Platypus are air-breathing mammals, and by choice spend
up to 17 hours a day resting out of the water in an underground burrow.
However, they feed only in the water and are rarely observed on land for
more than a few minutes at a time. Many of the platypus found in unusual
locations, such as suburban gardens, appear to be young animals that are
orphaned or have dispersed from their mother's home range in order to claim
their own territory.
What do platypus burrows look like?
Platypus use two types of burrows: "nesting burrows"
(which provide shelter for a mother and up to three offspring) and "camping
burrows" (all other burrows). In both cases, the burrow chambers are just
big enough to accommodate their occupants - for example, a nesting chamber
containing two young platypus (estimated to be a month old) along Lockyer
Creek in Queensland was 25 centimetres wide x 46 cm long x 20 cm high, while
a camping chamber known to be used by a subadult male along Badger Creek in
Victoria was 20 cm wide x 30 cm long x 14 cm high.
The tunnel leading to a camping burrow chamber is usually
quite short (1-4 metres long). Camping burrow entrances are usually difficult
to spot, being located underwater or just at the water's surface and often
hidden by overhanging vegetation or an undercut bank.
Where are platypus burrows found?
Platypus select burrow sites partly on the basis of
bank height, with nearly all burrows found in banks rising one metre or
more above the water.
As well, platypus prefer to place their burrows along
moderately undercut banks where substantial vegetation overhangs the water.
Such banks are normally well consolidated by plant roots, so that undercutting
is confined to the part of the bank extending just above (as well as below)
the water surface. The amount of cover provided along the bank top by shrubs
and low-growing plants has also been found to be significantly greater than
expected at platypus burrows located along the Yarra River near Melbourne.
Besides helping to protect platypus burrow entrances from predators, this
combination of habitat characteristics reduces the likelihood that burrows
are damaged by erosion.
How many burrows does a platypus
use?
An adult platypus will normally occupy several different
camping burrows (up to about a dozen) within a period of a few weeks.
By having numerous burrows scattered across the entire length of its home
range, a platypus is always reasonably close to a safe refuge. As well,
using different burrows on different days may reduce the proliferation of
parasites (such as the platypus tick, Ixodes ornithorhynchi) at any one location. Two grown platypus will sometimes share
a burrow at the same time, though males and females both tend to be solitary
in their habits.
Do platypus ever spend the day resting
in places other than burrows?
Radio-tagged platypus have occasionally been found sleeping
inside a hollow log at the edge of the water or within a pile of woody branches
accumulated in the stream channel.