In our modern age, we can be closer together than ever before; the advances in communication, trade, and mobility have resulted in a connected world. This has many benefits, but unfortunately, unforeseen consequences, such as invasive species. An invasive species is an organism that enters a habitat not its own through various means and can decimate the local ecology of wherever the species goes. An invasive species can be any living creature from an insect, plant, and even mammal. One such species is the Feral Hog, also known as the Wild Hog or Wild Pig. This species has invaded most of the states across America, and two of the worst affected states are California and Texas. This paper will analyze the origins of this invasive species, characteristics of the species, and the damage this species does to these states. Furthermore, using the current population statistics and statistics on current measure being taken to curb this species, an estimate will be calculated to see how the population may grow by the year 2025.
To begin, it is important to learn more about this species. the term “Feral Hog” is a slightly incorrect term attributed collectively to Eurasian wild boars and Feral Hogs. Eurasian wild boars originate from Russia whereas Feral hogs are hogs that were domesticated pigs that adapted to living in the wild. Domesticated pigs are able to become feral hogs within months of being released into the wild. They grow bristles and thick hair, and within a few generations will grow tusks very similar to their Eurasian counterparts. They are also able to interbreed with Eurasian wild boars (Mapston, 2007). Due to this, there are very few boars of pure Eurasian decent, meaning the term “Feral Hog” has become correct as time has passed. Feral Hogs can reach sizes of over 600 pounds and typically have 2 litters in a year with a litter size that can range from one to twelve. The average hog will live roughly 4 years in the wild (Feralhogs, 2019).
Concerning the introduction of the eventual feral hog to California and Texas, the species was introduced as far back as the 18th century. Feral hogs in the United States were introduced in the 1700s by Spanish missionaries (Schellman, 2018). The missionaries would let domesticated pigs loose so they could breed, and with colonization of the area, their population increased as they were considered a good source of food. It’s similar in Texas, however, the Eurasian wild boar was introduced into the population in the 1920s and 1930s by ranchers to hunt for sport, which further added to the population. In the three centuries they’ve been here, the population has grown to the point that in Texas, feral hogs do over $400 million in damages (Morthland, 2011) annually. In California, the damage is estimated at $1.5 billion dollars every year (Schellman, 2018). The population for California is anywhere between 200,000 and 400,000 (Sabalow, 2018). In Texas, the number is estimated from 1.8 to 3.4 million pigs (Timmons et al., n.d.) ). Each year, the pig population grows by roughly 20 percent, despite control methods that are in place to lower the total population (Timmons et al., n.d.).
It important to explain the destruction this species can cause. The United States Department of Agriculture has published 5 areas in which a feral hog can cause damage, they are: agriculture, pets and people, natural resources, property, and cultural and historic sites (USDA, 2016). This analysis will cover 3 of the most important ones.
Feral hogs affect agriculture by consuming crops or simply trampling over them. They will commonly target sugar cane, corn, grain, wheat, and rice but they will eat nearly any crop they have access to. Furthermore they damage pasture areas by digging for roots of plants, which will kill valuable plants and allow weed species to prosper. Feral hogs can transmit diseases to livestock, and can easily kill the young of livestock species (USDA, 2016).
In regards to people and pets, feral pigs can carry over 30 diseases that can be transmitted to humans and pets. One other notable risk is that feral pigs are known to be territorial and aggressive and can attack individuals but fatalities are rare (USDA, 2016). However, this past November a Texas woman, Christine Rollins, was killed by a pack of feral hogs in a Anahuac, a town 50 miles east of Houston. It is especially rare for attacks to take place in suburban and urban areas; but according to John Mayer, who published a 2013 study on feral hog fatalities, feral hog presence in these areas has been increasing since the mid-1990s (Bellware, 2019) .
The damage to natural resources by feral pigs are due to the impact on wildlife. The pigs will prey on nests and eggs of birds and reptiles. They will compete with deer, bear, and turkey. Furthermore their wallows make for ideal mosquito breeding grounds which also allow disease to spread ((USDA, 2016). In all, the feral pig is an extremely destructive species for the reasons listed and many more.
Continuing, there a variety of control methods utilized in an attempt to curb the boar population. The most common method is hunting. In California, the primary method used to control the wild pig population is a firearm, accounting for 84.3% of total takedowns for the 2016-2017 year. Takedowns with bows and crossbows accounted for 5.8% of the total, with the remaining 9.9% method being unknown (Garcia & Raymond,2017) . Texas uses very similar methods to California; however, trapping is also used and is the most common form of population control with 48% of takedowns being reported using the trap method. The second most common reported method is takedown by firearm, accounting for 35% of reported takedowns (Timmons et al., n.d.).
