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Grizzly bears, black bears, wolves, coyotes, cougars/ mountain lions,bobcats, wolverines, lynx, foxes, fishers and martens are the suite of carnivores that originally inhabited North America after the Pleistocene extinctions. This site invites research, commentary, point/counterpoint on that suite of native animals (predator and prey) that inhabited The Americas circa 1500-at the initial point of European exploration and subsequent colonization. Landscape ecology, journal accounts of explorers and frontiersmen, genetic evaluations of museum animals, peer reviewed 20th and 21st century research on various aspects of our "Wild America" as well as subjective commentary from expert and layman alike. All of the above being revealed and discussed with the underlying goal of one day seeing our Continent rewilded.....Where big enough swaths of open space exist with connective corridors to other large forest, meadow, mountain, valley, prairie, desert and chaparral wildlands.....Thereby enabling all of our historic fauna, including man, to live in a sustainable and healthy environment. - Blogger Rick

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Thursday, March 12, 2015

Can the Feral Hog population be taken down and reduced to negligible numbers by our native carnivores?.........Thirty Nine states are in various stages of "infestation" of this prolific breeding and turf destructing animal, a descendant of Domestic Pigs set free by farmers over the generations dating back to the founding of our Country in the 1600's................ Wild pigs cause at least $1.5 billion in damages and control costs each year according to a 2007 survey, mostly to agriculture............... Dubbed the “rototillers of nature,” they dig up fields, create wallows in pastures and destroy fences.............. Researchers have found that you have to remove at least 70% of a Pig population to begin to push down their numbers and even that success ratio does not ensure that they will be removed entirely from a given region...............Poisoning Pigs using Sodium nitrite is being considered as a solution by Researchers but how to do this without causing death in other livestock and wildlife is at this point problematic at best..................Unfortunately, other than Pumas and potentially Wolves,,,,,, black bears, coyotes, bobcats, lynx, and other of our native carnivore suite are only "opportunistic" hunters of Feral Hogs,,,,,,,,,,,and they usually targeti only the more vulnerable piglets, not the adults..............Shows how exotics from other lands, whether they be animal or plant species, can throw a devastating "monkey wrench" into our natural systems, upending the "biological apple cart" and near permanently destroying biodiversity and important natural systems,d.cWc

