TECHNIQUE

Hand-rearing Insectivorous Bats (Wildlife Casualty Management)
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Summary Information
Type of technique Health & Management / UK Wildlife Casualty Management / Techniques:
Synonyms and Keywords N.B. This information should be read in association with Hand-rearing of Orphaned Wildlife which contains background information together with links to the Electronic Library and Organisations (UK Contacts). The related Species pages contain similar linkages.
Description This page has been prepared for the "UK Wildlife: First Aid and Care" Wildpro module, and is designed for the needs of the following species: Bechstein's bat - Myotis bechsteinii, Brandt's bat - Myotis brandtii, Brown long-eared bat - Plecotus auritus, Daubenton's bat - Myotis daubentonii, Greater horseshoe bat - Rhinolophus ferrumequinum, Grey long-eared bat - Plecotus austriacus, Large mouse-eared bat - Myotis myotis, Lesser horseshoe bat - Rhinolophus hipposideros, Noctule - Nyctalus noctula, Lesser noctule - Nyctalus leiseri, Nathusius' pipistrelle - Pipistrellus nathusii, Natterer's bat - Myotis nattereri, Northern bat - Eptesicus nilssoni, Particoloured bat - Vespertilio murinus, Pipistrelle - Pipistrellus pipistrellus, Serotine - Eptesicus serotinus, Western barbastelle - Barbastella barbastellus, Whiskered bat - Myotis mystacinus

The UK bat species are from the families Rhinolophidae, Vespertilionidae.

  • Juvenile bats are most likely to be found July to August.(P19.1.w7)
  • Hand-rearing of an insectivorous bat should not be undertaken unless absolutely necessary. (B168.7.w7)
  • If a baby bat is found every effort should be made to return it to its roost.

Returning a baby bat to its roost

  • Initial rehydration before returning the baby, using water or oral rehydration solution, may maximise the chance of survival.
  • Locate the roost if at all possible.(B168.7.w7)
  • Return the baby into the roost if possible. (B168.7.w7)
  • The baby may placed at the roost entrance if possible, otherwise as close as is possible. If the roost is not accessible the baby may be placed near the roost, where it may be picked up by the mother, attracted by the infant squeaking.(P19.1.w7, J3.128.w1)
  • Place the baby where the mother can reach it but local cats cannot.(B231)
  • If it is not picked up (should happen at dusk when the bats emerge from the roost) the baby may be kept warm and hydrated, before trying again the following night. (P19.1.w7)
  • The attempt to return the baby to its mother should be repeated on two or three consecutive nights.(P19.1.w7, B168.7.w7)
  • If the roost appears temporarily empty if should be checked regularly and the baby returned to the roost immediately if the adults reappear.(B168.7.w7)
  • N.B. In the UK in order to enter a known roost (including a bat box being used by bats) it is necessary to have an appropriate licence (B168.1.w1).
  • Contact your local bat group or bat worker via the Bat Conservation Trust for advice.

Initial Care: 

General mammal information: 

  • On arrival any young mammal should be weighed, warmed, stimulated to urinate/defecate and given fluids by an appropriate route to counteract dehydration. 
  • The age should be determined if possible. (See individual species information pages, sections "Appearance - Neonate" and "Life Stages - Reproductive stages").
  • The first feed given should be an oral rehydration (electrolyte) solution (e.g. Lectade, Pfizer Limited), with a gradual changeover to a milk substitute over several feeds. 
  • See: Hand-rearing of Orphaned Wildlife for further general information.

