Luke
29-07-06, 10:31 AM
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-pigbanner.jpg
Feral Pigs in Queensland
Distribution, ecology and impact.
Domestic pigs (Sus scrofa) were introduced to Australia by early settlers. Subsequent accidental and deliberate releases resulted in the wild (feral) population establishing throughout Queensland. Feral pigs damage crops, stock and property, spread weeds and transmit disease such as Leptospirosis and foot and Mouth. They can also cause environmental damage digging up large areas in national parks, and spreading weeds.
Land Managers are legally obliged to control feral pigs in Queensland under the Rural Lands Protection Act.
For information on control of feral pigs see DNR Pest Facts PA7. for specific information on feral pig management in the wet tropics, see DNR Pest Fact PA8.
Description.
Australian feral pigs have more in common with their Eurasian cousins than with domestic pigs. They are smaller, leaner, and more muscular than domestic pigs, with well-developed shoulders and necks and smaller, shorter hindquarters. their hair is sparse and longer and coarser than domestic pigs. Feral pigs can also have longer, larger snouts and tusks, straight tails, smaller mostly pricked ears and much narrower backs.
Colouring is predominantly black, buff-coloured or spotted black and white. Some are agouti-patterned (dark hair with lighter tip). Juveniles may be striped. Colours vary between and within areas.
Growth potential is similar to domestic pigs, though harsh environmental conditions tend to stunt development. The weight if an average adult female feral pig is roughly 50 to 60kg, with the males usually weighing 80 to 100kg. Exceptional animals have reached 260kg.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-adampigblack.jpg
Old boars (razorbacks) have massive heads and shoulders and a raised and prominent back bone which slopes steeply down to small hams and short hind legs. A keratinous plaque or shield up to three centimeters which usually develops on their shoulders and flanks. this provides some protection from serious injury during fights with other boars.
Some boars develop a crest or mane of stiff bristles extending from their neck down the middle of their back, which stands straight in end when the animal is enraged.
Distribution.
Feral pigs inhabit about 40% of Australia from subalpine grasslands to monsoonal floodplains and are found in all habitat types in Queensland – see figure 1.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-pigdistrib.jpg
Areas need only supply the basis of food, water and cover.
Estimations of number range up to 24 million. the greatest concentrations of feral pigs in on the larger drainage basins and swamp areas of the coast and inland.
Biology and behaviour.
Feral pigs are capable of migrating considerable distances but they tend to stay in home ranges, with watering points the focus of activity, particularly during hot weather. Pigs have few sweat glands, so high temperatures require them to drink more often and wallow in water or mud to cool off. Dense cover is the preferred habitat, providing protection from the sun and their main predator – man.
Female and juvenile pigs usually live in small family groups with a home range of 2 – 20km². Adult males are typically solitary, with a home range of 8 – 50km². Range size varies with season, habitat, food availability and disturbance. Herds of 400 pigs have been recorded ion Cape York.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-adampig.jpg
Most pigs remain in their home range, even when subject to some disturbance such as infrequent hunting by people and dogs. Regular disturbance will drive them on.
Feral pigs are generally nocturnal, spending daylight hours sheltering in dense cover. They are shy animals and will avoid humans, making it easy to miss their presence of to drastically underestimate their numbers.
Pigs are omnivorous, eating both plants and animal flesh. They are extremely opportunistic feeders, exploiting any temporarily abundant food. They prefer green feed, and will eat grains, sugar cane and other crops, fruits and vegetables. They root extensively for tubers, worms and soil invertebrates. Small animals are preyed upon. Stock losses occur primarily with lambs but occasionally with newborn calves. Carrion (dead and rotting flesh) is also consumed.
Feral pigs have relatively high energy and protein requirements, particularly during pregnancy and lactation. These requirements are not available for all the year in all areas, so pigs often have to move to other parts of their home range during pregnancy.
This seasonal need for either more food, of high energy or protein-rich food, is often the reason for their impact on agricultural crop. It is also the weakness in their ecology that can be exploited for management purposes.
