Predators & Population Control

Preseason Duck Checklist: Part 2
October 18, 2016
CWD
What Texas Hunters Need to Know About New CWD Rules
October 21, 2016

Is the Targeting of Predators Across Texas the Best Game Management Strategy?

There is no question some areas of Texas have too many deer.

Certain parts of the Texas Hill Country, along the coast and in the South Texas plains are above their carrying capacity. It has been a long time since Texas has seen a massive disease outbreak and die-off, but it could certainly happen in some areas.

Predator control is something being discussed more and more as deer hunting has transformed from a pursuit to a full-on multi-million dollar industry. Coyotes in particular are the target of aerial shooting, poisoning, trapping and intense hunting in certain areas.

Is this justified? Or should we do even more predator control?

Although some areas have too many deer, others are seeing a decrease. Are predators to blame?

It is always best to look at scientific studies on issues such as these. I would like to examine coyote and other animal predation in low fence areas. High-fenced zones are a whole ’nother scenario.

Let’s start with an interesting paper I came across. It was put together by Terry Blankenship of the Welder Wildlife Foundation, and it looks at a variety of predation.

“Studies conducted in the Big Bend region of Texas indicate desert mule deer were found in 24 percent of bobcat scat from 1972-74. A decline in deer populations and an increase in rabbit populations resulted in a decline to three percent for deer and an increase of rabbit in the scat from 51 to 78 percent. (Leopold and Krausman 1986).”

“Beasom and Moore (1977) recorded white-tailed deer in six percent of stomachs examined in south Texas during 1971. However, no deer were recorded the following year. Cotton rats and cottontails increased in abundance during the second year. Beasom and Moore (1977) suggested bobcats concentrated food gathering efforts on the more abundant cotton rats and cottontails.”

He noted that research conducted on the Welder Wildlife Foundation from 1993-1998 indicate deer were found in bobcat scat from May through August. Deer were found in 5, 32, 24, and 4 percent of bobcat scat collected in May, June, July, and August, respectively (Blankenship 2000).”

“This corresponds to the fawn drop on the Welder Wildlife Foundation. Data show the birth period begins in May with the majority born in June.”

The golden eagle was another predator examined in this paper.

“Larger mammals (e.g. deer) may be important in the diet as carrion. Young fawns are more likely targets if they are hunted as prey. The remains of young deer were found in four of 41 golden eagle nests from west Texas and New Mexico and comprised 0.4 percent of the food items identified. The major food items in the golden eagle diet were rabbits (69 percent) and squirrels.”

Scott Henke of the Caesar Kleberg Wildlife Research Institute put together an interesting treatise on coyote control.

“Although white-tailed deer and bobwhite quail reproductive success increased with coyote removal, overall population densities for both species remained unchanged. This implies that a compensatory mortality mechanism is involved with these populations and that potential population increases of certain game species due to coyote removal are short-lived. All studies indicated that coyote control caused an immigration of coyotes into the removal areas. Coyote population densities returned to pre-removal levels typically within three months after removal efforts ceased.”

Another study he noted involved aerial gunning from a helicopter and ground calling to remove coyotes from two randomly-selected study sites every three months for two successive years.

“Intensity of removal efforts per season was 27 helicopter hours and 25 man-hours of hunting. Linear distance between coyote removal and non-removal areas was 12 miles. Coyotes also were removed from a three-mile buffer zone surrounding each site. Animal abundance and densities were assessed from the center of the removal and non-removal areas.”

Henke wrote that Texas studies that involved short-term coyote removal programs did not note differences in rodent and lagomorph populations. However, those studies that consistently removed coyotes throughout the year began to realize population-level changes after a minimum of nine months of coyote removal.

Noted biologist/deer researcher and outdoor writer Bob Zaiglin wrote about an interesting study conducted in South Texas in the 1980s.

“A genuine concern when protecting coyotes in order to enhance herd control is the indiscriminant manner in which they kill. Obviously, most deer managers prefer to select which animal (at least sex) that is harvested,” he wrote.

“The coyote is a non-selective predator and will kill adult post-rutting bucks as well as doe and buck fawns. However, for those landholdings closed to sport hunting, the coyote may be the only population control factor (other than the climate) and thus must be understood and utilized.”

He noted in the study that based on the overall information discovered in the story, “Our harvest scheme, which included coyotes as a harvesting mechanism, impacted the herd dynamics initially, i.e., doe numbers decreased and buck numbers increased. However, once the doe harvest was reduced in 1990, it became obvious that coyotes alone could not hold this population at a static level.”

“In conclusion, it is my opinion that predation by coyotes, in conjunction with low intensity doe harvests (typical in this area), can control deer numbers on large (non high-fenced) management areas. Thus, on land tracts owned by individuals unwilling to allow adequate hunters on the land to reduce doe numbers, the coyote represents a viable tool in deer harvest management.”

These studies were presented so you can make decisions on predator control on the properties you hunt and manage. Without question, coyotes, bobcats and other predators prey on deer and other game animals. How much impact they have varies and so does the impact of predator control.

It is best to move forward with your management with all of the facts, not just speculation. Maybe you have too many coyotes.

Then again maybe the coyotes are your best friend if you have too many deer on large tracts of land.

Story by Steve Schaffer

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