Insectivorous bat specific information:

  • Initial feed of oral rehydration solution such as Lectade (Pfizer Limited).(J3.128.w1, D24)

General Care (including warmth and hygiene):

General mammal information

  • Young mammals have poor ability to maintain body temperature and are prone to hypothermia, hyperthermia and burns, particularly when unfurred or only sparsely furred.
  • Keep out of draughts but ensure ventilation is adequate.
  • Provide a temperature range, e.g. by heating one end of the container more than the other, which, while not allowing either overheating or chilling, permits the animal to chose the position at which it feels most comfortable.
  • The container used should be sufficiently large to allow the occupant to move into a comfortable position.
  • Bedding materials should be soft, comfortable and either disposable or easily washed. They should keep the animal dry and be changed as frequently as necessary to prevent soiling.
  • (B194, P3.1987.w5, V.w5)

Insectivorous bat specific information:

  • The following have been suggested as appropriate temperatures:
    • Maintain at an ambient temperature of 34C or greater (J3.128.w1).
    • Keep warm (25-28C) after feeding to encourage digestion.(B168.7.w7).
    • Keep at 30C after feeding to ensure milk digestion.(B231)
  • Cleaning should be needed only if large amounts of milk are spilt onto the bat during feeding. (B168.7.w7)
  • The bat's face may be cleaned with cotton buds if milk is spilt during feeding.(B231)
  • A paintbrush may be used to both wash and dry the baby bat.(B231)
  • Accommodation similar to that for adult bats may be provided: a plastic box with kitchen paper draped over the inside walls for grip, a tight-fitting well-ventilated lid and heating provided by a mat under one end of the container or heating along one side.
  • A furry "mother substitute" should be provided for the infant to cling to.(B224)

Milk replacer:

  • Avoid changing the type of milk being used or mixing different milks.(B168.7.w7)

Suggested milk replacers include:

  • Esbilac (Pet Ag), mixed one part powder to one part water.(B151)
  • Esbilac (Pet Ag) (although some workers have reported problems with bloat). (B168.7.w7)
  • Goat's milk or cow's milk, with frequent feeds.(J3.128.w1)
  • Fresh cow's milk has been used, also powdered skimmed milk with a 1-2% fat content, possibly with added glucose.(B168.7.w7)
  • Goat's or cow's milk, diluted three parts milk to one part water for the first week.(B231)
  • Supplementation:
    • Supplement milk with multivitamins (Abidec).(V.w26)

Utensils:

  • Small paintbrush.(B151)
  • Very small pipette, or a small catheter attached to a small syringe.(B168.7.w7, B224, B231)

Feeding Frequency:

General mammal information: 

  • Varies depending on species.
  • In general, every 2-3 hours during the day and longer intervals at night.(P3.1987.w5)
  • More frequent feeding (e.g. every hour) may be required for very small species, particularly for neonates.(V.w5)

Insectivorous bat specific information:

  • "Frequent feeds". (J3.128.w1, B224)
  • From 7.00am to 11.00pm, feed every two hours. Leave overnight.(B151)
  • As many as eight feeds a day - may be possible to reduce to as few as four feeds a day if using Esbilac (PetAg).(B168.7.w7)
  • Every two hours during the day and a break of no more than 4-5 hours at night, initially. Five or six times daily after the first week.(B231)

Feeding Technique: 

Small mammal information:

  • To encourage feeding in very small animals, place a drop of milk on lips, preferably with animal held upright.(P3.1987.w5)
  • To feed using a medicine dropper:
    • Hold the infant in one hand with its head slightly higher than its body, place the dropper just inside the animal's lips and press the bulb extremely gently to place a tiny drop of formula in the infant's mouth to encourage feeding to start. As it begins to suck or lick the dropper may be pressed very gently to assist the infant to take the formula.(B194)
    • If a bubble of liquid appears at the nose or the infant opens its mouth wide, immediately stop feeding and tilt the infant head down to allow the excess formula to drain from its mouth. Give the infant a chance to recover then start again more slowly.(B194)
    • Refill the dropper as required.(B194)
    • Some infants may feed by licking individual hanging drops of the end of the dropper.(B194)
    • Clean any excess from the infant's nose/chin after each feed.(B194)
  • A similar technique can be used with a small syringe, pressing very slowly on the plunger as the infant sucks or licks.(V.w5)
  • When feeding very small neonates it is vital that the feeding technique used provides milk at a sufficiently slow rate to minimise the risk of milk being inhaled with resultant aspiration pneumonia. (V.w26)