Life Cycle.
The reproductive potential of feral pigs is more similar to rabbits than other large mammals in Australia. in good conditions feral pig’s populations may increase five fold in a twelve-month period.
Under favourable conditions breeding occurs all year. Adult female have a 21 day oestrus cycle, with a gestation period of about 113 days, producing a little of four to ten piglets, depending on the sow’s age, weight and food supply.
Sows can make nests of available vegetation just before farrowing. Nests can be 3m long by 1.5m wide and up to 1m high, with a domed roof. They are usually less than 2km from available water. Piglets normally spend the first 1 – 5 days of life inside the nest, with the sow inside of close by.
The next fertile mating can occur after 2 – 3 months of the farrowing, allowing sows to produce two litters per year if good seasonal conditions prevail.
Weaning occurs after 2 to 3 months. Sexual maturity us reached when sows weigh about 25kg, usually around 6 months of age.
Mortality of juveniles is high if the mother’s dietary protein intake is low (up to 100% mortality in dry seasons). Adult mortality does not vary as much with seasonal conditions, bur few animals live more than 5 years.
Estimating populations.
sightings are the least reliable guide to feral pig presence. Careful observation of the signs of pig activity will allow an experienced observer to estimate population densities. A beginner however may see nothing.
The following is a list of common pig signs that may be used to establish relative numbers and sizes.
fresh digging or rooting of ground (caused a ploughed appearance) indicates recently pig activity but area affected gives little indication of numbers as large areas can be dug by a small number of pigs
tracks and faeces on and off pads. Faeces size, shape and consistency varies with age and diet, but is typically 3 – 6 cm wide, 7 – 22cm long and well formed. Close inspection can enable diet to be established – plant matter and seeds, eggshell and bone fragment, wool, and marsupial hair.
◊ mud or hair at holes in fences where pigs have pushed through
◊ wallows – distinctive oval depressions in mud
◊ Tusk marking and mud rubs on trees and fence posts give an indication pig
size
◊ Nests in vegetation made by sows before farrowing; should only be approached with caution.
◊ Spotlight, aerial survey, and use of dogs can be used for actual pig counts.
Impact on man and the environment.
Feral pigs’ wide habitat range, omnivorous diet and potential for rapid population growth in good seasons means few agricultural pursuits are unaffected. Damage is estimated at 80 million dollars annually.
Economic impact is of three types:
Value of the direct losses to agricultural production
Value of the continuing expenditure on pig control
Value of lost opportunities to take profit from alternative investment of this expenditure.
Examples of direct agricultural losses:
Crops.
Pigs can damage almost all crops from sowing to harvest, starting with uprooting seed and seedlings to feeding on or trampling mature crop.
They feed on seed and grain crops (except sunflower), fruit (especially banana, mango, pawpaw, macadamia and lychee) and vegetable crops.
Most damage to sugar cane occurs during the dry season. Older cane with a high sugar content is preferred. Pigs can ‘camp’ in a paddock for several weeks, causing substantial damage, as sufficient moisture can be obtained from the cane.
Livestock
Predation on livestock is basically limited to the taking of lambs. Research has shown feral pigs can take as many as 40% of lambs. This not only reduces income from the sale of lambs, but also reduces the opportunity for herd improvement by limiting selection for optimum wool traits.
Pasture
Pastures are damaged by grazing and rooting. Pigs can also transport weeds, and their diggings provide ideal conditions for weed establishment.
Fence and watering points
Wallowing pigs damage and foul the water in tanks and bore drains, and silt up troughs. Rooting can weaken dam walls. Being large powerful animals, pigs can breach fences, allowing passage of other pest animals.
Environmental concerns
Pig activity has a dramatic affect on creeks and lakes. In many areas concentrated rooting ‘ploughs’ up to 20 m around the waterline.
Such disturbance of the natural vegetation affects not only water quality but the habitat for small animals of both the land and water. It also creates erosion and allows the establishment of exotic weeds.
