Echidna love trains
Echidnas breed in winter so, at this time of year, they're out and about on the lookout for a mate. Lovelorn male echidnas often queue up behind a female, nose to tail, forming long trains, up to ten echidnas long. These trains are the first part of the strange echidna courtship and mark the begining of the breeding season.
Echidnas are Australia's most widely distributed mammal. They live almost anywhere from semi-arid regions to wet mountainous forests and their only real requirement is a good supply of small invertebrates, ants and termites which they eat with their long sticky tongue.
Despite echidnas marketing appeal — for example, 'Millie' the echidna mascot of the 2000 Olympic Games in Sydney — there are still many things we don't know about their natural life.
Although widespread, they're not a common sight in the bush for most of the year. They're mostly solitary, elusive animals. With highly sensitive hearing and a good sense of smell they're easily able to avoid unwelcome company, even of their own kind. So the coming together of echidnas for breeing is quite a sight and a relatively rare chance for us to view echidnas in the wild.
Along with platypuses, echidnas are the only living members of an ancient order of mammals, the monotremes.
Most mammals are therians, which give birth to live young.
Last century, echidnas caused an uproar among scientists when in 1884 a Scottish naturalist William H. Caldwell announced to the British Academy that monotremes lay eggs. At the time it was even proposed that humans evelved from reptiles.
Even today, the evolutionary origins of the monotremes are still a scientific puzzle.
Dr Peggy Rismiller began studying echidnas in 1990 at Pelican Lagoon Research and Wildlife Centre on Kangaroo Island in South Australia. She's one of very few people to have seen echidnas mating.
When: Echidnas breed in Winter
Where: Echidnas are Australia's most widely distributed mammal. They live almost anywhere from semi-arid regions to wet mountainous forests and their only real requirement is a good supply of small invertebrates, ants and termites which they eat with their long sticky tongue.
Other info: Lovelorn male echidnas queue up behind a female, nose to tail, forming long trains. These trains are the first part of the strange echidna courtship and mark the begining of the breeding season.
The most likely time to catch sight of them is around dusk or dawn when they're out foraging, although in southern Australia in winter they can also be out and about in the middle of the day.
Echidnas don't like to get hot and, depending on where they are in Australia and the time of the year, they'll change from day active to night active.
They'll also go into caves or burrows and drop their body temperature to ambient levels.
One of the best signs that an echidna is about is the mark they make with their snout in soft sand and soil when they're searching for food, a small triangular furrow with a round hole at its apex.
Also they have distinctive cylindrical blunt ended scats (faeces), about the size of human's small finger.
Making love in a rut
Echidna trains can last anywhere up to 6 weeks before mating eventually happens. During this time the echidnas can be seen walking, foraging and just simply resting together.
Echidna trains can have any number from two to 11 echidnas, though three to four is more usual. The males sometimes move from one train to another.
The males follow the female and sometimes make advances by nudging her tail or side with their nose. When the female signals that she's ready to mate another colourful display of the echidna's sexual behaviour begins the mating rut.
The female stops and often partially digs her front legs and head in near the base of a tree or bush. The male echidnas start digging a trench beside the female. They then try to push each other aside, and end up digging around the bush as well as beside the female. The result is a doughnut-shaped rut which about 18-25 centimetres deep. The rings have puzzled many a bushwalker
Eventually the males begin pushing each other head to head until only one remains in the trench with the female. Mating finally begins, with the male having dug slightly under the female. He turns on his side and they mate cloaca to cloaca.
If there is only one male, the mating ring becomes a simple straight trench. Ever versatile, echidnas can also mate below ground.
On Kangaroo Island, Peggy Rismiller has found that females only breed every three to seven years and not until they're about five to seven years old.
The amazing puggle
Baby echidnas are called puggles. They start life when the mother lays an egg about 22 days after mating.
Getting an echidna egg from the cloaca to the pouch, is not an easy feat and no-one's actually seen it happen. However Penny Rismiller has occasionally seen echidnas sitting upright on their tails without any support for their backs, while they use their snouts to groom their belly fur. She says that in this sitting position a female echidna's cloaca could extend to reach into the folds of the pouch.
