Feeding of Casualty Insectivorous Bats (Wildlife Casualty Management)

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 Wildlife Casualty & Convalescent Feeding 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.

Fluids (water):

  • Offer a rehydration (electrolyte) solution such as Lectade (Pfizer Limited) to drink on admission once the bat has warmed up.
    • Offer from a paintbrush initially.(V.w28)
  • Water should be freely available at all times unless the casualty is unconscious or severely debilitated and unable to hold its head up.
  • Both water and a rehydration (electrolyte) solution, in separate containers, should be made available initially.
  • (V.w5, V.w26)
  • Water or electrolyte solution may be given initially using an artists brush, blunt-ended catheter tip, as a drip from a finger tip, round ended pipette, soaked cotton wool bud, or by placing the lips of bat on the edge of small receptacle containing water.(P19.1.w7)
  • A shallow dish placed on the floor is an appropriate container for offering fluid to bats.
  • Water bottles with a nozzle as used for rodents may be accepted and used by some individuals, as may the plastic dispensers with a small open section at the bottom used for cage birds.(B168.7.w7)
  • If hand feeding offer water from the moistened tip of a paintbrush or using a blunt-ended catheter after each hand feed.
  • Care must be taken not to supply fluids at too fast a rate which can increase the likelihood of aspiration of fluids.

Convalescent Diet:

Suggested convalescent diets include:

Semi-liquid diet:

  • Body contents of mealworms Tenebrio molitor larvae mixed with water.
  • May need to be given every hour to very weak bats.
  • May be fed using the moistened tip of a small artists brush.
  • (P19.1.w7)

Mealworm contents: As bats become stronger.

  • Squeeze body contents of mealworms directly into the mouth of the bat, having chopped the head off the mealworm.
  • Feed at least three times daily, with as much as the bat will take.
  • Vitamin-mineral supplement e.g. Vionate (E.R. Squibb and Sons Limited) at 1mg per gram of bat per day may be given by applying the supplement to the food immediately before it is eaten.
  • Tinned cat/dog food and scrambled egg have been used in emergencies as a short term diet until more suitable alternatives become available.
  • (P19.1.w7)

Short term Maintenance Diet:

Suggested short term maintenance diets include:

  • Initial feeds generally consist of the insides of mealworms, fed by chopping the head off the mealworm and squeezing the contents into the mouth of the bat.
  • Whole mealworms are used most commonly.
  • Offer bats as many mealworms as they are willing to take in one feed (e.g. 5-10).(V.w28)
    • feed three times daily until the bat starts self-feeding; this is usually about two days for adults.(V.w28)
  • Leave about 20 mealworms on the floor of the bat's container.
    • Killed mealworms should be fed.(V.w28)
  • Bats may need to be taught to eat mealworms:
  • The mealworm is decapitated and held out to the bat in fingers or forceps.
  • Once the viscera have been licked up by the bat, the exoskeleton is pushed into its mouth.
  • While it is chewing, the bat's nose is brought into contact with a dish of mealworms.
  • The dish of mealworms is then left in the cage with the bat.
  • Several sessions may be required to teach the bat to feed from the dish.
  • Free-hanging bats such as Rhinolopus hipposideros - Lesser horseshoe bat, Rhinolopus ferrumequinum - Greater horseshoe bat will not go to a dish on the floor. An elevated dish may be used. It is more likely that hand feeding will be required.
  • The nutritional value of mealworms may be improved if they are kept in dog meal rather than bran, and are supplied with bread and with vegetables rich in ascorbic acid (N.B. bats are unable to synthesise ascorbic acid).
    • Bats may refuse to eat mealworms which have been fed on cabbage.(B168.7.w7)
  • Diets such as Mealworm Diet Calci-Paste (International Zoo Veterinary Group) have been designed for feeding to mealworms to increase their calcium content.
  • A vitamin/mineral supplement such as Nutrobal (Vetark Animal Health), SA37 (Intervet UK Ltd.) or Vionate (E.R. Squibb and Sons Limited- 1mg per gram of bat per day) should be added to the mealworms before they are given to the bats. 
  • Calcium supplementation should be increased for pregnant and lactating bats.
  • Other insects should be added to the diet if possible
    • Moths for Plecotus auritus - Brown long-eared bat, Plecotus austriacus -Grey long-eared bat (moths may be caught using a light trap).
    • Waxworm Galleria mellonella larvae may be useful for juveniles and smaller bat species.
    • Blowfly larvae or pupae. 
    • Early instars of crickets or locusts may be used for the larger species of bats.