Predation of native fauna does occur as examination of faeces has shown remains of marsupials, reptiles and insect, ground nesting birds and their eggs, and native flora.
Disease and parasites
Feral pigs can carry many infectious diseases and internal and external parasites. Some are endemic (already present) while others are still exotic to Australia.
Many of the diseases can not only spread to domestic pigs but to other livestock and humans. Diseases naturally transmitted from animal to man are called Zoonoses.
Zoonoses currently in feral pigs in Australia:
Tuberculosis (TB) – A serious disease of the lungs. Once common but now rare, contracted by eating inadequately cooked flesh of infected animals.
Brucellosis, Porcine and Bovine – A bacterial disease causing severe long-term illness, undulant fever and possible infertility, both strains are contracted by handling raw meat. Porcine Brucellosis is rare in Queensland.
Feral pigs were blamed for the spread of both TB and Bovein Brucellosis amongst cattle but both diseases have been eradicated from Queensland without directly targeting feral pigs.
Sparganosis – a parasite that can infest the muscles of humans forming encyst lumps, is common is pigs from swampy areas, contracted by ingesting raw meat.
Melioidosis - a serious bacterial disease which causes abscesses.
Leptospirosis – a serious bacterial disease; in humans call Weil’s disease, causing very high temperatures, kidney troubles and jaundice; can be fatal. It is found in up to 20% of feral pigs in Queensland.
Q Fever – this disease occurs in all animals and is well known by meat workers. It can cause very high temperatures and result in heart problems, can be fatal.
Leptospirosis and Q Fever infection can occur through contact with blood, meat and urine through broken skin, intake if urine contaminated food or water, and inhalation of infectious air-borne organisms.
Brucellosis, Leptospirosis and Q Fever can cause flu-like symptoms similar to Ross River Fever and both Lepto and Q Fever can be fatal.
Owing to these diseases it is advisable to avoid handling feral pigs unless they are slaughtered at a licensed premises where there is a full time meat inspector on duty to ensure that animals are free of the above diseases.
If you must handle feral pig meat use suitable protective clothing (mask, goggles, strong rubber gloves and plastic apron and boots) to minimise contamination with blood, urine and faeces.
Normal thorough cooking destroys al of the pathogens described above, so infection by eating infected meat is not as big risk as when butchering the animal.
Exotic Livestock diseases
A major concern with feral pigs is its potential to harbour or spread exotic diseases. The cost to the Australian community if Foot and Mouth Disease was introduced to Australia is estimated at $3 billion in lost export trade, even if the outbreak was eradicated immediately. This would result in major social upheaval in rural Australia.
Other exotic diseases of concern:
Swine vascular disease – viral disease only affecting pigs
Aujeszky’s disease – highly contagious herpes viral disease affecting several animal species, killing up to 100% of affected piglets.
African Swine Fever – highly contagious viral disease affecting only piglets, mortality rate high.
Classical Swine Fever (CSF) – or hog cholera, highly contagious viral disease of pigs, in acute form killing up to 90% of infected animals.
For more information on animal diseases contact your local DPI veterinarian.
Exotic zoonitic diseases and parasites
Japanese encephalitis – a virus spread from pigs to humans by mosquitoes, causing acute severe problems of the nervous system ie. pain, sleepiness, and coma.
Rabies – a serious disease affecting the brain, can be fatal.
Screw-worm fly – a fly whose maggots can attack healthy flesh and if untreated can cause massive wounds to animals and humans.
Trichinosis – is a helminth (roundworm). All mammals are susceptible, with humans infected by eating improperly cooked meat.
North Queensland’s popularity as a tourist destination is increasing. Many international visitors have travelled through countries infected with exotic diseases before entering Australia. Feral pigs are known to frequent rubbish bins tips around tourist lodges and to scavenge human waste.
There is a real danger that an exotic disease could enter Australia via this contact and remain undetected for some time. Such time lapse could allow the disease to become widespread, making eradication difficult or even impossible.