Once in the pouch it's 10 days before the baby echidna hatches. Only 1.5 centimeters long, its hind legs are just buds, but the front legs already have tiny claws that can hold onto the mother's pouch hair. The egg is usually in the far end of the pouch and so the tiny echidna must travel around six times its own body length to get its first drink of milk.
The milk comes from two 'milk patches' located on each side of the front end of the pouch where a nipple would normally be found. Echidnas don't have teats for the hatchlings to attach to.
Young puggles grow incredibly fast. They can increase their weight six hundredfold, from three to 180 grams in 60 days. The mothers spend a lot of time foraging for food to keep up the milk supply.
Puggles begin to outgrow the pouch and grow spines when they're about 7 weeks old. The young echidna is then put in a nursery burrow where it spends about five months, with the mother returning only about every five to 10 days to feed it. In one feeding though a burrow young can drink up to 40 per cent of its body weight.
At seven months old, the weaned burrow young are left totally on their own. Unlike most mammals, the mother just leaves and will even avoid them.
How many young echidnas survive?
Echidnas live a long time: up to 45 years in the wild. Are Australia's echidnas an aging population with fewer and fewer young echidnas surviving? We do not know.
Australia has only one species, (Tachyglossus aculeatus) the short-beaked echidna, but its appearance varies around the country. There are five subspecies which are identified by the length of their spines, how hairy they are and the relative length of their third hind claw as compared to the second. In Tasmania the fur between echidnas spines can be so long the spines are almost hidden
New Guinea is the only other place on the world that has echidnas.
The Australian short-beaked echidna also lives there in the lowlands and another species, the long-beaked echidna (Zaglossus bruijni) is found only in the New Guinea highlands. It's bigger and scavenges in rainforest litter.
Echidnas like a lot of space. On Kangaroo Island their home range varies from about 40-88 hectares. However in other parts of the country this can be much larger. In Western Australia up to 198 hectares has been recorded. Ranges can overlap but there's no interaction between individuals. If they meet up they just ignore each other.
Echidnas don't have a home den. They can have five or more burrows as well as making use of natural shelter in crevices and caves, and they don't follow regular paths, all traits that make studying them very difficult.
When young echidnas are weaned they move out of their mothers home range. Peggy Rismiller has tracked one young echidna who moved 40 kilometres away. Land clearing and habitat fragmentation may have made it much more difficult for young echidnas to move to suitable new habitat.
The echidna is an amazing digging machine. On soft ground if faced with danger echidnas can literally dig themselves in vertically. They use their front claws in a rotational movement and simply sink from sight. Also, Echidnas can swim!
On hard ground they will simply curl up if a predator attacks. Mostly their spines are an excellent deterrent but cats and foxes are a problem for both young and adult echidnas. In the Kangaroo Island study area cats kill 20 per cent of the burrow young. Goannas are a natural predator of the young.
To sleep perchance to dream
It's long been thought that the echidna was the only mammal that did not dream. But now the echidna has neuroscientists thinking hard about the evolution of REM sleep, the type of sleep where we dream.
In February this year Stuart Nicol and his colleagues from the University of Tasmania found that echidnas do experience REM sleep, so long as they're at the right temperature. At 25°C they experience REM sleep, but at 28°C or 15°C it decreased or disappeared.
On top of all this the prefrontal cortex of the echidna's brain is larger compared to the rest of its body than any other mammal including man. Usually the greater the volume of the this part of the brain, the "more advanced" is the animal.
Echidnas are highly individual in many ways.
At 33°C, echidnas have the lowest active body temperature of all mammals except the platypus. Most mammals daily body temperature only varies by a degree or so, but the echidnas can fluctuate by up to 6–8°C, dropping down to 28°C without any problems.
They're very adaptable in their use of torpor, an energy saving strategy which they can use at any time of the year.
In 1987 Gordon Grigg and Lyn Beard and Michael Augee radio tracked echidnas living in Kosciuszko National Park and were the first to describe hibernation in montremes. The echidnas dropped their body temperature to 4°C and reduced their breathing rate to one breath every three minutes. Every couple of weeks they would warm up over about a 12-hour period to a normal active temperature then soon fall back to near ambient temperatures, the same pattern of hibernation as seen in placental mammals.
