Wildlife and Fish in a Drought

Grazing Animals

Most Texan are familiar with fluctuations in the state’s rainfall. Variation between months, seasons or years may be as much as 400 percent with more years being below “average” than above. This varying rainfall is responsible for the ups and downs of wildlife food production in West Texas and this year it has extended into East Texas.

Game management during a drought is generally an extension of what is practiced during wetter years. With grazing animals—such as deer, pronghorns and exotic big game species—balancing the total stocking rate with the forage produced is the primary goal. Game species are seldom the only grazing animals present; domestic livestock must also be considered in game management.

Keep the numbers of breeding animals below the average carrying capacity of the range for flexibility during dry years. You can adjust livestock numbers more easily than wild species. Reducing and adding animals in the game herds generally are limited to the hunting season and fawning period.

A night counting deer with a spotlight or an aerial count with a helicopter will give information on deer numbers and herd condition for planning this fall’s harvest. Young animals are the most sensitive to nutritional conditions. Therefore, a low ratio of fawns to does during September indicates poor food conditions. To be prepared for low forage growth, manage each hunting season as though it is the one immediately preceding a drought.

Deferred rotation grazing system not only benefits livestock but also reduces competition for food since big game tend to move away from livestock into rested pastures. Rested pastures also benefit quail and turkey by providing nesting cover and allowing food plants to produce seeds.

Poisonous plant problems are more likely to grow during or immediately following drought periods. Some unpalatable plants may be eaten due to starvation conditions, and some toxic plants become abundant following rain showers. The fresh growth is attractive and animals may eat a lethal amount before learning to avoid the plant. Animals that are confine or new to the area are particularly vulnerable.

Supplemental feed may be appropriate to carry valuable animals to harvest or sale, but supplying enough supplements adequate for antler growth in young animals is costly. Unless animal numbers are reduced significantly they will continue to graze and give preferred plants little opportunity to recover.

A pronounced “browse line” on major browse species, the absence of palatable forbs, and consumption of unpalatable species such as juniper or pine indicates that forage conditions are poor. Not all plants represent food, so game managers need to be able to recognize important species.

Fish

Drought conditions or shortage of water for fish production is common in much of Texas each year. The severity of this shortage determines how much response is needed. Evaporation remains nearly constant from year to year, and without rainfall to replenish water in a pond, you will need to pump water in for the fish population to survive.

As water levels recede, fish become more stressed. Fish that are large enough should be harvested. Normally the fish population should be reduced to no more than 500 pounds per surface acre in the receding pond. Remove the largest fish first since they are the most susceptible to low oxygen levels. All fish should be removed when the water level drops below two feet.

Warm or hot water tends to add stress to the fish, reduce oxygen levels in the water and increase the incidence of disease and parasites due to crowding of the fish into smaller areas.

To alleviate the stress:

  1. Reduce the feeding rate to not more than 1 percent of body weight daily.
  2. Add well aerated fresh water to the tank or pond from wells or other water sources.
  3. Increase the oxygen levels in the water by spraying water over the pond surface.

One positive aspect of a drought is that it may give the pond owner the opportunity to carry out physical and biological renovations of the pond. Unwanted fish species can be eliminated. Accumulated sediment can be removed to return the pond to its original depth. Margins and dams can be reshaped to minimize erosion and aquatic plant growth, and emergency spillways and overflow structures can be repaired or installed.

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