Wildlife - Wildlife Release

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California Condor - Conservation

  • In 1987, there were just 27 remaining wild birds
  • Taken into captivity and started a recovery programme
  • Reintroduction began in 1991 and has led to the wild population increasing to around 500 birds
  • Population is consistently monitoring for lead poisoning, without such intervention it is likley the population would crash again.
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Ethics and Legislation of Release

  • At the time of release the animal must be healthy, fit and able to sustain themselves in the wild
  • All animals that have undergone treatment and confinement is the loss of condition and general fitness, with medium-term and long-term detainees suffering from disuse muscle atrophy
  • Overall bodyweight can be brought back to acceptable parameters
    • the muscle to fat ration might still be incorrect
    • adverse effect on survival potential of the individual in the wild
    • stamina and manoeuvrability would be impeded
  • Animal Welfare Act 2006
  • Abandonment of Animals Act 1960
    • An offence under this Act for a person having control or charge of an animal, without reasonable excuse, abandon it permanently or otherwise in circumstances likely to cause 'unnecessary suffering'
    • An offence may be committed under Section 1 of this Act if a released animal does not have a reasonable chance of survival (a chance similar to its rehabilitated peers)
    • This may include release to an unsuitable site, in the wrong territory, unfit, not having learned to hunt, at the wrong time of the year etc.
  • Wildlife and Countryside Act 1981
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Ready to release?

  • Assess casualty-functionally fit
  • Risk assessment
  • Choose a release site
  • Choose a release technique
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Physical Assessment - Part 1

  • Methodical
    • General 'fitness'
    • Limbs
    • Toes
    • Wings function - birds of prey vs. ducks
    • teeth
    • plumage
    • waterproofing and feather/coat condition
    • stamina
    • manoeuvrability
  • a physical disability that is not life threatening for a domestic animal may reduce the ability for an animal to survive in the wild sufficiently to preclude the possibility of release
    • must be physically able to continue all essential parts of its life style, including the ability to gain food
    • depending on the species it may need to be able to hunt, flee from predators or migrate
    • different life styles present requirements for mobility
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Physical Assessment - Part 2

    • the loss of one leg may not preclude release of a relatively lightweight bird which spends most of its time in the air or for some small mammals, but would be very significant for heavy-bodied birds such as swans and for those species spending a lot of time on the ground or perched, as this would increase stress on the remaining leg
    • amputation may considerably increase the risk of developing bumblefoot in the remaining limb
    • even the loss of a toe may be important for a bird of prey which uses its feet for capturing prey
    • mammal species may vary in their ability to adapt to the loss of a front leg compared to the loss of a back leg, depending on their body weight, type of locomotion and tendency to dig/burrow
    • a small decrease in wing function may be vital for most birds of prey which need high manoeuvrability but less crucial for some other species
    • loss of teeth or alteration of teeth function may be very important for predators such as otters and for badgers which depend on their teeth
    • waterproofing and feather/coat condition are important for insulation and are particularly vital for birds with an aquatic lifestyle
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Physical Assessment - Part 3

    • there is a need to assess function by physical examination, but also by observation e.g., flying ability
    • the general 'fitness' level is inevitably likely to be reduced in an animal which has been in captivity for a prolonged period
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Sensory Assessment

  • Must be able to see, hear, smell, taste and touch to be able to obtain food and stay safe
  • Species specific reliance on senses
    • Visual defects in birds of prey
    • Sense of smell in hedgehogs
  • Sensory abilities may need to be tested e.g., observation of negotiating obstacles
  • Ophthalmology assessment for birds
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Reproductive Assessment

  •  Physically able to reproduce at release
  • Inability to reproduce may alter social relationships as they are unable to express natural behaviour patterns
  • Uses up resources of reproductive animals if unable to reduce and still released
  • May outcompete those reproducing if they don’t have the energy demands of reproduction
  •  Females with pelvis fractures may suffer at next parturition
    • Females with pelvic fractures that narrow the lumen of the birth canal should not be released as the animal may be unable to give birth normally and may therefore die at the next parturition/birth
  • May be particularly important for females of social species in which the dominant female suppresses the breeding of other females
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Social/Behavioural Assessment

  • Recognise and integrate into own population
  • Not dangerous to humans/domestic animals
  • Not tame
  • Migratory animals only to be released at the appropriate time of year
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Disease Assessment

  • Risk for individual being released back to infected environment
    • Particular problems for foxes with Sarcoptic mange
  • Risk to wild population from released animal
    • Risk of introducing a novel disease into a wild population may be increased if the casualty is released at a site distant from its original location (except for migratory species released further along their migration route)
    • Screening and testing for some diseases prior to release may be recommended
    •  Considerable costs may be involved in testing for diseases and organ function
  • Reduction of natural immunity (parasites)
  • Underlying issues mean the released animal is unable to cope with the stress of return (organ damage)
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Assessing the Risks