Feral Pigs in Queensland
Distribution, ecology and impact.
Domestic pigs (Sus scrofa) were introduced to Australia by early settlers. Subsequent accidental and deliberate releases resulted in the wild (feral) population establishing throughout Queensland. Feral pigs damage crops, stock and property, spread weeds and transmit disease such as Leptospirosis and foot and Mouth. They can also cause environmental damage digging up large areas in national parks, and spreading weeds.
Land Managers are legally obliged to control feral pigs in Queensland under the Rural Lands Protection Act.
For information on control of feral pigs see DNR Pest Facts PA7. for specific information on feral pig management in the wet tropics, see DNR Pest Fact PA8.
Description.
Australian feral pigs have more in common with their Eurasian cousins than with domestic pigs. They are smaller, leaner, and more muscular than domestic pigs, with well-developed shoulders and necks and smaller, shorter hindquarters. their hair is sparse and longer and coarser than domestic pigs. Feral pigs can also have longer, larger snouts and tusks, straight tails, smaller mostly pricked ears and much narrower backs.
Colouring is predominantly black, buff-coloured or spotted black and white. Some are agouti-patterned (dark hair with lighter tip). Juveniles may be striped. Colours vary between and within areas.
Growth potential is similar to domestic pigs, though harsh environmental conditions tend to stunt development. The weight if an average adult female feral pig is roughly 50 to 60kg, with the males usually weighing 80 to 100kg. Exceptional animals have reached 260kg.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-adampigblack.jpg
Old boars (razorbacks) have massive heads and shoulders and a raised and prominent back bone which slopes steeply down to small hams and short hind legs. A keratinous plaque or shield up to three centimeters which usually develops on their shoulders and flanks. this provides some protection from serious injury during fights with other boars.
Some boars develop a crest or mane of stiff bristles extending from their neck down the middle of their back, which stands straight in end when the animal is enraged.
Distribution.
Feral pigs inhabit about 40% of Australia from subalpine grasslands to monsoonal floodplains and are found in all habitat types in Queensland – see figure 1.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-pigdistrib.jpg
Areas need only supply the basis of food, water and cover.
Estimations of number range up to 24 million. the greatest concentrations of feral pigs in on the larger drainage basins and swamp areas of the coast and inland.
Biology and behaviour.
Feral pigs are capable of migrating considerable distances but they tend to stay in home ranges, with watering points the focus of activity, particularly during hot weather. Pigs have few sweat glands, so high temperatures require them to drink more often and wallow in water or mud to cool off. Dense cover is the preferred habitat, providing protection from the sun and their main predator – man.
Female and juvenile pigs usually live in small family groups with a home range of 2 – 20km². Adult males are typically solitary, with a home range of 8 – 50km². Range size varies with season, habitat, food availability and disturbance. Herds of 400 pigs have been recorded ion Cape York.
http://i89.photobucket.com/albums/k205/griffo79/ferfiles-adampig.jpg
Most pigs remain in their home range, even when subject to some disturbance such as infrequent hunting by people and dogs. Regular disturbance will drive them on.
Feral pigs are generally nocturnal, spending daylight hours sheltering in dense cover. They are shy animals and will avoid humans, making it easy to miss their presence of to drastically underestimate their numbers.
Pigs are omnivorous, eating both plants and animal flesh. They are extremely opportunistic feeders, exploiting any temporarily abundant food. They prefer green feed, and will eat grains, sugar cane and other crops, fruits and vegetables. They root extensively for tubers, worms and soil invertebrates. Small animals are preyed upon. Stock losses occur primarily with lambs but occasionally with newborn calves. Carrion (dead and rotting flesh) is also consumed.
Feral pigs have relatively high energy and protein requirements, particularly during pregnancy and lactation. These requirements are not available for all the year in all areas, so pigs often have to move to other parts of their home range during pregnancy.
This seasonal need for either more food, of high energy or protein-rich food, is often the reason for their impact on agricultural crop. It is also the weakness in their ecology that can be exploited for management purposes.
