Hystrix It. J. Mamm. (n.s.) 22(1) 2011: 159-166

Pag. 158 disegno THE WINTER DIET OF THE LESSER HORSESHOE (RHINOLOPHUS ) IN BRITAIN AND IRELAND

CAROL WILLIAMS1*, LEO SALTER1 and GARETH JONES2

1Cornwall College, Camborne Pool Redruth Campus, Cornwall, TR15 3RD, U.K; present address: 10 Treveryn Parc, Budock Water, Falmouth, Cornwall TR11 5EH *Corresponding author, E-mail: [email protected] 2School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, U.K 3The Open University, Walton Hall, Milton Keynes, MK7 6AD, U.K

Received 8 September 2010; accepted 20 March 2011

ABSTRACT - The lesser Rhinolophus hipposideros feeds regularly through- out the winter across its British and Irish range. During winter 1995/96 and 1998/99, in Cornwall R. hipposideros fed mainly on dipteran in the families Tipuli- dae/, and . Differences in dietary composition were found across the British and Irish range of R.hipposideros in winter, and these proba- bly relate to local differences. Nevertheless, across sites Tipulidae/Trichoceridae were always the most frequently eaten prey in winter, with Mycetophilidae and Anisopodi- dae also eaten frequently. The of the important prey families indicated the value of damp woodland with decaying wood and grazing , particularly cattle, for the winter foraging of R. hipposideros.

Key words: foraging, faecal analysis, dipterans, conservation

RIASSUNTO - Dieta invernale del rinolofo minore (Rhinolophus hipposideros) in Bre- tagna e Irlanda. Il rinolofo minore Rhinolophus hipposideros si alimenta regolarmente in inverno nel suo areale britannico e irlandese. Durante gli inverni 1995/96 e 1998/99, in Cornovaglia questa specie aveva una dieta costituita principalmente da ditteri appartenenti alla famiglie Tipulidae/Trichoceridae, Sphaeroceridae e Micetofilidi. Differenze nella com- posizione della dieta invernale sono state trovate attraverso il suo areale, probabilmente im- putabili alla diversità degli habitat locali. Tuttavia, nelle zone esaminate i Tipulida- e/Trichoceridae erano sempre le prede più frequentemente consumate in inverno, seguite da Micetofilidi e . Tenendo conto dell‟ecologia dei ditteri maggiormente consu- mati, le aree invernali di foraggiamento del rinolofo minore erano indicativamente i boschi umidi con legno in decomposizione e animali al pascolo, in particolare bovini.

Parole chiave: foraggiamento, analisi delle feci, ditteri, conservazione

DOI: 10.4404/Hystrix-22.1-4498

INTRODUCTION pended in foraging. For small insecti- vorous the energetic costs of flying For an to feed successfully, the can be as high as 21 x their basal meta- amount of energy acquired from feed- bolic rate (Racey and Speakman 1987) ing needs to be greater than that ex- and 600 x higher than the energy con-

