Wildlife Control Flashcards
Reasons for pest control
- damage agricultural and horticultural crops
- forestry dmage
- ecosystems
- competition with livestock for feed
- risk of predation of livestock and farmed fish
- risk predation of endangerered wildlife
- risk of transmission of speicifc diseases to livestock
- risk of zoonotic diseases spreading to man
- property damage
- consumption and contamination of stored feedstuffs
- risk of overpopulation and emaciation of the species (eg. flamethrowers mice!)
egs. pers control for animal dz control
- m bovis and brushtail possums (New Zealand)
- m bovis and badgers
- maintainance hosts and spill over hosts
Maintainance or spillover hosts most important for disease control?
> maintainance
- spillover only important if levels in maintainance hosts so high above threshold then control both
egs of zoonoses transmitted by wildlife?
> aveolar hydatid disease (e. multilocularis) - urban foxes > haemorrhagic fever with renal syndrome (hanta virus) - rats > leptospira - rats > bird flu (avian influenza A H5N1) - wild waterfowl > toxoplasmosis (toxoplasma gondii) - feral cats > lassa fever (arenaviridae) - mice
3 componenets of approach to wildlife control programme
- set clearly defined objectives
- decide how to achieve
- monitor outcome of plan
> goals should be transparent and defensible when when outcomes are uncertain
2 main control strategies
> damage control - deterrents - exclusion > pest control - sustained destruction - eradication
eg. repellent, deterrant and ecclusion devices
- noise emitters (bird scarer, u/s alarm)
- visual scarers (scarecrow)
- chemical repellents (copper acetate to repel sharks)
- habitat removal (roost removal around fruit farms)
- eclusion (electric fencing, vermin proof dororways)
- feed competition (encouraging competitiors less of a pest)
potential impacts of wildlife control
- removing predators reshuffles food chain
- increased growth of other predators etc.
egs of pest control methods
- toxicants
- traps and snares
- introducing disease
- inctroducing predators
- hunting/shooting/fishing
> bounties
> recreational hunting (does have an impact)
Monitoring outcomes of wildlife control
- kill rates
- elimination rate (proportion removed in a given period, need to know how many badgers were in the envinroment initially)
- impact rate (improvement in resource, change in pest density etc)
> measured by - catch rates
- scant density
- feed removal/activity at bait stations
- head counts/plot occupancy
- renway/borrowing opening counts
- impact assessment (looking at incidence of disease, regrowth of trees etc.)
define welfare compromise equation
W = N*I*D*C w=welfare n= no animals I=intensity d= duration c= capacity of the animals to suffer
eg UK LEGAL toxicants
> alpha chloraslose
- only works very small aniamsl mice and shrews
- developed as an anaesthetic (causes hypothermia)
anticoagulants (vit K antagonist)
- 1st gen (warfarin)
2nd gen ( brodifacoum etc.)
Is potassium cynanide a good toxicant?
- very humane
- acute acting toxin
- fast acting
- NOT LEGAL UK (human health risk)
- but rodents often will not consume full lethal dose -> bait shyness d/t sickness
How do acute and cumulative toxicants differ
- acute more welfare friendly IF consume lethal dose
- cumulative don’t associate food with sickness 3-4d cumulation but then 4d suffering from haemorrhage esp into joints
concerns of ingested toxins
> mode of action - intesntiy and duration suffering > non-target poisoning - wrong species eats it > 2* poisoning - eating carcasses - predators often have high levels -> delayed onset decrease in population > sub lethal poisoning