Life Cycle.
The reproductive potential of feral pigs is more similar to rabbits than other large mammals in Australia. in good conditions feral pig’s populations may increase five fold in a twelve-month period.
Under favourable conditions breeding occurs all year. Adult female have a 21 day oestrus cycle, with a gestation period of about 113 days, producing a little of four to ten piglets, depending on the sow’s age, weight and food supply.
Sows can make nests of available vegetation just before farrowing. Nests can be 3m long by 1.5m wide and up to 1m high, with a domed roof. They are usually less than 2km from available water. Piglets normally spend the first 1 – 5 days of life inside the nest, with the sow inside of close by.
The next fertile mating can occur after 2 – 3 months of the farrowing, allowing sows to produce two litters per year if good seasonal conditions prevail.
Weaning occurs after 2 to 3 months. Sexual maturity us reached when sows weigh about 25kg, usually around 6 months of age.
Mortality of juveniles is high if the mother’s dietary protein intake is low (up to 100% mortality in dry seasons). Adult mortality does not vary as much with seasonal conditions, bur few animals live more than 5 years.
Estimating populations.
sightings are the least reliable guide to feral pig presence. Careful observation of the signs of pig activity will allow an experienced observer to estimate population densities. A beginner however may see nothing.
The following is a list of common pig signs that may be used to establish relative numbers and sizes.
fresh digging or rooting of ground (caused a ploughed appearance) indicates recently pig activity but area affected gives little indication of numbers as large areas can be dug by a small number of pigs
tracks and faeces on and off pads. Faeces size, shape and consistency varies with age and diet, but is typically 3 – 6 cm wide, 7 – 22cm long and well formed. Close inspection can enable diet to be established – plant matter and seeds, eggshell and bone fragment, wool, and marsupial hair.
◊ mud or hair at holes in fences where pigs have pushed through
◊ wallows – distinctive oval depressions in mud
◊ Tusk marking and mud rubs on trees and fence posts give an indication pig
size
◊ Nests in vegetation made by sows before farrowing; should only be approached with caution.
◊ Spotlight, aerial survey, and use of dogs can be used for actual pig counts.
Impact on man and the environment.
Feral pigs’ wide habitat range, omnivorous diet and potential for rapid population growth in good seasons means few agricultural pursuits are unaffected. Damage is estimated at 80 million dollars annually.
Economic impact is of three types:
Value of the direct losses to agricultural production
Value of the continuing expenditure on pig control
Value of lost opportunities to take profit from alternative investment of this expenditure.
Examples of direct agricultural losses:
Crops.
Pigs can damage almost all crops from sowing to harvest, starting with uprooting seed and seedlings to feeding on or trampling mature crop.
They feed on seed and grain crops (except sunflower), fruit (especially banana, mango, pawpaw, macadamia and lychee) and vegetable crops.
Most damage to sugar cane occurs during the dry season. Older cane with a high sugar content is preferred. Pigs can ‘camp’ in a paddock for several weeks, causing substantial damage, as sufficient moisture can be obtained from the cane.
Livestock
Predation on livestock is basically limited to the taking of lambs. Research has shown feral pigs can take as many as 40% of lambs. This not only reduces income from the sale of lambs, but also reduces the opportunity for herd improvement by limiting selection for optimum wool traits.
Pasture
Pastures are damaged by grazing and rooting. Pigs can also transport weeds, and their diggings provide ideal conditions for weed establishment.
Fence and watering points
Wallowing pigs damage and foul the water in tanks and bore drains, and silt up troughs. Rooting can weaken dam walls. Being large powerful animals, pigs can breach fences, allowing passage of other pest animals.
Environmental concerns
Pig activity has a dramatic affect on creeks and lakes. In many areas concentrated rooting ‘ploughs’ up to 20 m around the waterline.
Such disturbance of the natural vegetation affects not only water quality but the habitat for small animals of both the land and water. It also creates erosion and allows the establishment of exotic weeds.