159 Williams et al. sumption in (Avery 1985). Dur- and across the range in Britain and Irel- ing the winter period (from October to and. April) when abundance in tem- perate regions is reduced, bats enter hi- MATERIALS AND METHODS bernation (prolonged torpor). Hiberna- tion is punctuated by arousals from tor- 1. Faecal analysis por, although the frequency of arousal varies among and individuals Faecal pellets were collected at fortnightly (Menaker 1964; Daan 1973; Funakoshi intervals from a R. hipposideros night roost and Uchida 1978a; 1978b; Ransome in a cellar/boiler room of a small manor house, situated at the head of a valley that 1990). The exact cause of arousal is leads down to a tributary of the Helford uncertain (Park et al. 2000) but temper- River, Cornwall (50° 7‟N; 5° 8‟W). The ature in the roost plays a part. Arousal collections were made, from the same site, can lead to foraging if temperatures are throughout two winters, 1995/96 and sufficiently high and if other climatic 1998/99. The boiler was in use during the conditions are suitable (Ransome 1971, study and resulted in temperatures in the 1990; Avery 1985; Duvergé and Jones range of 13°C to 18°C. Polythene sheeting 1994). was placed on top of the boiler and faecal Because insect activity, temperature pellets and any discarded insect fragments and bat arousal are correlated (e.g. (such as wings and legs) fell onto the sheet and were collected. From each fortnightly Jones et al. 1995), bats may feed more collection, a random selection of 20 pellets often in parts of Britain that are mild was taken for analysis. during the winter (see Ransome 2002). The pellets were left to soak in water satu- Cornwall is in the extreme south west rated tissue paper for at least 4 hours and of Britain, and experiences a maritime then added with a few drops of glycerine climate and Rhinolophus hipposideros into a petri dish to aid the separation of the (IUCN Near Threatened status) feeds fragments contained in the pellet” (Shiel et regularly throughout the winter. In al. 1997). Using a headless entomological coastal regions of Cornwall, winters are pin, the pellet was then gently teased apart in the glycerine until the fragments that it very mild with temperatures falling be- contained could be readily seen under a low freezing only infrequently (2-23 Brunel MX-7T low power stereomicros- days/winter with air frost, 1971-2000: cope (magnification x 40) once mounted on Meteorological Office, Exeter, U.K.), a microscope slide.. Under the microscope, and winter foraging by R. hipposideros all fragments were identified to and is expected to be common. most to (Tab. 1). The identification At present knowledge of the diet of R. was carried out with the aid of various hipposideros is restricted to summer handbooks and keys (Skidmore 1991; Un- feeding (Beck et al. 1989; McAney and win 1991; Chinery 1993; Shiel et al. 1997). Tipulidae and Trichoceridae have been Fairley 1989; Hollyfield 1993; Beck grouped together as it is only if antennal 1994/5; Arlettaz et al. 2000). None of sections are present that it is possible to these studies have examined prey taken distinguish between them, and their habitat during winter foraging. The work re- needs are largely the same. Similarly Chi- ported here addresses this situation by ronomidae and have been the analysis of species diet in Cornwall grouped together. A list of all recognizable