  • Risks to the individual animal
    • Must be healthy and have reasonable fitness at the time of release
    • Released animal may be at risk of contracting disease
    • The environment must offer the animal a reasonable chance of survival in terms of food availability, level of predation, minimal threat from human damage and territory
  •  Risks to the wild population
    • Novel pathogens
    • Disease screening prior to release of casualty
    • May impact one or more individuals of the local population in terms of competition
  • Risks to domestic animals
    • May be at risk of disease
    • At risk of attack from the wild animal that is tame
  • Risks to people
    • At risk of attack from a tame wild animal
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Choice of Release

  • Where found (if practical)
    • Requires accurate data on where the animal originated (e.g., grid reference, road name and house number, description in relation to landmarks)
  • Prolonged rehabilitation may lead to displacement of territory
    • May not be appropriate or possible if the time in rehabilitation has been prolonged
    • Particularly important for territorial animals
    • Release should occur as soon as possible to reduce the risk of the animal being displaced from its territory
  • Sufficient resources
  • Safe (consider initial threat)
  • Consider existing populations
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Legalities, Records and Permissions

  • Permission of landowner
  • Support from the community
  • Keep appropriate records of release
    • Date and time
    • Site
    • Weather
    • Hard/soft
    • Number of animals released
    • Identification marks
    • Follow-up
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Type of Release: Hard Release

  • Exit transport container or let go from hand with no further care or feed provision
  • Easier for rehabilitator
  • For animals in captivity for a short time, or adults, or released back into own territory
  • Not for hand-reared juveniles, or adults maintained in prolonged captivity
  • Consider suitability for animals released at new site
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Types of Release: Soft Release

  • Continue care at release site, reducing resources gradually
  • Commitment of time and effort which may take years
  • For hand-reared and those needing to learn to hunt/gather food
  • Following prolonged care
  • If released in new environment
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Post Release Monitoring

  • Mark the animal prior to release whenever practical
    • Rings, dye, paint, bands, glued plaques, tattoos, radio collars, notches implanted microchips
    • may need a license (e.g., bird ringing)
    • cost?
    • implications on the animals
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Post Release Monitoring-radio and GPS trackers

  •  Radio tracker: physically locate the animal using a receiver. Affordable, reliable, easy to use
  • GPS Tracker: remotely located the animal. Can read at pre-set intervals to track movements. Use mobile phone service or satellites. More power = larger device. Expensive. Drop off mechanism.
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Standard VHF Collars

  • The ‘VHF’ stands for ‘very high frequency’
  • Also known as a pulse collar
  • VHF transmitters attached to a study animal emit a pulsed radio signal allowing a person to physically locate and observe the animal by homing into the signal using a receiver and directional antenna.
  • Advantages: easy to use, reliable, versatile, affordable, can be used on a wide variety of animals, the operating life of the battery can last up to 3 years, available with an internal antenna as an option, for use when there is a high chance of the antenna being chewed.
  • Approximate cost: $350
  • Collars are fitted around the necks of wild dogs, cheetah and lion. Collars are also fitted onto the ankles of black and white rhino
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GPS Tracking Collars

  • Allow for remote location detection of the collared animal’s position
  • The global positioning system is used to record the animal’s exact location and store the readings at pre-set intervals
  • Locations are logged and can then be downloaded in various ways
  • The older GPS collars used to store the data until the collar was retrieved
  • Now, most GPS collars allow the data to be downloaded remotely
  • GPS/GSM collars use GSM cell phone signal to download data
  • Store on board GPS collars can store data which is then downloaded remotely using a handheld UHF device
  • SAT/GPS collars use global satellites to transmit the position and other data to a user’s server/desktop
  • Advantages: data can be collected at any time of day or night remotely and regularly. Most GPS collars are fitted with VHF capabilities so animals can be tracked conventionally, allowing for observational research
  • Disadvantages: need more power to function (adds to total weight), smaller collars operate for less than 12 months, the mobile phone signal is limited in some areas
  • Fitted around the necks of wild dogs and cheetah, and in the form of a harness or ‘back pack’ on vultures, used effectively on the ankles of black and white rhinoceros
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The impacts of short-term monitoring

  • Some early studies on hedgehogs showed a marked weight loss in the weeks after release
  • Concern as to whether released hedgehogs were able to find sufficient food
  • Further research with longer follow-up periods found that the weight loss levelled out
  • Those of highest body weight prior to release were most likely to show marked decreases in weight after release
  • The weight loss was mainly the excess which had been gained in captivity
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