Soprano Pipistrelle Bat

Soprano pipistrelle, Pipistrellus pygmaeus

Morphological Description Life History Distribution Habitat Roost Sites and Roosting Patterns Emergence and Flight Pattern Foraging Behaviour Echolocation Calls Status and Protection
Morphological Description Dorsal fur is dark to chestnut brown. Ventral fur is paler. Ears are short and triangular with a rounded tip. The tragus is up to four times as long as it is broad. The wing membranes are opaque. The calcar is up to 1/3 of the length of the tail membrane and a post-calcarial lobe is present. The penis is slightly bulbous. Average weight (as given by Greenaway & Hutson, 1990) 4-8 g. The diagram below gives important average body measurements for soprano pipistrelles (Greenaway & Hutson, 1990).
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Life History Mate from the spring through to autumn, but mainly in September and November. Females may undergo torpor during pregnancy or lactation depending on feeding conditions. A single offspring is born at the end of June or the beginning of July. Rarely twins are born. Maximum age recorded in Europe is 12 years (Schober & Grimmberger, 1989). Back to top
Distribution

The British and World distributions are shown by the white areas of the maps above (as given by Richardson, 2000 and Corbet & Harris, 1991 respectively).
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Habitat
Back to top	The soprano pipistrelle prefers riparian habitats whereas the common pipistrelle uses a wide range of habitats (Vaughan et al., 1997). Glendell and Vaughan (2002) found that soprano pipistrelles often chose habitats with semi-natural woodland or tree lines. Tends to avoid open habitat such as farmland, moorland and grassland. The photograph on the left shows a typical habitat of soprano pipistrelles.
Roost Sites and Patterns
Summer roosts: in cracks and crevices in new and old buildings, behind panelling, shutters and eaves. Also found in bat boxes and trees. Winter roosts: trees, buildings. Exposed groups in crevices in walls and stonework. Rarely underground. Relatively insensitive to cold. Soprano pipistrelle roosts in houses are often unwanted. Lourenco and Palmeirim (2004) investigated the possibility of providing Mediterranean populations of soprano pipistrelles with bat boxes of suitable temperatures as an alternative. Bats were found to prefer the warmest regions in roosts, unless they were 40°C or greater. Black boxes were found to be at the correct temperature more often than white or grey boxes. However, bats left black boxes if ambient temperatures were particularly high. Females are found in nursery roosts of 25-50 individuals from April which they may share with Nathusius' pipistrelle. Barlow and Jones (1999) found that soprano pipistrelle nursery roosts were significantly larger than common pipistrelle nursery roosts. Males occupy territories year-round and defend them during the mating season when special social calls are emitted and the bats smell strongly of musk. Mixed sex winter roosts are inhabited from mid-November to early March. Back to top
Emergence and Flight Pattern
Emerge around 20 minutes after sunset, earlier on warmer nights. May emerge in daylight. Flight is erratic and agile. Flies usually 5-10m above ground level (Russ, 1999). Back to top
Foraging Behaviour
Often follows the same flight path every night. Foraging period changes with weather and reproductive state. Pregnant females forage once a night for a long period. Once the young are born females make two shorter foraging trips. The diet of soprano pipistrelles mainly consists of Diptera, particularly Chironomidae (Vaughan, 1997). Diurnal Diptera are also eaten. Aquatic insects are an important part of the soprano pipistrelle's diet and so they often forage near fresh water habitats. Aerial hawking is probably the predominant foraging strategy used, although some prey may be gleaned. Prey is caught and consumed during flight.

Marked in blue on the diagram above is a typical foraging path of soprano pipistrelles (based on Russ, 1999). Back to top
Echolocation Calls
	The echolocation call of soprano pipistrelles has both a frequency modulated and a continuous frequency component.
	To listen to the call of the soprano pipistrelle click here Size of sound file: 16.6 KB
	For details of how the echolocation calls were recorded click here.
	Average values for a soprano pipistrelle echolocation call, as given by Vaughan et al. (1997), are listed below: Interpulse interval: 81.0 ms Call duration: 5.7 ms Minimum frequency: 54.1 kHz Maximum frequency: 64.7 kHz The power spectrum on the left shows that the maximum power of the call is at a frequency of approximately 55.5 kHz. Kalko (1995) found four stages to the foraging behaviour of pipistrelles: search flight, approach flight, capture and retrieval of prey. Changes in the echolocation call were correlated with these changes in flight behaviour. There is a shallow-modulated component in the echolocation call during search phase which may enable better detection of prey. This shallow-modulated component is not found in the echolocation call during the approach phase. During the approach phase a steep frequency-modulated call is used to assess the distance to the prey item. In this phase the pulse interval and duration decrease as the target is approached. During the terminal phase steep frequency-modulated calls are used to locate the prey item precisely. Again, the pulse interval and duration decrease as the target is approached. The information contained in the call per unit time is increased through the use of a high call repetition rate. By altering the duration of the echolocation call, pipistrelles are able to avoid overlap between emitted signals and returning echos. Using a call with a duration of 6-10 ms, Kalko (1995) suggests that pipistrelles should be able to detect prey at a minimum distance of 1.12-1.70 m. Kalko & Schnitzler (1993) studied search flight echolocation of Pipistrellus species. During the search phase echolocation type corresponded to habitat type. Where obstacles were greater than 5m away from the bat the call was less than 15 kHz in width. In cluttered habitats and when the bats were turning the call was more than 15 kHz in width. Prey was only detected when there was no overlap between the emitted call and the received echo. The soprano pipistrelle emits two types of social calls; a complex song-like call when at the mating roost and in the foraging habitat, and a cheep-like call during flight (Pfalzer & Kusch, 2003). Click here to listen to the social call of the soprano pipistrelle. Size of sound file: 35.9 KB The social call of the soprano pipistrelle has three components. This can be used to distinguish the common from the common pipistrelle, which has a social call of four components (Barlow & Jones, 1997).
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Status and Protection The decline in Europe of many bat populations, including that of the soprano pipistrelle is often partially attributed to the use of agricultural chemicals in the intensification of agriculture. The recent increase in the number of organic farms in the UK has facilitated comparative studies between organic farms and conventional farms. A study by Wickramasinghe et al. (2003) found that the dominant species on both conventional and organic farms were the common and soprano pipistrelles, both species were more common on organic farms. Back to top
© School of Biological Sciences, University of Bristol 2005. Last modified 24th February 2005.