negative impacts of feral hogs - clemson university
TRANSCRIPT
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Biology & Negative Impacts of Feral Hogs
Greg YarrowProfessor of Wildlife Ecology
Clemson University
Beaver & Feral Hog Management Workshop
March 30, 2011
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Wild Hogs - HistoryScientific Pedigree
Wild Hog (or Pig or Swine)
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Wild Hogs - HistoryScientific Pedigree
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Wild Hogs - HistoryHistory in the Southeast
• Wild hogs have a long history in the Southeast
• Populations date back to the mid 1500s
• Derived from domestic swine that went wild (i.e., becoming feral hogs)
• Feral hogs were widespread in the Southeast by the early 1900s
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Wild Hogs - HistoryHistory in the Southeast• Pure Eurasian wild boar introduced into NC in 1912
• Fenced hunting preserve on Hooper Bald
• Animals escaped enclosure • Hybridized with feral hogs in surrounding area
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Wild Hogs - HistoryHistory in the Southeast• In 1900, only three of the states in the SE did not have wild hogs
• By the 1970s, all states in SE had wild hogs
• Recent expansion seen in most states in SE
OK
WVAR
TX
LA
MSAL
SC
VA
NC
FLGA
KYTN
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Wild Hogs - EcologySize, Shape and Color
• Males are larger and heavier than females
• Average adult weights:• Males – 200 lbs.
• Females – 175 lbs.
• Born at <2 pounds
• 30 inches at shoulder
• Total length is 5 to 6 feet
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Wild Hogs - Ecology Size, Shape and Color
“Half-Ton Hog Phenomenon”
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Wild Hogs - Ecology Size, Shape and Color
• Coat coloration is highly variable (e.g., solid, spotted, belted, etc.
• Most variation is due to the mixed ancestry of these animals (feral hog crossed with wild boar)
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Wild Hogs - Ecology Food Habits/Diet• Wild pigs are classified as
opportunistic omnivores• “If it has a calorie in it, and
they can get their mouth around it, wild pigs will eat it”
• Typical composition of diet:• 88% plant matter• 10% animal matter • 2% fungi• <1% misc. (e.g., soil, rocks, sticks, garbage)
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Wild Hogs - Ecology Habitat Requirements• Adaptable to a wide variety of habitats
• Need year‐round access to: • Food and water• Shade• Escape cover
• Recent increase of numbers in urban habitats
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Wild Hogs - Ecology Reproduction
• Very high reproductive potential
• Early sexual maturity (3‐6 months of age)
• Large litters
• Average of 6
• Maximum of 16
• Breed year‐round
• Multiple litters per year
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Wild Hogs - Ecology Social Unit Organization• Basic unit ‐maternal or family group (i.e., sow with her litter of piglets)
• Mature males solitary
• Multiple family groups of related sows as pigs get close to being weaned
• Large groups (100+ animals) can occur around a localized attraction or resource
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Wild Hogs - Ecology Home Range
• Exhibit a “home range” behavior
• Average of 4 sq. mi.
• Maximum of 50 sq. mi.
• Varies depending on spatial availability of food, water, shade and escape cover
• Home range composition:• Core areas
• Network of paths
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Wild Hogs - Ecology Daily Activity Pattern
• Difficult to regard them as either diurnal or nocturnal
• Varies by location• Intense hunting pressure and human activity will drive them to be nocturnal
• Seasonal variation
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Wild Hogs - Ecology Movement Pattern• Drifting or wandering movement pattern
• Move in relation to supporting resources
• Disturbance will cause them to move
• Capable of long‐range movement over the short‐term (up to 200 miles)
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Wild Hogs - Ecology MobilityWild pigs can:
• Run up to 30 mph
• Jump a 3‐ft fence
• Swim across 2 miles of open water
• Turn sharp corners while running
• Ascend very steep inclines
• Jump/climb over 5‐6’ corral trap walls
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Wild Hogs - Ecology Senses
• Smell ‐ Excellent• 5‐7 miles over surface• 25 feet below grade
• Sight ‐ Good• Field of vision is 260 to 275 degrees
• Some binocular vision• “See” threat over 1 mile away
• Hearing ‐ Fair• Highest role in thick cover
• Unknown sounds or noise may cause pigs to go into a “freeze” or alert posture
• “Touch” (Taste)• Done with the mouth• “Mouth” objects to evaluate them
The Nose Knows!
