Why all Tasmanian devils are born this month


Hobart 7000

The first week of April is a special time for Tasmanian devils, the unique meat-eating marsupials found on Australia’s island state. It’s when life begins for them all and instantly becomes a fight to the death.

Key points:

  • Devils mate at the same time in a “full on” biting, fighting ritual and give birth in the first week of April
  • A mother gives birth to between 30 and 40 joeys but she only has four teats. The first there survive
  • Devils are breeding younger as facial tumour disease changes behaviours in some populations

Due to a regimented and extremely aggressive breeding season in the wild, almost all Tasmanian devils are born in early April.



Photo:

Devil researcher David Hamilton with a young devil. (Supplied: David Hamilton)

University of Tasmania devil researcher David Hamilton said all devils mated in mid-February and March, ready for an April birth.

“That’s the best season to give birth in terms of resources,” Mr Hamilton said.

The devils will stay in the pouch until the end of winter.

“That’s a good time to emerge, so it’s not too cold over winter and it’s not the worst time of year to be starting to fend for yourself and be away from mum,” he said.

A ‘full on’ mating ritual

As for the mating process, Mr Hamilton says it involves a lot of biting and fighting, and some unholy noises.

“The males and the females have pretty ridiculous battles during the mating season,” Mr Hamilton said.

“It’s extremely aggressive.



Photo:

Tasmanian devils have an aggressive mating season, involving long, drawn-out fights. (ABC News: Clarissa Thorpe)

“They’ll bite and claw at one another the whole time and this can last for a few days with the male trying to stop the female leaving dens and things. It can get pretty full on.”

‘Brutal’ selection process



Photo:

Devils shouldn’t mate until they are two years old, but facial tumour disease is changing that behaviour. (Supplied: Department of Environment)

The mother devil has four teats in her pouch, so only four joeys can survive.

“But they give birth to between 30 and 40, and it’s the first four that get to the pouch that make it,” Mr Hamilton said.

“So it’s an early natural selection, which is a bit brutal.”

Most of the surplus devils die after birth, about the size of a grain of rice.

The surviving devils will spend about five months in the pouch, then the mother starts to leave them alone in the den about August.

“She will run back and forth from the den, still feeding them and lactating for them,” he said.

The young devils will spend four or five months in the den, until, weighing a couple of kilos, they are kicked out of home in December and January and become independent.



Photo:

It’s the hunger games from day one as baby devils fight for access to mother’s milk. (Supplied: Caitlin Furlong)

Devil disease changes habits

Mr Hamilton said devils usually don’t breed until their second year, but the facial tumour disease has changed that in some populations.

He said generally the adults would mate, and the young ones forego a season and wait to breed when they are two years old.

“In populations where devil facial tumour disease has been in for a number of years and the adult population has been wiped out, you see a lot of breeding happening in younger animals,” he said.

“They can breed at one [year] in those populations because there’s less competition higher up the chain.”

He said young devils can get bigger quicker because there are more resources.



Photo:

Devil facial tumour disease has wiped out 83 per cent of the population. (Supplied: Rodrigo Hamede )

A new hope

As part of his PhD, Mr Hamilton has been studying wild populations of devils across Tasmania.

The facial tumour disease has wiped out 83 per cent of the wild population.

He said there hasn’t been any evidence of total extinction of populations around the state.

“If you go to areas where the disease has been for 20 years now there’s still devils there, but very low numbers,” he said.

“And we’ve started to see some animals are able to regress facial tumours as well, so they’ll start to develop a little tumour and we come back a few months later and it’s completely gone.

“That’s started to happen in the last few years, but we haven’t seen any signs of population-wide recovery, yet.”



Photo:

Devils leave their mother and become independent at the start of summer. (Supplied: Christo Baars)

Source: https://www.abc.net.au/news