Wild pigs on the Big Island of Hawaii – friend or foe?

Wild Pigs Hawaii Tribune Herald 2020
Wailoa State Recreation Area, Hilo. Photo credit: Hawaii Tribune-Herald.

In the first months of 2020 wild pigs caused significant damage to orchards and crops at Horizon Guest House. The pigs, who live in the surrounding forest of McCandless Ranch, were in the habit of making regular raids on our property. Our gardening efforts, and attempts at protection, were left in disarray as they carved a trail of destruction.

Unfortunately, feral pigs on the Big Island of Hawaii have become a widespread problem. Wild pigs are attracted to a wide variety of food sources. On the Big Island these include crops such as macadamia nuts, bananas, avocados and pineapples. Our banana and pineapple plants were almost all destroyed over a period of months. Significant rooting damage was also done to the garden.

Wild Pig Big Island Hawaii KITV4 Island News
Photo credit: KITV4 Island News

Where did the pigs come from?

It was originally thought that the feral pigs in Hawaii were the direct descendants of those brought to the islands by Captain Cook in 1778. Captain Cook arrived with pigs, chickens and other animals. However, a 2016 study found that most of the feral pigs alive in the islands today are in fact the descendants of those introduced by Polynesians in approximately 1200 AD. [1]

That the origins of the feral pigs are not solely European will be helpful for future discussions about conservation on the islands, as well as their role in Hawaiian cultural heritage.

Wild Pigs Hawaii News Now
Photo credit: Hawaii News Now

Impact on forest ecosystems

Wild pigs also have an impact on the forest ecosystem. A study by the University of Hawai’i found that soil macroinvertebrate communities (organisms that do not have a spine but can be seen with the naked eye, such as snails and insects) remained unaffected by the presence of feral pigs in the environment.[2] However, earthworms and beetles may benefit from association with sites rooted by wild pigs.

Another study found that the absence of feral pigs over time led to increased bacterial diversity in the soil and that there was an overall increase in the ‘ecological resiliency’ of the soil.[3]

WIld Pigs Tribune Herald 2017
Corner of Komohana and Mohouli streets, Hilo. Photo credit: Tim Wright, Hawaii Tribune-Herald.

How to combat feral pigs

Pigs don’t like dogs and will tend to avoid an area if they sense or smell their presence. Culling the invading pigs is also another option, but in the case of Horizon this won’t stop the arrival of more pigs as they breed at such a rapid rate in the adjoining forest. The feral pigs are resourceful and have found creative ways of digging under the boundary fence in order to gain access.

Horizon Guest House Garden
Horizon's new garden fence

Instead we decided on a new approach. We fenced a section of the garden off completely. This area, currently housing the existing vegetable garden, will now also be where we grow the crops most vulnerable to pig invasion. New banana and pineapple plants have been planted and the existing vegetable garden has been expanded. The fence itself has been engineered to be as pig-proof as possible. Additional fence posts have been positioned close together to ensure that the fence is as tight as possible and therefore difficult for even the tiniest of pigs to burrow under.

Feral pigs might appear to be cute and relatively harmless but they continue to cause problems on the Big Island as their numbers in populated rural areas continue to rise. Creative solutions are the best way to try to mitigate their impact on a local level, while perhaps a concerted effort on a state level is needed to combat the issue further.

References

Linderholm A., Spencer D., Battista V., Frantz L., Barnett R., Fleischer R.C., James H.F., Duffy D., Sparks J.P., Clements D.R., Andersson L., Dobney K., Leonard J.A. & Larson G. (2016). [1] A novel MC1R allele for black coat colour reveals the Polynesian ancestry and hybridization patterns of Hawaiian feral pigs. R. Soc. open sci. 3, 160304. https://doi.org/10.1098/rsos.160304

Wehr, N.H., Kinney, K.M., Nguyen, N.H., Giardina, C.P. & Litton, C.M. (2019). [3] Changes in soil bacterial community diversity following the removal of invasive feral pigs from a Hawaiian tropical montane wet forest. Sci Rep 9, 14681. https://doi.org/10.1038/s41598-019-48922-7

Wehr, N.H., Litton, C.M., Lincoln, N.K. & Hess, Steven C. (2020). [2] Relationships between soil macroinvertebrates and nonnative feral pigs (Sus scrofa) in Hawaiian tropical montane wet forests . Biol Invasions 22, 577–586. https://doi.org/10.1007/s10530-019-02117-3

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Comments

  1. Ian Stark says:

    I live down the road from you across Ho’omau Ranch about 87.5 mile marker. There’s more pigs this season than I have ever seen in 40 years on island. Just today I chased off two groups of over 6 pigs each by throwing rocks. Neighbors have local hunter coming to set traps tomorrow. The guy makes the ono smoke meat! It’s the one good thing about the pig! I wish you luck with your fence. You have a beautiful spot. Lucky we live Hawaii.

    • Clem says:

      Thanks Ian. Sorry to hear about the pigs on your property! Hopefully the traps make a difference. The fence around our garden has stopped the pigs from getting in so far, but there are still a lot around this season for sure.

  2. Adam Victoria says:

    We live by the 95 mile marker and the pigs are multiplying at an exponential rate. They are coming right up to our house and seem aggressive. We have tried to build a trap and they won’t go near it. So far it has costed us thousands of dollars in fencing and traps in addition to paying people to help get them off the property and nothing has worked, in fact it is worse. They have completely destroyed all of our banana plants and rooting up our trees. We really can’t understand how there is no help from the county or state for this issue and small farms. All of the native lands and farms are going to be devastated by this issue. We already know that allowing people to hunt them doesn’t help with the numbers, it can never be enough as they can have 2-3 liters per year at up to 10 piglets! We are now getting ready to spend another fortune to put in electric fencing. It would be really nice if we could come together as a community and try and find solutions for this instead of each person individually having to take on this huge burden. We wish you luck and thank you for writing this article.

    • Angus says:

      Hi Adam, thanks for your feedback! We wish you all the best with your battle against the pigs too! It isn’t easy. Hunting them has very little effect on their population and fencing, as you know, isn’t cheap! It would be great if the county/state had a multi-pronged approach to eradication. Fingers crossed it happens soon!

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