there is a significant difference in the bats' orientation with the group that experienced the mirrored sunset departing in opposite direction compared to the control group. And secondly, only adult bats showed directional preferences," Lindecke says. "Subadults displayed random orientation in both groups, which suggests to us that young bats need to learn long-distance navigation during migration from older conspecifics," concludes Christian Voigt, senior author and head of the Department of Evolutionary Ecology at the Leibniz-IZW. How this learning process works and which social factors and practices contribute to it remain unknown and require further investigation.
Mammals remain remarkably understudied with regard to navigation during migration. One of the reasons is a lack of experimental assays that measure a correlate of migratory orientation such as those that exist in birds and sea turtles. The larger migratory mammals, for example wildebeest or whales, are challenging to handle for any experimental work. Bats could fill this void as they have emerged as an important study model in movement ecology. They combine high ecophysiological diversity with a variety of movement behaviours. Bat eyes evolved to sense a wide range of light and a broad spectrum of wavelengths. Presumably, insectivorous bats like fruit bats rely heavily on vision when orienting over long distances since echolocation and path integration are ineffective and error-prone at distances larger than a few dozen meters. The results of this study are the first empirical evidence for the specific cues and mechanisms a migratory mammal uses for navigation.
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