ECHIDNAS IN FRED CATERSON RESERVE
by Edwina Laginestra
Echidna - Photo: John Porter
Short-beaked echidnas are found in forests, woodlands, heath, grasslands and arid environments throughout Australia and Tasmania, including in Fred Caterson Reserve. They are monotremes – the most primitive order of mammals; mammals that lay eggs but nurse their young with milk. Monotremes were around with the dinosaurs, 120M years ago, the longest surviving mammals in the world. It is estimated they can live up to 50 years old and their home range could be up to 200 hectares.
The name Echidna comes from Greek mythology after a half-serpent half-woman creature as the first naturalists hadn’t encountered monotremes before (only being found in Australia and New Guinea) and proposed the name as the animal has characteristics of both reptiles and mammals. The local Dharug First Nations people call them gunanguyirngai.
They are sometimes known as spiny anteaters although they aren’t related to the true anteaters. Superficially they resemble spiny animals like hedgehogs, showing convergent evolution rather than genetic similarity.
Their bodies are covered with coarse brown/black hair and have cream/brown/black spines on their backs and sides. The spines are modified hairs and have a role in temperature control. In cooler places like Tasmania, they have thick fur that can cover the spines. They have an elongated slender snout called a beak with a tiny mouth opening, although it is made up of bones of the skull and lower jaw – not keratin like a bird’s beak. The beak has electroreceptors making them efficient at sensing burrowing prey such as earthworms and termites. A long sticky tongue of 17cm is used to catch prey, it can move in and out at 100 times a minute. Prey is crushed between bony plates as echidnas do not have teeth. Their limbs are strong with large claws for digging on their hind limbs, they are the only mammal whose hind feet face backwards.
Echidna showing hind feet facing backwards - Photo: Cathy Woods
Like birds and marsupials, Echidnas have a common opening for urogenital and digestive systems called a cloaca.
They have a low body temperature, but it is heterothermic – their body temperature is variable, usually around 30 degrees C and goes up and down during the day or night, or over a few days. They can go into torpor to conserve energy, rest, heal or in response to trauma. They lower respiration, heart rate, body temperature and metabolism and can drop their temperature by as much as 10 degrees at night. Seasonal torpor may occur during cold weather, poor food availability or extreme weather events such as bushfires.
Echidnas use their beak and strong claws to break open ant and termite nests and lift logs and rocks to find food. They are remarkably strong for their size and many rescuers have struggled to lift them off roads or even tried to rescue them from the surf or waterbodies, but they are strong swimmers and efficient diggers.
They are not sexually mature until 6-12 years old. They may be 2.5kg or up to 5 or 6kg and be sexually mature and they stay at those sizes. As they do not have teats, nipples or external genitals you cannot tell the sex of an echidna without a probe.
They are generally solitary but in breeding season (June to September) they can form “echidna love trains” – the female at the front with several males following and this may last up to 4 weeks. The females breed every 3-5 years – they do not have a proper pouch but the mammary glands swell up on either side of the belly when an egg develops and the egg is laid directly into it. A blind, naked puggle emerges from the egg about 10 days later. Milk is secreted through special pores on the female’s belly. Puggles are suckled in this rudimentary pouch for two or three months. When the puggle develops spines and becomes too prickly, the mother will build a nursery burrow for it. She backfills the burrow when she leaves to feed and returns to feed the puggle only once every 3-5 days for the next 6 months – the puggle takes 10-40% of body weight during these feeds then goes into torpor. The puggle remains in the burrow for around 7 months. Burrows are hard to find and rescuers should always note which way the echidna was heading when it needed a rescue. The mother will not backfill the burrow before she leaves for the last time and the puggle is now left alone to fend for itself.
During fires, echidnas can retreat to burrows or dig into the ground, depending on the soil they may be able to completely bury moving spines to incorporate soil next to the skin for insulation. It will go into torpor to wait out the fire. They have been seen with melted or absent spines which can take years to be replaced naturally.
Adults face threats from motor vehicle accidents during their wanderings, as well as animal attack – dogs, foxes or goannas may attack adults and foxes, cats or birds may attack puggles. If you see an echidna keep pets away (preferably inside) and let them move on in their own time.
Echidna - Photo: Lisa Suykens