(chris) 20. Controlling invasive mammals with Pesticides Flashcards
Small Beginings
1950-60 - Stowaway rats reach nz smaller islands > threaten sea birds.
1959 - Norway rats invade
1960 - Forest and Bird lay warfarin on Ruapuke, in an attempt to reduce rat numbers and protect nesting birds.
1964 - FIRST SUCCESSFUL ERADICATION OF RATS FROM ANY ISLAND
Unintended but welcome success in eradicating rats showed power of pesticides to control invasive mammals in the wild.
Mammal species controlled with pesticides
-Pesticides currently main weapons against Rats, rabbits, possums and wallabies.
(very cost effective against compared to trapping)
-Secondary poisoning of stoats with rat control
(2 birds 1 stone)
-Goats and less commonly deer also sometimes targeted with pesticides
1080 (Sodium fluoroacetate)
- Occurs Naturally as an anti-herbivore metabbolite in various plants inc. tea but also produced synthetically.
- Metabolic toxin, disrupting biochemical pathways involved in energy production
- Used in NZ since late 1950’s primarily against rats and possums.
- Also used in Aus against foxes, wild dogs, rabbits
(Possums in WA naturally resistant because of 1080 in native plants)
-Used in usa to protect sheep against coyotes (native carnivore)
Why is NZ worlds biggest user of 1080?
- Because we don’t have native mammals where as most places do, this is relevant because mammals are animal most susceptible to 1080!
- Not used by other countries as the 1080 poses a threat to their other native mammals, new zealand uses it as no native mammals to worry about getting caught in the cross fire.
- Native
Birds, Mammals, Fish, Arthropods
From most to least, order them in the most susceptible order.
Role of 1080 in NZ
- Main weapon against possums, rats, stoats.
- Knock down pesticide, rapidly reducing pest populations to low levels.
- kills in hours (rats) to days (larger mammals)
- Poisoned animals are affected noticeable within few hours
(Causes bait shyness in survivors)
-Not an eradication pesticide, because of bait shyness.
(Best ones are already killing the host before it even realises it, slow acting)
How 1080 is applied?
-Cereal or carrot baits with cinnamon as lure
(deer repellent sometimes added)
- Bait stations
- Hand broadcast
- Aerial drops enable extensive application in remote and/or rugged areas
- Pre-feeding used aerial drops, to persuade pests that baits are safe to eat.
(Then hit them with poisoned baits)
Main way of secondary poisoning?
Scavenging
Timing of control is crucial…
-Minimise ammount (budget),
-maximise effect on target
-minimise affect on important fuana
- Do not drop in Autumn as by the next breeding season rats will have recovered completely & possums slowly.
- Better to drop in spring at start of breeding season, so you can knock the populations down before you need to.
Effects of 1080 on non target species
(foodweb showing how 1080 gets into the food web from aerial application)
- Most common way for it to travel up the food chain is by scavenging, not by predation of animals still alive.
- Food web different to bait station 1080, much more control about where 1080 is going as only certain animals can get into bait stations as not freely available on forest floor.
- Secondary poisoning of rats: rats go in and get 1080 which then get eaten by mustelids and ferrel cats.
By-kill of birds
(1966 robins)
- Aerial application of 1080 in carrot baits to control possums resulted in death of 43% of territorial adult robins.
- tissue analysis confirmed 1080 poisoning
- linked to poor quality of baits
1997
- repeat operation with better quality baits (fewer fragments)
- reduced robin mortality to 9%
Does pre-feeding increase mortality of bbirds as well as that of target species, is it a big contributer to by kill?
- More research on pre-feeding needed
- review of 48 studies showed birds mortality from aerial 1080 drops is generally low (<5%)
- but most of these drops done before pre-feeding became the norm
By-kill of deer from aerial 1080
Dropping 1080 in a forest without deer repellent will kill 50% off deer population in forest.
(unsure why, could be down to size of deer and its resistance to 1080)
How do you work out how many non-target animals have been killed?
- Count dead deer (or whatever animal of concern)
- but how do you know you’ve found them all
- Team goes through forest at right angles to see how many deers found.
- multiply result x3 and thats your total answer?
No known antidote to 1080
- Hospital do forced ventelation as it keeps you breathing until 1080 is metaolised.
- 1080 broken down very quick by soil microbes
- Non persisant in tissues of living animals with sub lethal poisoning so rarely transmitted up the food chain by predation
(if possum ingests and survives, it will be clear of 1080 within 24h)
-Significant secondary poison by scavenging
Pindone
- First-generation anti-coagulant, still widely used in NZ
- Effective against rats
- Not effective against possums (need to eat alot)
- No license needed to use pindone in bait stations.
- Need a license to broadcast by hand or aerial.
‘Humaneness’
Good nature traps
- 70cm above ground
- must lure possum in with bread crumbs on the floor and going up the tree for (cinnamon marmelade)
- Powered y CO2 cannister thats lasts up to 11 shots - or six months
- Need to replace lure/rebait (must visit often)
- scavengers take away carcas away sometimes
- expensive.