Predation of native fauna does occur as examination of faeces has shown remains of marsupials, reptiles and insect, ground nesting birds and their eggs, and native flora.
Disease and parasites
Feral pigs can carry many infectious diseases and internal and external parasites. Some are endemic (already present) while others are still exotic to Australia.
Many of the diseases can not only spread to domestic pigs but to other livestock and humans. Diseases naturally transmitted from animal to man are called Zoonoses.
Zoonoses currently in feral pigs in Australia:
Tuberculosis (TB) – A serious disease of the lungs. Once common but now rare, contracted by eating inadequately cooked flesh of infected animals.
Brucellosis, Porcine and Bovine – A bacterial disease causing severe long-term illness, undulant fever and possible infertility, both strains are contracted by handling raw meat. Porcine Brucellosis is rare in Queensland.
Feral pigs were blamed for the spread of both TB and Bovein Brucellosis amongst cattle but both diseases have been eradicated from Queensland without directly targeting feral pigs.
Sparganosis – a parasite that can infest the muscles of humans forming encyst lumps, is common is pigs from swampy areas, contracted by ingesting raw meat.
Melioidosis - a serious bacterial disease which causes abscesses.
Leptospirosis – a serious bacterial disease; in humans call Weil’s disease, causing very high temperatures, kidney troubles and jaundice; can be fatal. It is found in up to 20% of feral pigs in Queensland.
Q Fever – this disease occurs in all animals and is well known by meat workers. It can cause very high temperatures and result in heart problems, can be fatal.
Leptospirosis and Q Fever infection can occur through contact with blood, meat and urine through broken skin, intake if urine contaminated food or water, and inhalation of infectious air-borne organisms.
Brucellosis, Leptospirosis and Q Fever can cause flu-like symptoms similar to Ross River Fever and both Lepto and Q Fever can be fatal.
Owing to these diseases it is advisable to avoid handling feral pigs unless they are slaughtered at a licensed premises where there is a full time meat inspector on duty to ensure that animals are free of the above diseases.
If you must handle feral pig meat use suitable protective clothing (mask, goggles, strong rubber gloves and plastic apron and boots) to minimise contamination with blood, urine and faeces.
Normal thorough cooking destroys al of the pathogens described above, so infection by eating infected meat is not as big risk as when butchering the animal.
Exotic Livestock diseases
A major concern with feral pigs is its potential to harbour or spread exotic diseases. The cost to the Australian community if Foot and Mouth Disease was introduced to Australia is estimated at $3 billion in lost export trade, even if the outbreak was eradicated immediately. This would result in major social upheaval in rural Australia.
Other exotic diseases of concern:
Swine vascular disease – viral disease only affecting pigs
Aujeszky’s disease – highly contagious herpes viral disease affecting several animal species, killing up to 100% of affected piglets.
African Swine Fever – highly contagious viral disease affecting only piglets, mortality rate high.
Classical Swine Fever (CSF) – or hog cholera, highly contagious viral disease of pigs, in acute form killing up to 90% of infected animals.
For more information on animal diseases contact your local DPI veterinarian.
Exotic zoonitic diseases and parasites
Japanese encephalitis – a virus spread from pigs to humans by mosquitoes, causing acute severe problems of the nervous system ie. pain, sleepiness, and coma.
Rabies – a serious disease affecting the brain, can be fatal.
Screw-worm fly – a fly whose maggots can attack healthy flesh and if untreated can cause massive wounds to animals and humans.
Trichinosis – is a helminth (roundworm). All mammals are susceptible, with humans infected by eating improperly cooked meat.
North Queensland’s popularity as a tourist destination is increasing. Many international visitors have travelled through countries infected with exotic diseases before entering Australia. Feral pigs are known to frequent rubbish bins tips around tourist lodges and to scavenge human waste.
There is a real danger that an exotic disease could enter Australia via this contact and remain undetected for some time. Such time lapse could allow the disease to become widespread, making eradication difficult or even impossible.