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Wild Hogs - EcologyWild Pig Tracks• Typical cloven‐hoofed print
• Resembles a rounded “W”
• Lateral or dewclaw prints often present
• Deer tracks – toe print are pointed
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Wild Hogs - EcologyWallowing and Rubs• Wallow to cool themselves
• Can be almost any wet depression
• Use rubs for comfort and mud removal
• Rubs are not always associated with wallows
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Wild Hogs - EcologyNests and Beds• Build two types of unique structures: • Farrowing nests
• Resting or loafing beds
• Somewhat similar in appearance
• Can be simple to very complex
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Wild Hogs - EcologyAggressive Behavior• Wild pigs can be very aggressive
• Typically when cornered or threatened
• 5‐10 people killed annually due to wild pig attacks
• Do not “like” dogs
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Negative Impacts of Wild Hogs
• Ecological Damage
• Economic Losses– Agriculture Damage
– Livestock Depredation
– Reforestation Failure
– Damage in Suburban Communities
• Disease Threats Photo Credit: Chris Jaworowski in West et al. (2009)Managing Wild Pigs: A Technical Guide
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Ecological Damage
• Impact of Rooting
• Damage to plant & animal communities
• Increase in exotic plants
• Increase in soil erosion
• Decreased water quality
• Affects on other wildlifePhoto Credit: Chris Jaworowski inWest et al. (2009)Managing Wild Pigs: A Technical Guide
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Ecological Damage
• Impact of rooting
• Besides man, greatest vertebrate modifier of natural communities
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Ecological Damage• Damage to Native Plant Communities
• Direct & indirect effects
• Rooting, trampling, soil compaction, water infiltration
• Disruption of nutrient cycle• Effects most pronounced in wetland areas• Documented declines in NP communities in FL & HI
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Ecological Damage• Damage to Sensitive Plant & Animal Species
• Destruction of rare & endangered plant communities in SC Heritage Preserves
• Depredation to threatened loggerhead sea turtle nests on North Island, Winyah Bay, SC
• FL endangered turtles nests destroyed
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Ecological Damage
• Increase in Exotic & Less Desirable Plants
• Frequent rooting disturbance favors competitive non‐native plants
• Out compete native plants
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Ecological Damage
• Increase in Soil Erosion
• Loss of soil fertility, plant growth, plant diversity
• Effects on water quality from siltation
Photo Credit:Eddie Parham in West et al. (2009)Managing Wild Pigs: A Technical Guide
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Ecological Damage• Decreased Water Quality
• Soil runoff & bacterial contamination
• Impacts aquatic flora & fauna
• Freshwater mussels & insects impacted
• Fecal coliforms in some streams exceeds human health standards
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Ecological Damage
• Effects on Other Wildlife
• Damage to habitat
• Direct predation
• Significant predators of ground nesting bird nests
• Competition for resources, especially soft & hard mast (fruit)
• Spread of diseases & parasites
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Economic Losses• Agricultural Damage
• $ 1.5 billion lost annually in U.S.
• Consume & trample crops, damage pastures by rooting & digging
• Hay, small grains, corn, peanuts, vegetables, watermelons, soybeans, cotton, tree fruits & others
• Damage to fences, roads, dikes
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Economic Losses
• Livestock Depredation
• Prey on lambs, goats, newborn cattle, poultry, & exotic game
• Predation on young animals usually occurs on calving or lambing grounds, may be attracted to afterbirth
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Pattern of Wild Pig Predation• Difficult to verify, entire carcass is usually consumed, leaving little evidence.
• Also scavenge carcasses killed by other animals.
• Kill prey by biting & crushing skull or neck; carcass skinned & stomach contents consumed.
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Economic Losses• Forestry/Reforestation Challenges
• Regeneration of hardwoods from seed may be difficult
• Hardwood & pine seedlings (especially longleaf) are very susceptible to pig damage through consumption, rooting, & trampling
Photo Credit: Steve Gulledge inWest et al. (2009)Managing Wild Pigs: A Technical Guide
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Economic Losses
• Damage in Suburban Communities
• Yard, landscape & ornamental plant damage
• Garden damage
• Golf course damage
Photo Credit: Billy Higginbotham inWest et al. (2009)Managing Wild Pigs: A Technical Guide
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Economic Losses
• Management for Game Species
• Destruction of wildlife plantings & food plots
• Consumption of corn & other supplemental foods at feeders
• Damage to habitats Photo Credit: Chris Jaworowski inWest et al. (2009)Managing Wild Pigs: A Technical Guide
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Disease Threats• Carry disease that affect humans, livestock, & wildlife
• Humans ‐ brucellosis, leptospirosis, salmonellosis, toxoplasmosis, sarcoptic mange, E. coli, & trichinosis
• Livestock & Wildlife ‐pseudorabies, swine brucellosis, tuberculosis, vesicular stomatis, & classical swine fever
• Serve as a reservoirs & amplifier for other diseases (e.g. foot & mouth disease)
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Positive Impacts of Wild Hogs ?
• Increased hunting opportunities
• Increase revenue from hunts
• Rooting may stimulate production of native plants that require disturbance
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Wild Hog Efforts in SCChange in regulation last year
2 past research projects (Congaree NP)
Two workshops in August 2009
Other workshops scheduled• March 30th in Lexington, SC
• May 12th Brosnan Forest
• June 9th, Sandhills REC
Cost‐sharing in 2 counties by Conservation Districts
Formation of SC Wild Hog Task Force
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Questions ?