160 Williams et al. Winter diet of lesser horseshoe bats sumption in torpor (Avery 1985). Dur- and across the range in Britain and Irel- families was made for each faecal pellet in Cornwall and therefore the results are ing the winter period (from October to and. and from this a percentage frequency of the not as comprehensive. The results are pre- April) when insect abundance in tem- prey families found could be calculated for sented as a total of all sites for Devon, perate regions is reduced, bats enter hi- MATERIALS AND METHODS each fortnightly period. Percentage fre- Wales and Ireland for winter 1998/99. quency is the number of occurrences of a bernation (prolonged torpor). Hiberna- category, divided by the total occurrences 1. Faecal analysis RESULTS tion is punctuated by arousals from tor- of all categories, multiplied by 100%. The por, although the frequency of arousal presence of () can be a Faecal pellets were collected at fortnightly In winter 1995/96, Diptera were by far varies among species and individuals source of bias because scales remain intervals from a R. hipposideros night roost the most frequently occurring order (Menaker 1964; Daan 1973; Funakoshi in the digestive tract for long periods (Whi- in a cellar/boiler room of a small manor (86%; Tab. 1). Sphaeroceridae (24%) and Uchida 1978a; 1978b; Ransome taker 1988; Robinson and Stebbings 1993). house, situated at the head of a valley that This could lead to an overestimation of the were the most frequent family, fol- 1990). The exact cause of arousal is leads down to a tributary of the Helford importance of moths in the diet if all pellets lowed closely by Tipuli- uncertain (Park et al. 2000) but temper- River, Cornwall (50° 7‟N; 5° 8‟W). The containing scales are counted. In this work dae/Trichoceridae (23%). Mycetophili- ature in the roost plays a part. Arousal collections were made, from the same site, in order to accommodate this problem only dae (12%) and (11%) can lead to foraging if temperatures are throughout two winters, 1995/96 and a moderate to large amount of scales, or also occur in significant numbers. sufficiently high and if other climatic 1998/99. The boiler was in use during the scales along with other remains of moth Changes in diet were relatively small study and resulted in temperatures in the conditions are suitable (Ransome 1971, classified the pellet as positive for Lepidop- range of 13°C to 18°C. Polythene sheeting (Fig. 1a), though be- 1990; Avery 1985; Duvergé and Jones tera. was placed on top of the boiler and faecal came scarce after the end of December. 1994). A reference collection of , caught in pellets and any discarded insect fragments Due to the large number (21) of catego- Because insect activity, temperature a similar habitat to that surrounding the (such as wings and legs) fell onto the sheet ries involved at a low occurrence, in and bat arousal are correlated (e.g. roost some 4.5 km distant from it, was and were collected. From each fortnightly Fig. 1 those below a percent frequency made using a suction trap. Trapping was Jones et al. 1995), bats may feed more collection, a random selection of 20 pellets carried out on an approximately fortnightly of 5% are shown in the „others‟ catego- often in parts of Britain that are mild was taken for analysis. basis (avoiding nights with rain) by a John- ry. In winter 1995/96, this includes during the winter (see Ransome 2002). The pellets were left to soak in water satu- son-Taylor 12 inch insect suction trap, Araneida () and Oniscidea Cornwall is in the extreme south west rated tissue paper for at least 4 hours and which was put into operation half an hour (woodlice) which both indicate glean- then added with a few drops of glycerine of Britain, and experiences a maritime after sundown and left functioning until ing as a mode of feeding. Acari () into a petri dish to aid the separation of the climate and Rhinolophus hipposideros dawn the following day. were also noted in the diet but it was fragments contained in the pellet” (Shiel et (IUCN Near Threatened status) feeds al. 1997). Using a headless entomological found that Sphaeroceridae, when regularly throughout the winter. In 2. Collection of faecal pellets from across pin, the pellet was then gently teased apart trapped, were host to Acari and this coastal regions of Cornwall, winters are the British range of R. hipposideros in the glycerine until the fragments that it could be the mode by which Acari en- very mild with temperatures falling be- contained could be readily seen under a tered the diet of R. hipposideros. Faecal pellets of R. hipposideros were col- low freezing only infrequently (2-23 Brunel MX-7T low power stereomicros- lected during a nationwide annual survey of In Cornwall, in winter 1998/99, Dipte- days/winter with air frost, 1971-2000: cope (magnification x 40) once mounted on ra were still the predominant order Meteorological Office, Exeter, U.K.), hibernacula organised through the Bat a microscope slide.. Under the microscope, Conservation Trust (BCT). The collection (78%; Tab. 1). Tipulidae/Trichoceridae and winter foraging by R. hipposideros all fragments were identified to order and of a sample of „fresh‟ R. hipposideros faec- formed the largest category (24%), fol- is expected to be common. most to family (Tab. 1). The identification al pellets was made during visits to hiber- lowed by Mycetophilidae (13%) and At present knowledge of the diet of R. was carried out with the aid of various nacula where this was possible without handbooks and keys (Skidmore 1991; Un- Sphaeroceridae (12%) The percent fre- hipposideros is restricted to summer causing disturbance. These samples were quency of the latter, as so as that of feeding (Beck et al. 1989; McAney and win 1991; Chinery 1993; Shiel et al. 1997). analysed by the same procedure used for Tipulidae and Trichoceridae have been Scathophagidae (from 11% to 3%), was Fairley 1989; Hollyfield 1993; Beck pellets collected in Cornwall. Similar col- evidently lower than in winter 1995/96. grouped together as it is only if antennal lections were made in western Ireland. The 1994/5; Arlettaz et al. 2000). None of sections are present that it is possible to In contrast, increases were apparent for these studies have examined prey taken sample sizes for this part of the study (often distinguish between them, and their habitat 10 pellets analysed per collection) were not Lepidoptera (7% to 12%), which were during winter foraging. The work re- needs are largely the same. Similarly Chi- as large as those used in Cornwall nor were the predominant category in January ported here addresses this situation by ronomidae and Ceratopogonidae have been the samples collected as frequently (be- (Fig. 1b), Anisopodidae (3% to 11%) the analysis of species diet in Cornwall grouped together. A list of all recognizable tween one to five collections per winter) as and Neuroptera (2% to 5%).