The fact that echidnas hibernate has important evolutionary implications. Many scientists see hibernation as 'primitive', that mammalian hibernation in winter is a reversion to reptilian metabolism. Others think it's a very advanced ability.
The echidna is evolutionarily old, having split from other mammals over 120 million years ago but it certainly doesn't fit easily into our ideas of what is primitive and what is evolutionary success.
Managing echidna populations
No-one really knows how many there are now in Australia and how well they've adapted to environments altered by white settlement.
The echidna is listed as common, could they be becoming more endangered? We don't really know.
Other unanswered questions include environmental threats. What threat do cars and electric fences pose to echidnas? What effect are pesticides and herbicides having on echidnas by killing their food sources?
Echidna Watch< is a nationwide survey that coordinates sightings and other information sent in by people all over Australia. So if you come across an echidna in the bush or even while you're camping or picnicking in the park, post your observations on the Echnida Watch Website. Even the most brief and casual observations can be useful.
Echidnas do sometimes turn up in suburbia. Don't assume they are lost, just keep away the cats and dogs and the echidna will usually move off following a creek line or some vegetation. Another way of becoming involved in echidna research is through Earthwatch. Earthwatch volunteers are an important part of echidna research on Kangaroo Island.
- Rismiller, Dr. Peggy D. The Echidna - Australia. s Enigma. (1999) Hugh Lauter Levin Associates, Inc. ISBN 0 88363 788X
- Rismiller, Dr. Peggy D. and McKelvey M. Frequency of breeding and recruitment in the short-beaked echidna, Tachyglossus aculeatus". Journal of Mammalogy Vol 81 No.1 February 2000, pp 1-17
- Rismiller, Peggy D. and McKelvey M. (1996) Sex, torpor and activity in temperate climate echidinas. Pp 23-30 in "Adaptations to the cold" (F. Geiser, A.J. Hulbert and S.C. Nicol, eds). University of New England Press.
- Rismiller, Peggy D. and McKelvey M. (1994) Orientation and relocation in short-beaked echidnas, Tachyglossus aculeatus multiaculatus. Pp 227-234 in "Reintroduction biology of Australian and New Zealand fauna" (M. Serena, ed). Surrey Beatty & Sons, Chipping Norton
- Rismiller, Peggy D (1992) Field observations on Kangaroo Island echidnas (Tachyglossus aculeatus multiaculatus) during the breeding season. Pp101-105 in "Platypus and echidnas" (M.L. Augee, ed). The Royal Zoological Society of NSW, Sydney.
- Rismiller, Peggy D. and Seymour, Roger S. The Echidna. Scientific American February 1991
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- Grigg, Gordon and Beard Lyn. Heart rates and respiratory rates of free-ranging echidnas . Evidence for metabolic inhibition during hibernation?
- Pp 13-22 in "Adaptations to the cold" (F. Geiser, A.J. Hulbert and S.C. Nicol, eds). University of New England Press.
- Grigg, Gordon, Beard, Lyn and Augee, Mike. Hibernation in a monotreme, the echidna (Tachyglossus aucleatus), Comparative Biochemistry and Physiology, Volume 92A, No. 4, pp 609-612, 1989
- Grigg, Gordon, Beard, Lyn and Augee, Mike. (1992) Thermal relations of free-living echidnas during activity and in hibernation in a clod climate. Pp. 160-173 in "Platypus and echidnas" (M.L. Augee, ed). The Royal Zoological Society of NSW, Sydney.
- Grigg, Gordon, Beard, Lyn and Augee, Mike.(1992) Reproduction by echidnas in a cold climate. Pp 93-100 in "Platypus and echidnas" (M.L. Augee, ed). The Royal Zoological Society of NSW, Sydney.
- Ralph, Lynda. Echidna Ecology. Australasian Science, Winter Issue Volume 18 Number 2 1997.
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- Stuart Nicol , Niels Andersen, Nathan Phillips, and Ralph Berger.
- The echidna manifests typical characteristics of rapid movement sleep. Neuroscience Letters Volume 283 (2000) pp 49-52
- Robert Kanigel. Australian Mammal is Researcher. s Dream. Chicago Tribune, March 22, 1987
Published 01 June 2000