Insectivorous bat specific information:

  • Feed from a very small pipette, or a small catheter attached to a small syringe. (B168.7.w7, B224, B231)
  • Allow to lap milk from a fine-tipped paintbrush. This method enables the bat to exert greater control over the rate of milk intake and may therefore reduce the likelihood of aspiration pneumonia. (B151, V.w26)

Quantities:

  • General mammal information: Energy intake (kilocalories per day) = 200-250 x weight(kg) 0.83. (P19.1.w5, P3.1987.w3)

Toileting: 

General mammal information:

  • Most infant mammals require gentle stimulation of the ano-genital area (using e.g. a damp cotton bud, damp cotton wool or damp soft paper towel) in order to urinate and defecate. This should be done when the animal is first presented and at every feed until voluntary elimination is observed.

Insectivorous bat specific information:

  • A paintbrush may be used to stimulate urination and defecation.(B231)

Weighing: 

General mammal information:

  • Weigh daily. 

Insectivorous bat specific information:

  • Accurate weighing is particularly important during weaning.

Weaning:

  • Wean to mealworms gradually at 2-3 weeks, initially mixing milk and mealworms, offering the insides of mealworms on a paintbrush at two weeks and reaching the consumption of whole mealworms by three weeks.(B231)
  • The insides of mealworms (larvae of Tenebrio molitor beetles) can be squeezed out and the baby allowed to lap.(B151, B168.7.w7)
  • Alternatively, mealworm fragments may be added to the milk, with more added gradually.(B168.7.w7)
  • Later whole mealworms may be given: the bat must be taught to eat these and eventually to eat them from a bowl.
  • Some juveniles appear reluctant to wean from milk to mealworms diet and perseverance is important.(B168.7.w7, J23.10.w1)

Release:

