Procedures for Evaluating Predation on Livestock and Wildlife
Dale A. Wade and James E. Bowns
Carnivore predation on other species is a natural event that occurs throughout their range. In some cases, it may provide an essential part of control for some wildlife populations; however, it may be harmful to other wildlife populations and is detrimental to livestock production. In addition to livestock, native and exotic wildlife are lost to predators on both public and private lands, including game ranches and preserves. In determining the cause of these losses, the general criteria used to evaluate predation on livestock may be applied to other species.
Evidence of predation is normally present where large animals are killed but is frequently absent with small animals which may simply disappear without a trace. The presence of predators and predator sign in the area, in addition to hair, feathers and other remains in predator droppings (feces), even when simultaneous with livestock disappearance, are not sufficient evidence to confirm predation. Predators often scavenge animals dead of other causes and livestock can disappear in other ways.
Animal losses are easiest to confirm and evaluate if examination is conducted soon after losses occur. Examination of wounded animals and fresh kills is relatively simple. Carcass decomposition, which is rapid during warm weather, obliterates evidence. Scavenging birds and mammals also can eliminate evidence, frequently in a few hours.
In separating predation from other mortality factors, the following information may be required:
1. Predator species present in the area
2. Habits and signs of each predator species
3. History of depredation problems in the area
4. Normal and abnormal livestock appearance and behavior
5. Common causes of livestock losses other than predators:
a. Starvation and/or exposure
b. Internal parasites
c. Bacterial and viral diseases
d. Pregnancy disease and other metabolic diseases
e. “Hardware” disease caused by ingestion of nails, wire or other metal objects which penetrate walls of the digestive tract
h. Poisonous plants and moldy feeds
i. Other poison sources such as chemicals and lead-based paints, or discarded batteries
k. Snake bite
In some instances, the causes of death are obvious; however, in many cases they may be obscure. When the cause of livestock loss cannot be readily determined, assistance may be necessary. Veterinarians can identify and treat internal parasites and other diseases which kill livestock. Where poisonous plants cause loss, county Extension agents and range specialists can help identify these plants and devise corrective management procedures. Poisoned animals may require treatment by a veterinarian