Monday, October 27, 2014

Advanced Feral Hog Trapping: Understanding Behavioral Drivers



By: Mark Tyson, M.S.

In his seven rules on hog trapping, veteran hog trapper LeRoy Moczygemba points out “there are always exceptions to the rule; one can have success with some ill-planned activity while some of the best-laid plans are for naught”. The key to reducing variability in feral hog trapping is understanding the hog’s behaviors and how those behaviors change throughout the year. In my opinion, there are five main factors that drive feral hog behaviors: thermoregulation, food consumption, social organization, habitat components and human influence. For those seeking to reduce feral hog populations in an area, it is important to incorporate these aspects of feral hog behavior into their management plan.
 Feral hogs visiting a bait site.

Thermoregulation                                                                                                            
Maintaining an adequate body temperature is of primary importance to feral hogs, especially during the warmer months of the year. During the summer months hogs will commonly be found within a mile of a permanent water source. This association with water is due to a lack of sweat glands, which prevents hogs from sweating to reduce their body temperature. During the cooler months of the year temperature regulation becomes less important to the hogs and they will range out a considerable distance from water when necessary.

Feral hog wallow.

Food Consumption
Feral hogs have a relatively simple stomach and are able to process foods rapidly, thus they have a constant need to feed. In a commercial production setting a 115 lb. hog requires over 4 lb. of feed daily; in the wild, a similar sized feral hog will need to consume that much or more based on the food’s nutrient quality. Research suggests that vegetation is the primary diet item of feral hogs, be it roots, tubers, seeds or leaves. Feral hogs will seek out seasonally abundant nutrient dense food resources throughout the year. Understanding which food resources the hogs are consuming at a specific time of the year will help in selecting the appropriate bait(s) for reduction efforts. Shelled corn is a great year-round bait to use, however items such as expired pastries, fruits, dog food, catfish bait, soured grains and flavored gelatin products also have been used successfully. Another baiting technique is to gather native mast such as acorns when they are abundant and then use them once they are no longer available.

Feral hogs primarily select vegetation, but will consume earthworms and grubs.
 
Social Organization
The interspecific interactions of feral hogs vary by age and gender. Females and juveniles often travel in family groups which are referred to as a sounder, while adult males are more solitary. The solitary nature of adult males allows them to travel between multiple sounders, seeking females in heat, thus expanding the individual’s genetic footprint. Males remain attached to a sounder for the first 16 months of their lives, which allows them to reach a sufficient body size to compete with other males in the area. When interacting with a trap, juveniles are most likely to enter, followed by adult females and lastly adult males, which often exhibit the most trap shyness.

Feral hog sounder visiting a deer feeder.




Habitat Components
When available, feral hogs will select riparian habitats; these habitats border rivers, streams and creeks. Cooler temperatures, plant diversity, dense cover, and a close association to water make riparian areas the ideal core area for feral hogs. Additionally, these areas are perfect travel corridors; I often refer to rivers as ‘feral hog highways’ and creeks or streams as ‘farm to market roads.’ Home range is a term used to describe the area of land that a species uses to meet its basic life functions. Research conducted in east Texas found that the home range of females was just over 1600 acres while males exhibited a home range of over 3900 acres. Home range sizes will vary based on the components of the available habitat, and as general rule will be smaller in high quality habitats and larger in poor quality habitats.

Riparian habitat in southeast Texas.
Human Influence
If they could have it their way, feral hogs would avoid humans altogether, but that may never be the case. In response to this, the hogs will increase their elusiveness as outside pressure increases.  In some cases such as a free choice livestock or wildlife feeders, human influence can be positive for feral hogs and they are quick to pick up on these opportunities. Landowners commonly share stories with me of trap smart hogs who evade their trapping efforts, yet researchers in Alabama reported a recapture rate of 72.5% during their study. Feral hogs are quite unpredictable and human influence only adds to that variability. If your intention is to reduce feral hog populations, it is important to anticipate how the hogs will respond to your management actions.


Box traps are one of many techniques available to land managers.


Tying it all together
Before starting your next feral hog trapping effort, consider these 5 factors and how they relate to each other, the time of year, and the local environment:

1.      Thermoregulation- Ask: What time of year is it? During late fall, winter and spring, the hogs will have much more liberty of movement due to reduced environmental temperatures. In the summertime and early fall, feral hogs will rely heavily on nearby water.

2.       Food Consumption- Ask: What are the hogs eating right now? Research tells us that vegetation is a primary diet item; your job is to determine what that might, be based on what is available. Since vegetation is important to feral hogs, learning more about the plants in your area should be important to you. Dr. Dale Rollins’ maxim on wildlife habitat management “know your plants and how to manipulate them” could not have been better stated. For the purposes of feral hog trapping, I would modify this maxim to “know your plants and how they manipulate the hogs” since the availability of vegetation governs feral hog food selection.  In the spring, plants are beginning to green up and as summer comes on additional species are added to the landscape as environmental conditions allow. The key here is to understand a plant’s nutritive value and distribution on the landscape; the hogs know this and so should you.  As fall comes along mast, from a variety of trees begins to develop. Once they drop, the hogs will focus in on these seasonally abundant resources. You may consider an investigation of the stomachs of feral hogs you have harvested to see what they have been eating. It is important to wear gloves, eye protection and a face mask to prevent the transmission of unwanted parasites and diseases when skinning or cleaning feral hogs.

3.      Social Organization- Ask: Which hogs are showing up to my trap site. Feral hogs will visit your trap site as a sounder or you may just have a lone boar appear. Research suggests that adult males are the least likely gender/age class to enter a trap, thus if a lone boar appears and is consistent, it may be better to just shoot him. On the other hand, trapping is a must for a sounder. The key to success is to understand that in a sounder there is often a “lead” or dominant sow and she will likely be the one you have to fool. Use trail cameras to observe feral hog behaviors around traps and adjust your techniques accordingly.

4.      Habitat Components- Ask: What types of habitats are found on the landscape you have permission to trap on? If riparian habitats are available, conduct a thorough investigation for signs of feral hog activity. Watch the video below to learn more about the visual indicators of feral hog activity. In the absence of riparian habitats, evaluate what available habitats contain (food, cover, travel corridors) that will benefit the hogs and begin your search there.

 
5.      Human Influence- Ask: What types of human activities occur on the area and how may they alter feral hog behavior? The activity could be a positive or negative for the hogs. If positive influences (free choice livestock feed, deer feeders, etc.) are available use them to your advantage when formulating a strategy. Negative impacts can lay waste to some of the best planning, so try to anticipate and avoid them if at all possible. Often these impacts are hard to prevent, and you may very well have to learn from experience in these cases.

No two trapping events will be alike, yet these drivers will be reflected in the behaviors of the hogs you set out to catch. After a recent speaking event, a gentleman approached me and said, “I never really thought of it that way, but it really makes sense. I’m a baker and to make great bread, I have to think about what it takes to make the perfect loaf. The same applies to these hogs, to catch a hog I guess I have to think like one.”
 
The hyper-linked resource document below will provide you with quick access to many of our online feral hog resources including publications, fact sheets and videos.