161 Williams et al.

Figure 1 - Seasonal changes in the percentage frequency of prey groups eaten by R. hippo- sideros during winter in Cornwall during 1995/6 (a) and 1998/9 (b).

162 Williams et al. Winter diet of lesser horseshoe bats

Table 1 - Dietary composition of prey eaten by Rhinolophus hipposideros as measured by percentage frequency from samples collected from Cornwall, Devon, Wales and Ireland; Cw = Cornwall winter; Dw = Devon winter; Ww = Wales winter; Iw = Ireland winter.

Cw Cw Dw Ww Iw 1995/6 1998/9 1998/9 1998/9 1998/9 Number of sites 1 1 5 2 6 Number of droppings analysed 280 260 45 56 42 Class Order Family Arachnida Acari 4 <1 Araneae Araneidae <1 <1 1 <1 Insecta Coleoptera 1 <1 1 3 Dermaptera <1 Diptera Anisopodidae 3 11 18 Chironomidae/Cerato <1 1 7 8 15 Culicidae 1 7 1 Doliocoptidae 1 3 <1 <1 1 Lonchopteridae <1 <1 4 Mycetophilidae 12 13 14 1 Muscidae/Calliphorid <1 2 11 17 Platypezidae <1 1 4 Psychodidae 2 4 7 Scathophagidae 11 3 3 4 7 <1 5 9 Simulidae 7 7 6 Sphaeroceridae 24 12 4 10 <1 Tipulidae/Trichocerid 23 24 19 11 2 Hemiptera Aphidoidea 15 20 1 <1 Lepidoptera 7 12 4 3 5 Neuroptera 2 5 8 10 3 Psocoptera 12 1 Trichoptera <1 3 7

Results for Devon, Wales and Ireland which uses faecal analysis to investi- (Tab. 1) show in all cases Tipuli- gate the diet of bat species but ethical dae/Trichoceridae as the most frequent- considerations mean that faecal analy- ly occurring category, followed by My- sis is the only viable option. cetophilidae and Anisopodidae in De- The main source of bias in faecal anal- von and Ireland, while Neuroptera, ysis is the over representation of hard- Mycetophilidae and Sphaeroceridae bodied prey over soft-bodied insects were most prevalent in the diet at (Belwood and Fenton 1976; Rabino- Welsh sites. witz and Tuttle, 1982; Kunz and Whi- taker 1983; Dickman and Huang 1988).

Figure 1 - Seasonal changes in the percentage frequency of prey groups eaten by R. hippo- DISCUSSION However, in this study because the ma- sideros during winter in Cornwall during 1995/6 (a) and 1998/9 (b). jority of the diet of R. hipposideros is Sources of bias can exist in any study small soft-bodied prey, this has not been

