Having hunted all over Texas over the past twenty years, I can safely say that the amount of exotic wildlife that I see now compared to the numbers then are steadily increasing. It used to be that you’d drive past the ranches with high fences advertising “Exotic Hunts” and you knew that would be the only way to be able to hunt one: pay thousands of dollars for the chance to kill an axis or fallow deer, black buck antelope or elk. These days, the high fence theory has proven faulty, and those crafty beasts have found a way out! We’re seeing them on the sides of roads, outside low fenced areas, and literally by the dozens spread across pastures mixed in with domestic livestock. While many don’t understand the problem with this spread of an introduced species, let me remind you of the key word in that sentence: introduced. Non-native animals that have been transported and introduced to a habitat that they then thrive in and present direct competition to the native species that inhabit that area.
My main focus this week is the axis deer. It’s only been since Memorial Day that Leah and I have been to Tres Hermanos Ranch, but after going out this past weekend, we were shocked at the number of axis deer we saw. The ranch is fenced to keep the longhorns in, but with a low fence, offering the opportunity for wildlife to move freely in and out. One evening, we saw seven axis deer intermingling with the native white tails. While the axis deer is a beautiful animal, and quite impressive to see in person, it is an introduced, non-native species. This is important for several reasons.
(1) Axis breed year round. Axis buck can be found in hard horn at various times throughout the year. They can breed while in velvet, but the males in hard horn are dominant. They go into rut at different times, and are not synchronized with other males in a herd. This is true of the females as well. Axis doe can begin breeding at around two years of age, and go into estrus at various times throughout the year. It is estimated that one doe can produce four fawns in three years, and can reproduce until up to age 15. This can lead to a very large axis population in a short amount of time, all of which compete with native white tail deer for food. Which brings up the second problem.
(2) Axis deer are browsers and grazers. Their primary diet, like that of the native white-tail, consists of foraging on broad leafed weeds (forbs) as well as browsing, typically on live oak and hackberry. Yet unlike the white-tail, once an area has been cleared of forbs and browse, axis can shift to grazing grass. White-tail are unequipped to digest mature grasses, so once their food supply has run out, they must leave the area in search of food. This works if the area of low fenced, but in high fenced areas where the white-tail cannot escape, they will starve.
If an area is high fenced to contain big game exotic animals, it poses more of a threat to the native white-tail deer population. Studies have shown that high fences are used as a general means to keep exotic game in, however, they do not allow any white-tail deer in or out of that same area, thus eventually ending the land owner’s white-tail population. One study conducted in the 1970’s concluded that in a high fenced tract of 96 acres that contained both white-tail deer and exotic game, the white-tail were essentially eliminated after a period of eight to nine years. This is true on a much larger scale as well (4,000 acres) and the result was the same. It is generally accepted that even if you have an area high fenced, exotics will eventually get out. See this Texas Parks and Wildlife article on exotics in Texas: http://www.tpwmagazine.com/archive/2007/apr/ed_3/
If the land owner has a low fence to allow passage of all wildlife in and out of the property, then there’s a good possibility that the escaped exotics will migrate through the area as well, again competing with native white-tail for food. Should a landowner have any domestic livestock on their property also, the presence of exotics just adds more pressure to this dynamic. Domestic cattle, goats and sheep will live on all three types of forage available: forbs, browse and grass. While it is possible to have a properly managed population of domestic livestock and native white-tail, the incoming exotics will win out over the white-tail, eventually forcing them off the property in search of food elsewhere. This is especially true in times of drought such as we are currently experiencing throughout Texas, where even the native grasses are reduced to crispy shrivels and all animals are competing for the limited amount of browse and forbs available.
The solution for a healthy population of any species, be it native, domestic or exotic animal is proper Wildlife management. At our ranch, this means keeping the amount of domestic livestock to a low number, harvesting does and spike bucks, and year round hunting of all exotics and feral hogs to keep their numbers from increasing. Despite attempts in this direction, we’ve seen the inevitable increase in the number of exotics, especially axis deer, even in the last few months, as water becomes more scarce and animals compete for food. Luckily for us, axis meat is damn tasty and a problem that we don’t mind having on the ranch just so we can harvest them for food. While it may not be our choice to stock exotics, they are there, and we’ll continue to manage as best we can so that our white-tail population remains strong, and we encourage other landowners do the same.