20 CIRCULAR 8 4, U. S. DEPARTMENT OF AGRICULTURE 



Influence of Predators 



The experimental ewes were frequently attacked by coyotes, bob- 

 cats, and renegade dogs. Death losses due to these predators were 

 high each year and additional unmeasured losses also undoubtedly 

 occurred in the form of reduced weight gains due to disrupted acti- 

 vities. The combined efforts of a Government hunter and the shep- 

 herd, who tended the sheep and who had considerable experience and 

 skill in trapping, failed to control the predators or prevent heavy 

 losses. Prior to the start of the experiment, losses were light on this 

 same area when the sheep were herded. Predator attacks increased 

 the nervousness of the sheep and made them more easily disturbed. 



Several motives for attack by the predators were apparent. Some, 

 probably the renegade dogs and immature coyotes, killed for fun and 

 caused the heaviest losses. Their attacks were infrequent but some- 

 times involved the groups in every pasture with the loss of a dozen or 

 more sheep in one night. Transient coyotes occasionally killed to 

 satisfy hunger and a female coyote or bobcat with young sometimes 

 killed one sheep each night until the den and the young were located 

 and destroyed. These females with young caused heavy losses and 

 their attacks were most frequent through late June and July when 

 the young were being taught to provide for themselves. Many of the 

 ewes lost as a result of predator attacks died from injuries received 

 while fleeing at night in rough, broken country. Attacks were most 

 numerous at night but were also recorded in daylight hours. Direct 

 observations of daylight attacks indicated that the coyotes first 

 frightened the sheep, and then killed the individuals that left the 

 group. A frightened, running sheep was at their mercy. 



An electrically charged wire spaced 6 inches from the ground and 

 the same distance below the next higher wire of the boundary fence 

 served temporarily to reduce the number of predators that entered 

 the pastures. Coyotes soon became " educated," however, and were 

 observed searching for depressions under the fence through which 

 they could crawl without contacting the charged wire. Maintenance 

 of a charged wire so close to the ground was expensive and would 

 probably not be practical on a ranch. These experiences indicate 

 that predator losses are likely to be too high in the northern Great 

 Plains to justify large-scale, free pasture grazing by Rambouillet 

 sheep. However, in northwestern South Dakota, where predators 

 are few and are closely controlled during lambing, when sheep are 

 constantly observed and extra care is provided, pasture grazing has 

 been practiced successfully. The practice may have advantages 

 elsewhere in the northern Great Plains. 



Habits Indicate Desirable Management Systems 



Because range sheep tend to return repeatedly to favored grazing 

 areas until heavy use and range damage occur, and because predators 

 are usually numerous and not closely controlled in the northern Great 

 Plains, it is inadvisable to turn sheep loose to freely graze large fenced 

 areas of range. The foregoing observations and experiences indicate 

 how knowledge of the natural habits of range sheep may be used in 

 devising handling systems that will aid in obtaining good range and 

 livestock management on northern Great Plains range. Slow, quiet 

 handling with some latitude for choosing the direction of movement 



