- Capture and handling (review)
- Transport (containment, environment)
- Husbandry (housing, environment)
- Experimental procedures
- Release
Much biological research requires that wild animals be taken from nature and held in captivity for some time. Many questions can only be answered by laboratory studies. These laboratory studies may involve breeding animals in captivity.
Obviously, to obtain the best possible results, it is in the interests of the investigator, as well as that of the animal, for the animal to be kept as healthy and happy as possible.
The issues involved with capture are a subset of those covered in Problem 4. Revisit them to refresh your memory.
You have determined that you must capture animals for your laboratory study. Your choice of capture method will be determined by the species and the environment in which you are working. You should use the most efficient method that will have the minimum impact on the animal, both at the time of capture, and for ALL subsequent stages of the study.
Once the animal is captured, you probably will need to handle it and, in many circumstances, you may need to make measurements (e.g. body mass, blood sample). Consider how your method could be refined to minimise impact on the animal, especially through the skill of the operator.
You may need to mark your animal in the field so that it can be identified back in the laboratory. You may also wish to mark the animal prior to its release at the end of the study.
Animals need to be transported from the field to the laboratory if measurements are to be made in the laboratory. Transport is potentially stressful and many factors must be considered.
The Code outlines your obligations when transporting animals. These considerations relate to refinement of your procedures to minimise adverse impacts on the animal.
The factors that need to be considered include the suitability of the container for the species being transported, food and water, noise and vibration, mixing species, time of the journey, security, and sedation.
The container and its environment
The type of container required to transport animals will vary with species. There may be no suitable commercial container available. It is important to provide as comfortable an environment as possible during transportation.
In the design of the container, consideration should be given to:
- suitability of container
An appropriate container (or cage or vessel or bag) is required to contain your animal during transport. For example, very different containers are required for birds, frogs and fish. It goes without saying that the transport cage should provide a safe environment for the animal. That environment may be different from one in which the animal may be held long-term. For example, many animals will be more relaxed if transported a darkened environment.
- possibility of injury to animal
Injuries to animals may occur in many ways during transportation and risks should be minimised. The animal may accidentally injure itself on the container, especially if it is not well designed.
Injuries may also occur when the animals are being place into, or removed from, the container. Ease of access to the animal in the transport container is an important consideration.
- temperature
Very careful consideration should be given to the temperature of animals during transportation. What is a suitable and comfortable temperature for your species during transportation?
Many animals are transported in air-conditioned cars, but if the container receives direct sun through the car window, it may still overheat and distress the animals. Transport by air can be fraught with many dangers.
Will the cage spend time on the tarmac prior to loading? Is the transport hold air-conditioned (and pressurised)?
Forward thinking is required to ensure that your animals do not over-heat, or freeze, during transport.
- humidity
Recognition of the humidity requirements of some animals, and how humidity may change in the transport cage, is important. Some species (e.g. frogs) require very high humidities during transportation, others require low humidities (e.g. most mammals and birds), while some (e.g. many reptiles) are little influenced by changes in humidity.
Remember that evaporation is the only means by which many animals can cool their bodies. In the closed environment of a transport cage, humidity may increase due to respiration and perspiration of the animal. If the humidity increases, the ability to cool evaporatively is reduced.
- air flow
Adequate ventilation of the transport container is important to facilitate gas exchange (respiration) and maintenance of humidity. Some animals (e.g. mammals and birds) have high demand for oxygen and exhale large amounts of carbon dioxide. Adequate ventilation is necessary to maintain high concentrations of oxygen and low carbon dioxide.
Some animals (e.g. reptiles and frogs) have relatively low metabolic rates, so that oxygen concentrations are unlikely to be depressed and carbon dioxide is unlikely to build up, even when the animals are maintained in cloth bags. Aquatic animals, especially those that respire with gills, such as fish, may require their water to be constantly aerated during transport.
- light/dark
Many animals remain calmer if maintained in conditions of subdued light or even complete darkness, whereas some may become distressed in the dark. Careful consideration should be given to the best light conditions for your species.
Husbandry
Husbandry best practice has not been determined for most species. In many cases, the investigator will have more experience with the species than anyone else.
Fortunately, most animal groups have been kept successfully in laboratories or zoos, so probably there will be some experience with similar species. Nevertheless, each species has unique requirements and some experimentation with husbandry to provide ideal conditions to keep the animals healthy may be required. For all species, basic considerations include:
- Housing
- Food and water
- Temperature, humidity
- Cleaning
- Environmental enrichment
- Light
- Sound
- Social needs
- Reproduction
Housing
Specification for suitable caging for many species must be determined on the basis of the biology of the species and previous husbandry experience with the species or its close relatives. In many cases, the caging requirements will be very different from standard laboratory animal housing.