  • Until recently it was considered that hand-reared insectivorous bats should never be released as they would lack necessary survival skills such as catching live prey in flight.
  • The Bat Conservation Trust guidelines on bats in captivity suggest that hand-reared baby bats should not be released into the wild.(B168.7.w7)
  • Work in the USA has shown that hand-reared bats are able to successfully echolocate and catch prey in flight and suggests release may be successful.
  • Some bat workers in the UK are now releasing hand-reared bats.(B151)
  • A soft release technique should be used if hand-reared bats are to be released. 
  • See: Release of Casualty Insectivorous Bats
Appropriate Use (?)
  • Returning a baby bat to its roost is preferred whenever this is possible.
  • Hand rearing is appropriate for a baby bat known to be orphaned (mother known to be dead) or an apparently "abandoned" baby which it has not been possible to return to its roost.
  • Wild animals should not be taken for hand-rearing unless they are definitely orphaned, abandoned or injured, or in immediate danger.
Notes
  • Cross-fostering onto another bat is unlikely to be successful.(B168.7.w7)
  • Carrying the baby around or frequent handling may assist in hand-rearing, possibly by substituting for the normal warmth and physical contact in a bat colony.(B168.7.w7)
  • Gentle massage of the stomach may be useful if digestive problems develop. (B168.7.w7)
  • Hand-reared bat babies grow more slowly than do wild individuals. (B168.7.w7)
  • Time to begin weaning should be judged depending on the size of the bat and the fusion of its phalangeal epiphyses.(B168.7.w7)
  • Careful monitoring (e.g. of weight and growth) is vital during weaning. (B168.7.w7)
  • Studies in the USA have shown that hand-reared bats can learn to catch insects on the wing, at least within the confines of an aviary.(B230)
  • An ordinary outdoor thermometer may be used to indicate the temperature in the container used for rearing.(B194)
  • Routine records should be maintained of daily weight, times of each feed, quantities of milk consumed, urine/faeces production and general condition/demeanour. Such records provide an objective means of assessing progress and provide useful data for improving rearing methods.(V.w5)
  • Practice with fine control of a syringe is required to enable milk to be given a drop at a time.(V.w5)
Complications/ Limitations / Risk
  • Wing bone distortion may occur if levels of calcium in the diet are inadequate. (J3.128.w1)
  • The Bat Conservation Trust guidelines on bats in captivity suggest that hand-reared baby bats should not be released into the wild.(B168.7.w7)
  • Hand-reared bats will not have had a chance to learn feeding and roosting as they would do from members of their social group in the wild. (J3.128.w1)
  • Handling should be minimised for a juvenile bat which is intended to be released back into the wild.(B168.7.w7)
  • N.B. some workers have reported problems with bloat while using Esbilac (Pet Ag). (B168.7.w7)
  • Re-sterilised syringes should be discarded when the plunger begins to stick as the additional pressure required to move the plunger may result in excessive quantities of fluid being accidentally deposited in the infant's mouth. (V.w5)
Equipment / Chemicals required and Suppliers
  • Feeding utensils, as required:
    • Syringe and fine blunt-ended catheter.
    • Small pipette.
    • Paint brush.
  • Milk replacer:
    • Esbilac canine milk replacer (Pet Ag, Kruus UK Ltd., Unit 17, Moor Lane Industrial Estate, Sherburn in Elmet, North Yorkshire, LS25 6ES; Pet-AG Inc., Elgin, Illinois, USA) from pet stores.
    • Goats' milk: Many supermarkets and health food stores
    • Cows' milk: Supermarkets, corner stores etc.
  • Lectade (Pfizer Limited): From veterinary suppliers.
  • Abidec multivitamin drops: from chemists.
Expertise level / Ease of Use
  • Hand-rearing of bats is considered "difficult, time-consuming and often disappointing". (B168.7.w7)
  • Hand-rearing of bats should preferably be carried out by someone who has experience with bats. It should be possible to contact a local bat group or bat worker for advice via the Bat Conservation Trust.
  • Considerable time commitment involved.
  • Manual dexterity is important for caring for these very small individuals.
  • Requires empathy, observation skills and the ability to "read" the animal's body language.
  • Experience with hand-rearing is useful and likely to greatly increase the success rate.
Cost/ Availability
  • Products and equipment all widely available, not particularly expensive.
Legal and Ethical Considerations
  • Every effort should be made to return an apparently-orphaned baby bat to its roost.
  • If it were considered that a hand-reared bat would not be releasable into the wild, it would have to remain in captivity and would therefore require lifelong accommodation; euthanasia should be considered if suitable long-term accommodation is not likely to be available.
  • Hand-reared bats will not have had a chance to learn feeding and roosting as they would do from members of their social group in the wild.(J3.128.w1)
  • Hand-reared bats may be investigated under the Wildlife and Countryside Act 1981 to ensure that the bat is not being kept illegally. The onus is on the holder of the bat to prove that the bat has been acquired legally.(J3.128.w1)
  • Hand-rearing should not be started unless the carer is prepared to give the time and effort required for rearing to release, or to ensure that appropriate care will be continued through to release.
  • Consider whether hand-rearing is the best option for the individual compared with leaving it in the wild.
  • Consider whether euthanasia is a more humane/kinder option for the individual than attempting hand-rearing.
  • An offence may be committed under the Abandonment of Animals Act 1960 Section 1 if a released animal does not have a reasonable chance of survival (i.e. a chance similar to its non-rehabilitated peers). It is an offence under this Act for a person having control or charge of an animal to abandon it permanently or otherwise in circumstances likely to cause unnecessary suffering. This may include release at an unsuitable site, in the wrong territory, unfit, not having learned to hunt, at the wrong time of year etc. (J35.147.w1, B156.21.w21, B223, W5.Jan01)
  • A licence is required if a known bat roost (including a bat box which is or has been used by bats) is to be entered.(B168.1.w1)
  • See: Legislation relating to Wildlife Casualties
Author Debra Bourne
Referee Becki Lawson and Suzanne Boardman
References

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