Natural Predators of Feral Hogs

Feral hogs (also called wild hog; Sus scrofa) are preyed on by several natural (that is, nonhuman) species of carnivores and omnivores in the United States.  However, man is still unquestionably the primary and most significant predator of non-native feral hogs.  For the most part, predation by natural species is thought to represent only a minor role in the mortality of feral hogs throughout their range.  Further, most of this predation is directed toward the younger age classes within a feral hog population.  The following are species accounts of what is known about the various native and non-native natural predators in the United States that have been either documented or are thought to have the potential to prey on feral hogs. 
American Alligator  The predation of feral hogs by alligators has been well documented in both the scientific and popular literature.  However, alligator predation on this invasive species has been described as being either opportunistic or limited.  Alligators have been known to take a variety of sizes of feral hogs, even being able to catch and kill very large hogs that are swimming across open water.  In fact, the open water capture and drowning of feral hogs is probably the most common manner in which this type of predation occurs.  In other instances, alligator have been observed to rush, catch, and then drown feral hogs that were standing near the water's edge.  The overall impact of alligator predation on a feral hog population would be minimal. 
Turkey Vulture  Primarily a scavenger, this vulture species is also opportunistic in its foraging habits.  In one reported account in an open rangeland area of south Florida, three adult turkey vultures were observed to fly in, surround, and stop a feral piglet's escape with their outstretched wings.  Using stabbing strikes with their beaks, the trio was then able to kill their victim, which they then consumed.  The piglet was small and, by its lethargic behavior, did not appear to be completely healthy.  Given the circumstances, predation of feral hogs by this avian scavenger would be a possible but extremely rare event.
Red-tailed Hawk  Although typically a predator of small birds and mammals, the red-tailed hawk will prey on small feral piglets given the right circumstances.  Observations of this hawk species preying on feral piglets on Ossabaw Island off of the Georgia coast have been reported on three occasions.  The more open habitat found on Ossabaw Island may have enabled the success of these predatory attempts.  In addition, the small size and high percentage of solitary piglets within that feral hog population may account for these multiple observations of this type of predation. 
Golden Eagle  Typically a predator of small mammals taken on the ground, the golden eagle has been documented to opportunistically prey on feral piglets.  This is also true within the Eurasian portion of this raptors' species range.  In general, this type of predation is neither common nor widespread.  However, the presence of a large prey base in the form of feral piglets has been theorized to have caused the establishment of nesting golden eagles on the California Channel Islands.  When the islands’ various feral hog populations were either eradicated or reduced, the then resident golden eagles began to prey on the indigenous island foxes, almost driving this already threatened species to extinction. 
Owls – Owls have been anecdotally reported as predators of small feral hogs and piglets; however, no further details on the species of owl or the associated circumstances were provided in these accounts.  Given its potential to prey on other animals of comparable size, the great horned owl would represent a potential predator of feral piglets in this country.  The Eurasian eagle owl, an Old World species that is closely related the great horned owl, has been documented as a predator of wild piglets. 
Feral Dog  Present in most states, feral dogs represent a known predator of feral hogs in this country.  The predatory impact of feral dog packs would be mostly realized toward piglets andshoats within a feral hog population. 
Coyote  A common native canid that has expanded its range throughout most of the continental United States, the coyote has been documented as preying on feral hogs in a number of locations.  Most coyote predation of feral hogs is directed at younger or smaller animals.  Overall, the predatory impact of coyotes on feral hogs is unknown.  The presence of feral hog remains in coyote stomachs and scats could be the result of either direct predation or carrion scavenging.  Because of an increased presence of these remains during hunting seasons, two studies have suggested that scavenging of carcasses was the primary source of feral hogs in coyote diets. 
Red Wolf  Effectively extinct in the wild, the red wolf has been reintroduced onto Bull's Island, South Carolina, into the Alligator River National Wildlife Refuge (ARNWR), North Carolina, and into the Great Smoky National Park (GSMNP), North Carolina and Tennessee.  Prior to their removal from the wild in the GSMNP, the red wolves there were documented to prey on hogs in the southern portion of the park.  Feral hogs have also recently been found on the ARNWR; however, there have been to date no reports of red wolf predation on these hogs. 
Red Fox – The red fox was reported as a potential predator of very young piglets in eastern Tennessee; however, no specific accounts exist reporting the predation of feral piglets by this fox species in the United States.  However, there are several reported accounts of predation on wild piglets by red fox in both Europe and Asia. 
Gray Fox – Like the red fox, this species has been identified as having the potential to prey on very young feral piglets on occasion.  One study, which looked at gray fox diet in areas with hogs, found the presence of only a small amount of feral hog remains, and that was reportedly the result of scavenging by this small canid.
Black Bear  The black bear is known to prey on feral hogs of all ages; however, the impact of predation by this bear on feral hog populations is not known.  Some researchers have speculated that black bears probably kill few if any feral hogs, especially given that an adult hog would represent a formidable adversary for a black bear.  In fact, in the 1920s a feral boar in the Okefenokee Swamp was reported to have killed a black bear in a fight between the two animals.  Similar accounts of feral boars killing bears during fights in the Ozark Mountains of Arkansas were reported in the 1880s.  Being opportunistic, black bears have been reported to raid nylon net live traps used for feral hog control at high elevations in the GSMNP to obtain any trapped hogs contained within these devices. 
Small Indian Mongoose – This introduced mongoose has been reported to prey on feral piglets in the Hawaiian Islands.  An investigation of mongoose stomach contents on Maui revealed feral hog remains in five of the 18 stomachs analyzed.  However, it was not possible to establish that this was not the result of carrion feeding as opposed to direct predation.  Accounts also exist of this same species of mongoose preying on young free-ranging domestic pigs in Jamaica. 
Bobcat  This small wild cat is found in most areas where introduced feral hog populations exist in this country.  The predation of feral piglets by bobcats has been documented in both scientific and popular accounts.  In the Southeast, bobcats have been reported by some studies as being important predators of young wild piglets.  However, most studies have shown that feral hogs were not a major component of the bobcat diet.
Ocelot – Although neither common nor widespread, this small neotropical cat has been documented to prey on feral hogs in south Texas.  Feral hog remains were found in 21 percent of ocelot scats examined from the Lower Rio Grande Valley.  In addition, ocelots were reported to be fond of young domestic pigs as prey in Texas in the early 1900s. 
Mountain Lion or Cougar  The large cat is found to overlap the range of feral hogs in several western states and in Florida.  In both general regions mountain lions have been documented to prey on introduced feral hogs.  The target animals include both sexes and potentially any age class.  Given the right situation, a mountain lion could catch and kill a fairly large sow or boar.  Although variable from area to area, feral hogs can constitute a significant volume of prey in the diet of this large predator. 
Feral hog  Cannibalism or predation of feral hogs by other individuals within that same population has been documented to occur.  Such predation would be primarily directed at immature animals.  The most likely instance would involve the predation of unattended newborn piglets by adult boars.  The impact of this type of predation is unknown.  Based on extensive zoo experience with captive wild hogs, some researchers believed that such reported predation of young piglets by adult boars was unfounded.
Potential Natural Predators  Based on their overlapping range with feral hogs in this country and the fact that these predators have been documented to prey on wild hogs elsewhere, four additional potential predators of feral hogs in this country would include the Burmese python, gray wolf, lynx, and jaguar.  However, in spite of this potential, none of these four species have been documented to prey on feral hogs in the United States to date. 
In summary, the list of known and potential natural predators of feral hogs in the United States is longer than had been heretofore reported.  However, because the predation by these species is largely opportunistic in nature, the impact on local feral hogs on an annual basis would be minor under most circumstances.  Mountain lions are reported to be the only predator that uses feral hogs as prey on a regular basis; however, the percentage of hogs in a lion's diet appears to be prey density dependent in any one given area.  With the possible exception of alligators and black bears, most other species identified above would constitute only an incidental or infrequent opportunistic predator of immature feral hogs.  As such, natural predators do not have the potential to be able to significantly reduce the number of individuals in a local feral hog population. 