The cage must have adequate dimensions to comfortably accommodate the animal and must be furnished with appropriate bedding and/or refugia.
Many species occupy a three-dimensional space because they are aquatic, arboreal or they fly.
Food and water
Many species require specialised diets. Although the nutritional requirements for most species are not known, basic knowledge of the biology of the animal will provide an idea of the most suitable types of food.
Presentation of the food may be important and a period of training may be required to entice animals to consume a laboratory diet. The common occurrence of obesity in captive animals should be considered also.
Water will need to be provided to most species but the method of provision will vary. For species that are unable to access water from standard rodent water bottle dispensers, water should provided in open containers. However, open containers may result in other problems, such as fouling. Frogs are unable to drink, but require a suitable surface of water for absorption through the skin.
Temperature & Humidity
The thermal and humidity requirements of animals vary widely and the requirements of each species should be considered individually. Even within some major taxa, the requirements vary widely e.g., the upper lethal temperature of some reptiles from cool environments is below the normal operating temperature of others from hot deserts.
For some species, especially the endothermic mammals and birds, provision of constant cool temperatures may be desirable. For other species, provision of a local thermal gradient (e.g. as provided by an incandescent light bulb in a cage of lizards) may be necessary. Some species require daily temperature fluctuations.
Humidity is closely tied to temperature. High humidity reduces the ability of mammals and birds to cool using evaporation, so that humidities should be kept relatively low for many of these animals. In contrast, low humidities may be lethal to frogs. Individual consideration should be given to each species in each circumstance.
Cleaning
Hygiene is important for control of disease, parasites and infection. Cages should be able to be cleaned with minimum disturbance to the animal. Major disturbance of the cage for thorough cleaning may have a negative impact on the animal. Frequency of cleaning will depend on the species, its diet and spillage of water.
For some animals, it is more important to remove uneaten food than it is to clean up excreta. For some species, territorial marking with urine or faeces is important; complete or frequent sterilisation of the cage may cause more problems through stress than the possible health problems associated with the presence of faeces or urine.
Cages can sometimes be landscaped to be largely self-cleaning.
Environmental enrichment
The laboratory environment is much less complex than the wild. Provision of stimulation through enrichment of the environment of the cage may be very important for some species.
Environmental enrichment may take the form of provision of simple toys or complex cage furniture, the hiding of food or landscaping the cage.
Light
Providing the correct lighting regime is important for the well-being of animals. Firstly, a suitable day-night regime must be provided.
The proportion of scotophase to photophase may vary with time of year or by the requirements of the study. If possible, the provision of a twilight at dawn and dusk should be considered. The intensity of light during the photophase may need to be varied from species to species.
Some species, such as small, nocturnal mammals, may be more secure in conditions of subdued light, reflecting their day-time refugia in the wild. In contrast, other species such as diurnal birds may require full strength day light intensity.
The spectral properties of the light will be important to some species, but not others. For example, many juvenile lizards require high intensities of ultra-violet light that would cause problems to other animals, including the investigators.
Sound
An environment free from sudden noises and from the noise of machinery should be provided for animals. Even a ringing telephone can markedly stress captured animals.
The sounds produced by some species (e.g. distress calls or predators) may be stressful to other species
Social needs
For successful husbandry of captive animals, the social needs of animals must be considered on a species by species basis. The sex, age and size of the animals in the colony are important.
Some species or individuals need to be kept isolated from conspecifics, whereas others do better in groups.
Requirements for Reproduction
Factors that facilitate, or suppress, reproduction vary and are not known for most species.
Suppression of reproduction is easy to achieve by maintaining animals in isolation or in single sex groups.
Facilitation of reproduction requires a suitable physical environment, with the necessary environmental cues that may include changes in light cycles and temperature regimes.
The issues involved with release are a subset of those covered in Problem 4. Revisit them to refresh your memory.
In most cases, release of captive animals must be done at the site of capture. After being held in the laboratory for a period of time, however, the first question to ask is, Should this animal be released into the wild?
You should consider whether:
- the animal will survive if returned to the wild.
- release of your animals will upset the new social hierarchy that may have developed since the animal was captured.
- there is any chance of introducing diseases or parasites with the animal.
Note: Your Wildlife Authority permit may preclude release of wild animals that have been held in animal houses.
Appropriate release
If it is inappropriate to release the animal, it may be euthanased at the end of the experiment, retained in breeding programmes, or used for other research.
It is important to select an appropriate method of euthanasia for each species.
It may be appropriate to fix the body and lodge it as a voucher specimen with a museum. In such circumstances, a chemical rather than a physical method of euthanasia should be used.