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RATS!

RATS!. Rachel Fewster Steven Miller James Russell Hamish MacInnes Department of Statistics University of Auckland. Aotearoa New Zealand is unique. Home, sweet home. Aotearoa New Zealand is unique. Home, sweet home. ... and under threat. There are no native land mammals in New Zealand.

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RATS!

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  1. RATS! Rachel Fewster Steven Miller James Russell Hamish MacInnes Department of Statistics University of Auckland

  2. Aotearoa New Zealand is unique Home, sweet home

  3. Aotearoa New Zealand is unique Home, sweet home ... and under threat.

  4. There are no native land mammals in New Zealand. CATS POSSUMS FERRETS GOATS PIGS HUMANS MICE DEER RATS STOATS Native birds can’t compete!

  5. RATS are among the worst HABITAT DESTRUCTION COMPETITION PREDATION VANDALS! THIEVES! MURDERERS!

  6. There are three rat species in New Zealand:

  7. 1. Ship rats: Rattus rattusThe Climbers

  8. 2. Norway rats: Rattus norvegicusThe Swimmers

  9. 3. Kiore (Pacific rat): Rattus exulansThe first and smallest All three species originate from Asia.

  10. How to tell them apart? • First look at the foot: Kiore have a brown diamond on the foot.

  11. Then look at the tail: • Ship rats have long tails for climbing! • Norway rats have shorter tails, pale underneath.

  12. Ship rats are most common • Norways are bigger but less common • Kiore are much less common All three species are present in the Bay of Islands

  13. Rats are everywhere in New Zealand How do they get there? Even on islands

  14. How do they get there? 1. Swimming They do it deliberately

  15. How do they get there? 2. Boat rides Moored boats are easy swimming targets

  16. How do they get there? 3. Cling to driftwood

  17. How do they get there? 3. Cling to driftwood

  18. How do they get there? 4. Conspiracy Our aim is to understand rat movements, for best protection of sanctuary islands

  19. Our research at the University of Auckland: Closely related rats mean lots of swimmers! Unrelated rats mean isolation. Use genetics to see how much movement there is between different islands

  20. If we eradicate rats on an island... and replace by threatened birds... will we get a reinvasion?

  21. Basic idea: Populations that are isolated from each other have different genetics. e.g. people in Germany... ...look different from people in Italy.

  22. RATS RATS ? ? ? RATS Same with rats: We might be able to tell from their genetics. Are rats swimming between different islands?

  23. ? ? ? Same with rats: If an island is truly isolated… RATS RATS RATS …the genetics of its rats may differ from other islands. RATS

  24. ? ? ? Same with rats: If islands are linked by regular swimming… RATS RATS RATS We use genetics to see how much rats are swimming between islands. …their genetics may be very similar.

  25. First we had to catch some rats....

  26. The Fieldworker’s Problem

  27. Catching rats…. …is not as easy as it sounds! Fieldwork Rat: Rattus catchus ifyoucanus

  28. But even worse… …there are some unwanted side effects…

  29. So we asked DoC to catch some rats for us instead.

  30. 500 rats caught in total! • Norway rats hold the islands • Some ship rats and kiore on the islands • Ship rats hold the mainland DNA from 300 Norway rats sent to the lab

  31. These ship rats on Urupukapuka are new since the 1980s DNA from 80 ship rats sent to the lab

  32. Months of work for Hamish MacInnes, our lab scientist, to test the genetics of nearly 400 rats We use the same lab techniques as the police use to solve murders with DNA evidence

  33. What do genetic results look like? We’ll use an example from Aotea, Great Barrier Island ...

  34. Fitzroy Fitzroy region, Great Barrier Island Motu Kaikoura

  35. Fitzroy Each point is one rat; Each colour is a different island Look for: Overlap: closely related populations Separation: isolated populations Fitzroy region, Great Barrier Island Motu Kaikoura Genetic results

  36. Haku Fit Kai Nel

  37. Clear left-right divide: something is stopping the rats from swimming this small gap?

  38. Cliffs at the landing points!

  39. The genetics tell us about rat movements in Aotea Great Barrier Island: What do they say about the Bay of Islands...?

  40. Results: Norway rats Norway rats are good swimmers; BoI has short distances and easy beach landings

  41. OKA WAE URU MAH Massive jumble! Motuarohia is furthest away and slightly different

  42. OKA WAE URU MAH

  43. OKA WAE Conclusion: No island is safe from Norway rats! These results were used to help justify the eradication scheme for all 7 islands simultaneously URU MAH

  44. What about ship rats? Weaker swimmers; Not present on islands in 1980s

  45. Did they swim from Rawhiti? Somehow a population of ship rats established on Urupukapuka in the last 20 years

  46. Kerikeri Urupukapuka Rawhiti Kerikeri Rawhiti Mainland rats from Kerikeri to Rawhiti Ship rat results Urupukapuka rats are totally different!

  47. Kerikeri Urupukapuka Rawhiti Mainland rats from Kerikeri to Rawhiti Ship rat results This invasion happened by boat! Mainland rats are related over 80km distance

  48. Kerikeri Urupukapuka Rawhiti Conclusion: We need to deal with the risk of rats arriving by boat. We don’t think ship rats swam the 800m gap from Te Rawhiti to Urupukapuka. Kerikeri Urupukapuka Rawhiti

  49. The Bay of Islands has wonderful conservation potential

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