Can Wild Pigs Ravaging the U.S. Be Stopped?

The USDA is spending $20 million to solve a pig problem that has spread to 39 states and counting

Wild pigs like these trapped by wildlife agents come in many sizes and colors. 
Credit: Clint Turnage of the U.S. Department of Agriculture
For centuries wild pigs caused headaches for landowners in the American South, but the foragers’ small populations remained stable. In the past 30 years, though, their ranks have swollen until suddenly disease-carrying, crop-devouring swine have spread to 39 states. Now, wild pigs are five million strong and the targets of a $20-million federal initiative to get their numbers under control.

Settlers first brought the ancestors of today’s pigs to the South in the 1600s and let them roam free as a ready supply of fresh pork. Not surprisingly, some of the pigs wandered off and thrived in the wild, thanks to their indiscriminate appetites.

Wildlife biologists can’t really explain how pigs from a few pockets were able to extend their range so rapidly in recent years. “If you look at maps of pig distribution from the eighties, there's a lot of pigs, but primarily in Florida and Texas,” says Stephen Ditchkoff, a wildlife ecologist at Auburn University. “Today, populations in the southeast have exploded. In the Midwest and the north it's grown to be a significant problem.” Ditchkoff believes sportsmen transported the pigs so they could hunt them on their land.

As pigs spread, they wreak havoc on the lands they inhabit. Wild pigs cause at least$1.5 billion in damages and control costs each year, according to a 2007 survey, mostly to agriculture. Dubbed the “rototillers of nature,” they dig up fields, create wallows in pastures and destroy fences. A church in Texas was so worried that pigs would devour its annual pumpkin sale that it lobbied the local government to let hunters stand watch over the patch at night. They were right to fret. The 2.6 million pigs in Texas cause $500 million in damage each year—a liability of $200 per pig. “I’ve never seen any one species that can affect so many livelihoods and resources,” says Michael Bodenchuk, state director of Texas Wildlife Services. He is particularly worried about harm to native species and the 400 stream segments in Texas that are infected with bacteria from the pigs’ defecation.