With this information, it is possible to make an estimate of what the feral pig population will look like within the next five years if current methods stay the same. First, let’s look at California. Estimates of the feral pig population vary from 200,000 to 400,000. We will use an average of 300,000 for the year 2019 (Sabalow, 2018). The population has the average growth rate of 20 percent each year. Using data from the Department of Fish and Wildlife in 2016-2017, only 4,637 pigs were reported taken for the season (Garcia & Raymond,2017). This is %1.5 percent of the total estimated population. Annually, the feral pig population will grow by %18.5 percent. With this known, the feral pig population will have reached roughly 1,030,000 by the year 2025. Starting with the damage of $1.5 billion annually, the current population shows that each individual pig does an estimated $5000 worth of damage per year.
\[ \frac{1.5 \times 10^{9}}{300 \times 10^{3}}= $5000 \text{ per pig}.\]
If current measures stay the same, California will face over $5.15 billion in damages annually from the feral pig population. Furthermore, when adjusted for an average inflation rate of 2.3% per year (Knoema, n.d.), that number will actually be $5.92 billion in damages in the year 2025.
\[ \text{ California: Population Growth/ Estimated Cost by Year 2025}.\]
\[ U (1-d)^n\]
\[ U (1- .185)^6 = 300 \times 10^{3}\]
\[ U (.82)^6 = 300 \times 10^{3}\]
\[ .29U = 30 \times 10^{3}\]
\[ U= 1.03 \times 10^{6} \text{ Feral Pigs}.\]
\[ 1.03 \times 10^{6} \text{ Feral Pigs} \times $5,000 = $5.15 \times 10^{9} \text{ dollars}.\]
\[ \text{ 2025 Estimated Cost Due to Annual Inflation Rate}.\]
\[ U (1-d)^n\]
\[ U (1- .023)^6 = $5.15 \times 10^{9}\]
\[ U (.977)^6 = $5.15 \times 10^{9}\]
\[ .87U = $5.15 \times 10^{9}\]
\[ U= $5.92 \times 10^{9} \text{ dollars}.\]
Concerning Texas, the population of feral pigs is much higher, with population estimates ranging from 1.8 to 3.6 million. For the purposes of this paper, 2.6 million will be used as the base population for 2019. Texas A&M Institute of Renewable Natural Resources published a study showing that the average population growth rate annually is 21% (Timmons et al., n.d.) . Using this data, by the year 2025 Texas will have a feral pig population of roughly 10,800,000 with the population increasing by over 1 million each year. With an estimated $400 million in damages annually, the average feral pig causes only $154 in damage, much lower than California.
\[ \frac{400 \times 10^{6}}{2.60 \times 10^{6}}= $154\text{ per pig}.\]
Despite this, by the year 2025 Texas will be dealing with $1.66 billion in damages. When adjusted for inflation with the same interest rate (2.3%) that number is actually much higher at $1.91 billion dollars.
\[ \text{ Texas: Population Growth/ Estimated Cost by Year 2025}.\]
\[ U (1-d)^n\]
\[ U (1- .21)^6 = 2.60\times 10^{6}\]
\[ U (.79)^6 = 2.60\times 10^{6}\]
\[ .24U = 2.60\times 10^{6}\]
\[ U= 10.8\times 10^{6} \text{ Feral Pigs}\]
\[ 10.8 \times 10^{6} \text{ Feral Pigs} \times $154 = $1.66 \times 10^{9} \text{ dollars}.\]
\[ \text{ 2025 Estimated Cost Due to Annual Inflation Rate}.\]
\[ U (1-d)^n\]
\[ U (1- .023)^6 = $1.66 \times 10^{9}\]
\[ U (.977)^6 = $1.66 \times 10^{9}\]
\[ .87U = $1.66 \times 10^{9}\]
\[ U= $1.91\times 10^{9} \text{ dollars}.\]
In conclusion, The feral pig population is increasing at a rate higher than what the current control measures in place are capable of reacting to. Unfortunately, these numbers are only an estimate using data that even experts themselves are not entirely sure of due to the difficulties of trying to track such an aggressively reproducing species. Feral pigs cause billions of dollars worth of damage to the places they take over as well as spreading disease and are even capable of killing people. Despite this, there seems to be very little being done about this issue, and it’s important to know what can happen if things remain the same.
Bibliography
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Bellware, K. (2019, November 26). A herd of feral hogs attacked and killed a woman on her way to work in Texas. Retrieved from https://www.washingtonpost.com/nation/2019/11/26/feral-hogs-kill-woman-texas/
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