Whilst 24 of the surveyed devils were one year old, 16 were two years old and a further three were three years old. Devils in the wild rarely live beyond five years and with the pressure of DFTD, even fewer have been making it into old age. The presence of older devils at the site is something to celebrate. The results from ongoing monitoring at this site and numerous others around the state will hopefully shed some light on the mechanism for this apparent increase in density, and whether it is likely to be sustained.
Although prevalence of DFTD cannot give us a full measure of the overall health of a devil population, ongoing monitoring means that trends can be identified and will inform the direction of the STTDP. Targeting hotspots, the STDP has installed fencing which sounds an alarm and warns wildlife of approaching cars. The number of devils hit has dropped by a quarter and Tasmanian pademelons and Bennett's wallabies have also benefited.
The government has also been trialling a new app since July that members of the public can use to report sightings to help monitor populations. So far, the app has been downloaded by over 2, users who have entered 6, reports. In the curious case of the Tasmanian devil, there is much still to be learned about cancer biology and the evolutionary arms-race between malignant cells and their hosts.
The sheer speed of the decline has created a strong selective pressure on the world's largest remaining carnivorous marsupial but it now seems hope could lie in co-existence. Image source, Getty Images. Image source, Dr Max Stammnitz.
Tumours can become as large as half the size of the face. Sometimes the tumours grow inside the mouth and can push out teeth. This makes it difficult for the devil to eat.
Death results from starvation and the breakdown of body functions as a result of the cancer. In diseased areas, nearly all sexually mature Tasmanian devils older than two years of age become infected and succumb to the disease. Juveniles as young as one year old can also be infected. We used mathematical modelling techniques to see whether different strategies — such as more frequent or more intensive trapping — could have made this approach work.
Furthermore, after infection, the tumours take time to grow and become detectable the current best estimate is around six months. There is, however, reason for hope.
Scientists from a staggering range of fields are working hard to learn more about the devil and its disease. In the fight against DFTD, knowledge is power. Knowledge about how the devil fits into the wider ecosystem could help uncover ways to help the devil in its own fight against the disease. The disease is now entering the north-west of Tasmania, where devil populations are subtly different genetically from those in eastern Tasmania, where the disease first arose. We have indications the disease is increasing much more slowly in these Western populations and is having less effect on devil populations.
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