(kim) 25 Disease Cats on Marion + a few randoms

Question 1

Sustained control by disease

Cats on Marion island

• 290km breeding area for seabirds on S. Indian ocean
• 5 cats brought in to control mice in 1948

(3,045 cats by 1977)

-Mortality petrel chicks 100% in 1979-84

What to do?

Answer 1

-Cats fully seseptibe to type of fatal cat flu

1977: Cat flu imported

1977-82: Cats reduced by 29%

(Antibodies to diesease developed by cats)

1982: Rate of disease declined by 8%

Human response - switch strategy

86-90: 872 cats shot

-443 in 1st season, only 32 in last

1988-90: 80 cats trapped

(last season figures in relation to cats wising up to humans and guns. Cats started avoiding people meaning harder to kill)

Question 2

How to justify sustained control

• Huge funds wasted unless well justified
• Biology of resource must be well understood

Source and reason for damage clearly identified

Alternative explanation ruled out

Control operation well planned and executed

No unexpected consequences, especially bad ones

Effects recorded, benefit to resource confirmed

Answer 2

• Huge funds wasted unless well justified
• Biology of resource must be well understood

Source and reason for damage clearly identified

Alternative explanation ruled out

Control operation well planned and executed

No unexpected consequences, especially bad ones

Effects recorded, benefit to resource confirmed

Question 3

Mesopredator release

-Removing top predator > lots more 2nd level predators

Situation becomes worse because 2ndary predators usually smaller, therefore more abundant, potentially more damaging

Cat-kiore-petrel example best because effects on birds well documented

Won’t happen with A24’s, which kill both rats and stoats

Other examples

Waihaha - remove possums > more ship rats

UK, Russia, probs also NZ - remove stoats > more weasels

USA (remove wolves > more cayotes)

Answer 3

Remove stoats = hard to do and little effect

Remove possums alone = Rats increase

Remove possums + remove rats = Mice increase

Absolutely everything is connected in nature. You cannot do only one thing without affecting another

To get rid of them all is a big ask unless you have a way of preventing them from getting back (Maungatautari Southern Enclosure)

Question 4

Fenced sancturies

Pros and Cons?

Answer 4

Pro:

Reduce use of:

• Traps
• Poisons
• Massive regeneration inside of flora and fuana

Cons:

• Very expensive
• Vulnerable to break ins, fence breaches
• Mouse heaven, so very attractive to mustelids

(Mustelids can smell the mice poo which draws then close)

-Attractive target for sabotage

All in all, despite cons…

GREAT SUCCESS!