Rakali Watch 1999 Results
 
 
By Michelle Smith
 

The population of the Rakali (water rats) inhabiting the St.Kilda Breakwater between the kiosk and the second set of steps has been observed by volunteers from Earthcare since October 1997. The population is highly visible, and volunteers are able to study the feeding and social behaviour of the animals. Identification of distinctive marks on individual Rakali is awkward due to inadequate light, the presence of rocks and waves, and their swimming style (mostly submerged). It has therefore been difficult to estimate the size of the population, although we believe there are about 20 animals that call the breakwater "home". Trapping and ear tagging has been carried out periodically, with three individual Rakali captured. Certain measurements are taken to determine the age of captured Rakali, including the lengths of the body, tail, hind foot, ear and the white tip of the tail. The condition of both the coat and the animal is also assessed

The table below illustrates the animals that have been captured and tagged. Rakali are generally trap shy, and we have had many instances where an individual has encountered a trap and run off with fright. To combat this "trap avoidance", it is common to leave traps for a few days prior to setting them, to enable the animals to become accustomed to the sight and smell of them. Unfortunately, we are unable to leave traps unattended at St. Kilda due to the potential for theft or vandalism, and so we are hoping that persistence will eventually pay off!

 
SEX
WEIGHT
BODY
TAIL

HIND FOOT

EAR
TAILTIP
NOTES
               
F
742 GRAMS
244 MM
278 MM
64.4mm
13.6mm
-
Ran into rocks under bollard 4
               
F
734 grams
245mm
284mm
61.5mm
5.8mm
95.3mm

Good condition. Rocks b/w bollards 1&2

Tag # 3426

               
F
AS Above
-
-
-
-
 
Recaptured after 5 minutes
               
M
835 grams
300mm
250mm
67mm
-
115mm

Good condition, docile. Trapped well under boardwalk

Tag #3427

  As can be seen in this table, three Rakali have been captured, although the study team has approximately 15 – 20 sightings per night. We have tried trapping at full tide, half tide and low tide, and have decided to concentrate our efforts during periods of half tides. We have also found that rough, choppy conditions hamper the sighting of Rakali in the water, and they are less active on very windy nights.  
 
To join the Rakali Study Group or get more information

ST. KILDA BREAKWATER

between the kiosk and the second set of steps.

The monitoring of the Rakali has enabled us to determine some patterns of behaviour. They emerge at around dusk, and are living amongst the rocks underneath the entire boardwalk. They tend to swim out to one of the pylons (where we presume they are prying off mussels or tube worms to eat), or to the pier, where we generally lose sight of them. They may also be obtaining mussels and tube worms from the pylons that hold up the pier. On their return to the boardwalk, they often get out of the water at the seagrass beds and browse around. They then walk along the beach, or swim along the beach in the shallow water. It is during this time that we can observe them running back and forth along the beach, and in some instances they are only a metre or two away.
We have observed them eating mussels, fish and tube worms (and a nice diet of seafood-flavoured catfood when in the traps), and they tend to either eat on the "Feeding rock" or on the beach, although the Totally Wild crew shot footage of one swimming on its back like an otter, while eating a tube worm at the same time. Analysis of prey remains in the feeding tables they leave behind indicate that they also eat a proportion of crabs and other shellfish. They have also been observed climbing the chains and ropes of boats that are moored at the marina. They are usually solitary, but we sometimes see them interacting, and at this time of year the young should be starting to get out and about.
So if you want to see one of Australia’s most attractive rodents in their natural environment, please come along and give us a hand. Rakali Watch takes place approximately twice a month (depending on tides and weather), so keep an eye out in the next issue of Earthcare News for the dates, and come and discover the exciting world of the Rakali at the St. Kilda breakwater
 
 
An Introduction to Rakali
 
 
Rakali Biology
 
 
Rakali Life Style
 

Contact Earthcare PO Box 287 Elwood, 3184

copyright Earthcare St Kilda 2006

Email earthcarestkilda@gmail.com