1 / 17

The Rakali – (Eastern Water Rat)

Michelle Smith. The Rakali – (Eastern Water Rat). Rodents of the World Australian rodents Evolution Rakali breeding The Rakali pelt The Rakali diet Habitats Rakali research – Swan Bay. Rodents of the World. Order Rodentia

lel
Download Presentation

The Rakali – (Eastern Water Rat)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Michelle Smith The Rakali – (Eastern Water Rat) Rodents of the World Australian rodents Evolution Rakali breeding The Rakali pelt The Rakali diet Habitats Rakali research – Swan Bay

  2. Rodents of the World • Order Rodentia • Squirrel, beaver, porcupine, guinea pig, capybara, mice, rat • Large, gnawing incisors • Strong jaw muscles • Varied diet, including tough woody plant material

  3. Australian Rodents • 55% marsupials, 22% rodents, 22% bats, 1% monotremes • 61 rodent species – 6 introduced • 4 self-introduced, including black and brown rats, and house mouse

  4. Evolution of the Rakali • 14 genera of native rodents • Most are “Old Endemics” - including Rakali • Rakali in Hydromyinae subfamily – 9 in New Guinea, 2 in Australia • False Water Rat in coastal Nth Qld • Rakali widespread, although patchy • Aquatic niche – fur and feet adapted

  5. Rakali Breeding • Females breed at approx. 5 months age for 3 seasons • Spring / summer breeding in Victoria • 1 – 7 in litter, average of 4 • Blind, short-furred and grey/black at birth, with white tail tip • Eyes open at 14 days, and eat some solids at 3 weeks • Weaned at 4 weeks

  6. The Rakali Pelt • Thermal balance and buoyancy • Colours vary according to geography • All have white tail tip • Black and orange individuals more aggressive • Hunted until 1938

  7. The Rakali Diet • Carnivorous • 2 molars per row instead of 3 – required for crushing hard-shelled prey items • Most prey taken in water • Fish, molluscs, birds, amphibians, insects, lizards, eggs, spiders, yabbies, turtles, crabs, snails, carrion, small mammals, crayfish, crustaceans, rubbish • Climb trees!

  8. Capturing and Consuming Prey • Eyes opened underwater, ears closed • Prey captured and carried in mouth • Prey taken to suitable feeding tables • Leave behind evidence including crab and mollusc shells, yabbie remains, fish scales, bones, feathers etc.

  9. Rakali Habitat • Mainly considered freshwater animal • Inland rivers and irrigation channels • Permanent water bodies • Little research or knowledge of coastal habitats

  10. Rakali Habitats - General • Dense vegetation cover or rocks • Low banks preferable to flat water edge • Stable and friable soil • Semi-submerged hollow logs • Round burrow entrance in bank

  11. Rakali in Coastal Zones • In Victoria, Rakali have been located at: • Melbourne (Williamstown, Port Melb, St Kilda, Elwood, Brighton, Black Rock) • Mornington Peninsula (Sorrento) • Bellarine Peninsula (Clifton Springs, Swan Bay – Queenscliff) • Westernport Bay (French and Phillip islands) • Wilsons Promontory (Corner Inlet)

  12. Rakali Research at Swan Bay • Sandy beaches, mudflats, saltmarsh • Capture – Mark – Recapture • Individually ear-tagged • Animals weighed, measured • Injuries assessed • Released at point of capture

  13. Rakali at Swan Bay • Feeding tables investigated • Prey items identified • Stomach, intestinal and faecal contents examined • Habitat variables defined and analysed • Bank characteristics • Distance • Prey abundance • Plant species • Soils • Veg density • Disturbance • Rocks and logs

  14. Rakali at Swan Bay – Populations • 156 males and 94 females (20 hectares) • Sex ratio of 1.5 males: 1 female • 72% were adults • 33% males with injuries • Male weight – 776g (375g - 975g) • Female weight – 636g (330g – 840g)

  15. Rakali at Swan Bay - Diet • 50% Rock Crab • 20% Mottled Shore Crab • 20% Surf Crab • Other components included: • Smooth Seaweed Crab • Pilchard • Silver Gull • Prickly Toadfish • Smooth Pebble Crab • Shore Crab • Bridled Leatherjacket • Pheasant Shell • No luck with gut analysis

  16. Rakali at Swan Bay - Habitat Coast Saltbush - (Atriplex cinerea) • Saltmarsh vegetation: • Shrubby Glasswort, Beaded Glasswort, Austral Seablite, Coast Saltbush, Marsh Saltbush, Southern Sea-heath,

  17. The End

More Related