Heeding concerns from state wildlife agencies, the U.S. Department of Agriculture created a new national program in April to halt and reverse this trend. It aims to wipe out pigs from two states every three to five years and stabilize the population within a decade. Dale Nolte, national coordinator of the program, says his first priority will be states with the fewest pigs; he will then work back to those like Texas that are overrun. One reason he wants to confront the states with the fewest pigs first is because the animals reproduce rapidly once they invade an area. If 70 percent of the pigs in a region are killed, the remaining ones can have piglets fast enough to replace all those lost in just two and a half years.

Those odds haven’t stopped wildlife agents from trying to rid their states of the scourge even before a federal program was in place. Although the traditional methods of hunting and trapping have helped, they have not stopped overall population growth. Practitioners are refining these tried-and-true methods while also exploring new ways to destroy larger numbers of pigs.

Trapping, for example, works well in areas with a low to medium density of pigs but has one major pitfall. Pigs travel in groups of eight to 15 called sounders, and trappers rarely catch all the members at once. Those that escape will learn to avoid traps in the future. Ditchkoff and Mark Smith, an animal specialist at Auburn University, teach landowners to practice whole sounder removal in which trappers patiently bait and rebait traps for days or weeks to improve their chance of capturing the entire group. “It's not how many pigs you remove,” Smith says. ”The real question is, How many pigs did you miss?”

Infrared cameras, triggered by motion sensors, are commonly used to monitor wild pig use activity prior to setting a trap. Credit: School of Forestry and Wildlife Sciences, Auburn University

Another popular way to rid a region of pigs is to hunt them from helicopters. Wildlife agents in Texas have found aerial shooting to be the most cost- effective method of pig control, even though the price can run as high as $600 an hour. Texas agents kill 25,000 pigs a year and half of them are shot at from the sky.

A team in New Mexico is using a hunting approach that employs a “Judas pig,” named for the biblical disciple who betrayed Jesus. They affix a radio collar to a pig and set it free, then follow it to its sounder. After a year of using this method state agents had eliminated 687 wild pigs and wiped them from 10 of the 17 counties where they had once roamed.

Neither aerial shooting nor the Judas pig technique is particularly well suited to the forests of the Southeast or the residential areas on which pigs have increasingly encroached. These limits are why Glen Gentry, an animal scientist at Louisiana State University, would prefer to poison pigs with sodium nitrite. “We can probably get to more of the group with toxicants,” he says. Ditchkoff agrees: “In Texas and Alabama, we need better tools than trapping,” he says. “We need toxicants and contraceptives.”

Gentry hopes to receive some of the money that will be available through the new federal program for his work in Louisiana, a state with half a million pigs. He needs to find a way to convince the pigs to eat bait laced with the bitter sodium nitrite compound and ensure that other animals will not be harmed if they accidentally consume it. Government researchers are also testing sodium nitrite as a pig poison, which has long been an effective form of eradication in Australia. If it works here, poison could be the most cost-effective solution of all.

In addition to devoting money to getting rid of pigs, the new federal program led by Nolte will spend $1.5 million to update estimates of the nation’s wild pig population and investigate the annual damage they inflict. Another $1.4 million will help monitor diseases like swine brucellosis and pseudorabies, both of which have been eradicated among domesticated pigs but threaten to make a comeback. The rest of the money will set up a centralized system to allow federal officials to better coordinate the projects in each state.


Anonymous said...

This is ONE reason human sport/subsistence hunting should NOT be totally banned, in my opinion. Let the invasives be allowed to hunt and control other invasives!....L.B.

Rick Meril said...

yep,,,,,,,,,,,,but unfortunately, not enough human hunters to slow the tide