Paralysis ticks (Ixodes holocyclus) are killing hundreds of Spectacled flying foxes (Pteropus conspicillatus) on the Atherton Tablelands each year. The numbers vary each year, but the majority are during October to December. It's believed to be a fairly recent phenomenon, occurring since about the mid1980s. There is a narrow window of opportunity for the ticks; if the climate is too wet or too dry they cannot survive into adult stage to feed on the bats and other mammals.

During October to December, there are potentially 5 or 6 choices of maternity campsites for the Spectacleds on the Atherton Tablelands. Most are in the higher altitude wetter parts of the Tablelands and one in the relatively drier part of Tolga. They will usually establish themselves at 2 or 3 of these campsites by the middle of October, and leave sometime after the babies are independently flying. Tolga is the exception, it is often permanently occupied throughout the year.

Bruce and Ann Johnson discovered the tick paralysis problem in 1990, though there were reports of unexplained deaths from 1986. They set up the first bat hospital at Whiteing Road followed closely by Pam Tully at Zillie Falls in 1991 and lastly at Tolga by Jenny Maclean in 1997. The 4 maternity camps in the wetter Tablelands were unoccupied from 1998 to 2002 and so the first 2 bat hospitals ceased operations. The flying foxes returned to Whiteing Road colony in 2003 and we now try to monitor this camp as well as Tolga and Powley.

Tolga Bat Hospital -Little Red & Spectacled Flying Foxes
The Little Red flying foxes (Pteropus scapulatus) often camp at these maternity colonies during tick season but are rarely affected, despite roosting lower in the trees. It would seem that the ticks are being picked up at feeding sites rather than roosting sites. Cathy Eggert in her 1994 honours thesis titled 'Is tick paralysis in the Spectacled flying fox related to a change in their foraging behaviour ?' suggests that the ticks may be picked up in tobacco bush, Solanum mauritianum. An attempt by Peter Brice to prove this in 1997 was unsuccessful . Together with Dr Andrew Dennis from C.S.I.R.O we successfuly proved the relationship in 2001 with a grant from the Natural Heritage Trust.

The Spectacleds are throughout the Wet Tropics of far north Queensland but it is only on the high altitude Atherton Tablelands, above 700 metres , that the ticks are a problem . Atherton, and Lismore 1500 kms to the south, are both 'hotspots' for paralysis ticks, flying foxes and wild tobacco but there have only been very isolated cases of tick paralysis in flying foxes in the Lismore region. Spectacleds with tick paralysis are also found occasionally on the coast around Cairns. They could be picking up their ticks on the Tablelands and making the short flight down to the coast.

Information on paralysis ticks is also available on the Friends of far North Queensland Flying Foxes website.

Medical Management of Tick Paralysis

We do not have a resident veterinarian but are supervised by a local vet Dr Wendy Bergen, and before her Dr John McKenzie. We have been involved in research with Prof Rick Atwell from the University of Queensland's Department of Veterinary Sciences. He is probably Australia's leading veterinary authority on tick paralysis. His visit in November 2001 led to improvements in our approach to the treatment of bats with tick paralysis as well as the publication of a paper in the Australian Veterinary Journal in June 2003. Go to www.ava.com.au

 
Assessing the tick bat for ability to swallow and rectal temperature, at the same time! We had a lot to treat that day   Searching the colony.

The basic steps involved in the treatment of tick paralysis are:

  1. Rescue the bat as soon as possible. This means colony searches twice a day if possible.
  2. Remove the tick. There have been many different ideas about how to do this eg poison the tick in situ. We currently remove the tick very quickly by having finger nails of the right length! This is fine if you are practiced and confident.
  3. Keep the bat quiet and unstressed. If bat is female and has young, remove baby and tie coloured wool around ankle of mother and baby for later identification. Keep baby separate and wrapped in cloth with dummy if very young. Deal with any live maggots on baby especially if in eyes.
  4. Decide whether to euthanase bat or proceed with treatment. Signs that indicate the bat has little chance of survival include pulmonary edema, a rectal temperature below 34 degrees centigrade, lack of righting reflex, severe infestation by maggots, a low irregular heart rate and inability to swallow. The normal heart rate in a flying fox is a strong 360 beats per minute, and this can drop to very slow and irregular, or occasionally, the become extremely rapid. It can be difficult to distinguish between the rapid heart and the normal heart. If you decide to treat the bat, offer juice orally slowly through a syringe first. The bat's condition may worsen over the next 24 hours and it be unable to swallow the next day.
  5. Administer tick anti-toxin, about 2.5mls per adult bat . At the same time we also give about 20mls of Hartmann's fluids. We warm the mixture, more so if the bat is cold. We then inject the mix into the peritoneum.
    Provide bat with a comfortable lying down position and the opportunity to grasp on to something with its thumbs. Our cages have mesh on the top and sides.
  6. Offer more juice.
 
Tick paralysed mum, with bub, about to be injected in the colony. If injecting on your own, the stick can help control the bat and prevent being bitten. Most bats lie quietly and do not seem to notice the injection.   Two tick bats sharing one basket. Sometimes on a search, we run out of baskets.

Do not allow bat to try to hang until the heart rate is at least 300 beats per minute. Monitor closely but remember it is a wild animal and will be stressed by too much contact. It may be necessary to administer other drugs under the direction of a veterinarian.

icon   Learn about a typical busy tick season here

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