163 Williams et al. as important a source of error as it sulted in many cattle farmers (particu- would be for other bat species. larly the smaller, less intensive farms) Faecal analysis could also be non- diversifying into other areas of farming representative because not all faecal and often ceasing to farm cattle. Al- pellets from winter foraging would be though sheep dung does also have an deposited at the night roost; rapid di- associated insect fauna it is not as ex- gestion makes it likely that some would tensive as that of cattle where each cow be deposited whilst still out on the wing pat may contain up to 1,000 developing (Hoare 1991; Robinson and Stebbings insect larvae, principally Diptera (Cox 1993). However, the time spent forag- 1999). Møller (2001) found that the ab- ing each evening is greatly reduced in undance of barn swallows Hirundo rus- winter (Williams 2001) so any bias due tica decreased by 48% when dairy to this effect should be minimised. The farming ceased and sweep netting indi- value of faecal analysis is supported by cated that this was due to insect density blind tests on the reliability which con- being significantly lower in the absence cluded that faecal analysis yields rea- of cattle. sonable estimates of food eaten (Kunz Also endectocides have an adverse ef- and Whitaker 1983). The analysis of fect on the dung fauna. Strong and bat droppings is now generally consi- James (1992) found that 50% of Scato- dered to yield reliable information on phaga stercoraria were killed within the diet of insectivorous bats, as long as 48 hours of exposure to Ivermectin at a sustained scrutiny for fragments is concentration found in cattle dung maintained (Shiel et al. 1997). treated with a slow-release bolus, Although with some variation due to while, at lower levels, abnormal devel- local differences in climate and insect opment of insect fauna can occur availability, our results were consistent (Sommer et al. 1992). throughout the British range of R. hip- Within the winter foraging range of R. posideros, pointing out the importance hipposideros, which is reduced by ap- of some families of Diptera, especially proximately 50% to their summer range Tipulidae/Trichoceridae Mycetophili- and has a mean radius of 1.2 km around dae and Sphaeroceridae, for the winter sites (Williams 2001), con- feeding of this bat species. servation measures should include the Mycetophilidae are often found in retention of native broad-leaved wood- woodland - particularly ones land and damp areas and the promotion which are not managed to remove rot- of hedgerows and other linear features ting wood. Damp woodland with de- and winter grazing, particularly by - caying vegetation also support larvae of tle, where conditions permit.. Where the Tipulidae (crane flies) and Tricho- conventional farming is practiced, the ceridae (winter gnats), as those of Ani- use of endectocides, particularly bolus sopodidae (window midges). application, should be avoided. The life cycles of Sphaeroceridae and Scathophagidae is associated with dung ACKNOWLEDGEMENTS (Skidmore 1991; Cox 1999). In recent years in the United Kingdom, low pric- We would particularly like to thank roost es fetched by beef and the “Foot and owners Lucie Nottingham and Peter and Mouth disease crisis” in 2001 have re- Mary Forty. Marian James helped with in-

164 Williams et al. Winter diet of lesser horseshoe bats as important a source of error as it sulted in many cattle farmers (particu- sect identification, as did Peter Skidmore, ous . J. . 69: 108- would be for other bat species. larly the smaller, less intensive farms) Martin Harvey, Peter Chandler, Tony Hut- 113. Faecal analysis could also be non- diversifying into other areas of farming son, Adrian Spalding, Alan Stubbs and Duvergé P.L., Jones G. 1994. Greater representative because not all faecal and often ceasing to farm cattle. Al- Robin Howard. Chris Hall, Kate McAney, horseshoe bats - activity, foraging be- pellets from winter foraging would be though sheep dung does also have an Sylvia Bevis, Keith Davies, John Kacza- haviour and habitat use. Br. Wildl. 6: deposited at the night roost; rapid di- associated insect fauna it is not as ex- now and Jean Matthews sent droppings 69-77. gestion makes it likely that some would tensive as that of cattle where each cow from around Britain and Ireland. The Ho- Funakoshi K., Uchida T.A. 1978a. Studies be deposited whilst still out on the wing pat may contain up to 1,000 developing nourable Vincent Weir has provided the on the physiological and ecological majority of the funding for this research adaptation of temperate insectivorous (Hoare 1991; Robinson and Stebbings insect larvae, principally Diptera (Cox along with English Nature (now Natural bats. Hibernation and winter activity in 1993). However, the time spent forag- 1999). Møller (2001) found that the ab- England) through their Species Recovery some cave-dwelling bats. Jpn. J. Ecol. ing each evening is greatly reduced in undance of barn swallows Hirundo rus- Programme. 28: 237-261. winter (Williams 2001) so any bias due tica decreased by 48% when dairy Funakoshi K., Uchida T.A. 1978b Studies to this effect should be minimised. The farming ceased and sweep netting indi- REFERENCES on the physiological and ecological value of faecal analysis is supported by cated that this was due to insect density adaptation of temperate insectivorous blind tests on the reliability which con- being significantly lower in the absence Arlettaz R., Godat S., Meyer H. 2000. bats. Annual activity of the Japanese cluded that faecal analysis yields rea- of cattle. Competition for food by expanding pi- house-dwelling bat Pipistrellus abra- sonable estimates of food eaten (Kunz Also endectocides have an adverse ef- pistrelle bat populations (Pipistrellus mus. J. Fac. Agric. 23: 95-115. and Whitaker 1983). The analysis of fect on the dung fauna. 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