Alternative foods:

Suggested alternative foods include:

  • Tinned catfood or dogfood may be used as a substitute if mealworms are not available.
    • The jelly from canned pet food is particularly palatable to some bats.(V.w26)
  • A "bat glop" made from cottage cheese, banana, hardboiled egg, vitamins, + cat or dog food, mixed with a blender to a firm crumbly consistency has been used as a substitute for mealworms, but is considered definitely "second best". (B168.7.w7)
    • If such a mixture is used, some mealworms must still be given as chitin in the diet appears to be important for digestion.
  • (B168.7.w7, P19.1.w7)

In an emergency:

  • Tinned cat food or dog food may be used.
  • Scrambled egg.
  • Chopped or finely grated liver may be used as a short-term substitute.
  • (B168.7.w7, P19.1.w7, V.w26)

Feeding frequency: 

  • May need hand feeding four times daily using tweezers.
  • Leave killed mealworms and other insect larvae as an ad libitum food supply.
    • Insect larvae may be killed by squeezing the head using a pair of tweezers.(V.w26)

Amounts (examples):

  • Provide food ad libitum while rehabilitating casualties.
  • Noctules and serotines (body weight 25-40g) required about 40-58 mealworms per day (8g per day) in summer (e.g. August, September), but only 8g per week in winter when hibernating much of the time.(B168.7.w7)
  • Pipistrelles: recommended amounts vary:
    • A pipistrelle requires about 8-10 mealworms per day in summer. (B168.7.w7)
    • Pipistrelle may eat up to 60 mealworms per day. (V.w28)
  • Doubled quantities are required by lactating females.(B168.7.w7)

N.B. obesity is a recognised problem in bats kept in captivity for long periods of time. Daily weighing and comparison with normal weights for the species should indicate if excessive weight gain is occurring.

(B151, B168.7.w7, B169.15.w15, J3.128.w1, P19.1.w7, D24, V.w26)

Appropriate Use (?)
  • Fresh drinking water should always be available in a container of an appropriate size and type for the species concerned.
  • Fluid replacement therapy other than oral fluids may be required for casualties which are extremely dehydrated on admission or are unable to take in and absorb oral fluids.
    • Fluid therapy should continue until the animal is no longer dehydrated, even if it is self feeding.
  • Feeding of convalescents should take into account their requirement for additional nutrients for healing as well as maintenance requirements.
  • The required fluid intake for maintenance should be considered when designing convalescent diets.
  • Energy requirements for maintenance and healing should be calculated and used to determine the quantity of food required for both convalescence and short-term maintenance diets.
  • Convalescent diets should be easily absorbed/digested.
  • Care should be taken not to under or over supplement with vitamins/minerals.
  • Diets intended for feeding from a syringe or by stomach tube (gavage) must be of a sufficiently fluid consistency to pass through the syringe nozzle or down the tube without it becoming blocked.
  • The natural diet should be considered when deciding on suitable ingredients, including consideration of taste/smell.
  • Fresh food must be provided daily.
  • Regular cleaning of food and drinking water containers (e.g. daily) is important to reduce the risk of disease.
  • Food and water containers should be sited to minimise the risk of contamination with droppings/faeces/urine. 
Complications/ Limitations / Risk
  • Water bowls should not be left in the accommodation of a casualty which is unconscious or is severely debilitated and unable to hold its head up.
  • Dehydrated and malnourished individuals sometimes drink rehydration fluids but refuse plain water initially; others will drink water but not rehydration fluids. Both should be made available.
  • No diet, however well balanced nutritionally, is useful if the animal does not eat it, for example because it is not recognised as food.
  • Ingestion of food should be monitored, not assumed. This may include weighing food before presentation and weighing waste food after removal, and periodic weighing of the animal.
  • Monitoring of weight/body condition is particularly important for group housed/group fed animals, within which some individuals may take more food and others not get the food they require.
  • Diets suggested on this page are intended for short term use for wildlife casualties; they are not necessarily suitable for long-term use or in individuals which are breeding.
  • Diets suggested on this page are not necessarily suitable for feeding infants; information on appropriate diets for very young individuals are described in the page on hand-rearing.
  • If naturally-available food items are gathered for feeding to casualties it is important to be aware of the possibility of contamination with chemical such as herbicides and pesticides.
Equipment / Chemicals required and Suppliers
  • Oral rehydration (electrolyte) solutions are widely available from veterinary suppliers and chemists. 
  • A basic oral rehydration (electrolyte) solution may be made by dissolving one tablespoon of sugar and one teaspoon of salt in one litre of water.(B203)
  • Mealworms and other live foods, and appropriate dietary vitamin/mineral supplements, may be bought from some petshops and from specialist live food suppliers.
  • Mealworm Diet Calci-Paste: (International Zoo Veterinary Group, Keighley, West Yorkshire. 
  • Nutrobal (Vetark Animal Health, PO Box 60, Winchester, SO23 9XN)
  • SA37 (Intervet UK Ltd., Science Park, Milton Road, Cambridge CB4 0FP)
  • Vionate (E.R. Squibb and Sons Limited)
Expertise level / Ease of Use
  • Some experience is valuable when encouraging bats to feed.
Cost/ Availability
  • Mealworms are widely available and not too expensive.
Legal and Ethical Considerations
  • Under the Protection of Animals Acts 1911-2000 it is an offence not to provide animals (including captive wild animals) with necessary food and water.(J35.147.w1, B156.21.w21, B223, P19.2.w1)
  • Care should be taken not to let an individual become accustomed to a single food item as this may result in difficulties in feeding the animal if the food item becomes unavailable, and in preparing it for release.
  • Every effort should be made to provide appropriate natural, locally available foods to animals which have been maintained in captivity for prolonged periods before they are released, in order to re-accustom them to a natural diet and reduce the chance of digestive problems following release.(P24.233.w11)
  • The release of animals which, by virtue of an inadequate or inappropriate diet whilst in captivity, are not fit to survive when released may be considered an offence under the Abandonment of Animals Act, 1960.
Author Debra Bourne
Referee Becki Lawson and Suzanne Boardman

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