128 BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



a sufficient amount of palatable feed. Even under these circum- 

 stances serious damage is uncommon, as indicated by the fact that 

 pastures in which reproduction is making good progress are as a 

 rule overgrazed. Since from 80 to 90 per cent of all grazing damage 

 to young seedlings is attributable to sheep, the term " sheep dam- 

 age " is used in this report to cover all classes of injury by grazing, 

 unless there is reason to believe that other animals are responsible 

 in more than the usual degree. 



SEASONAL DAMAGE. 



Relative damage during different seasons was considered only in a 

 casual way in this study. It confirms Hill's conclusion that little 

 damage occurs in the spring of the year before the new seedling 

 shoots make their appearance and while bunch grasses are tender 

 and palatable to sheep. Usually the new growth begins about June 1. 

 In 1920 it was later on account of the backward season. Table 30 

 shows that on sample plot 5 very little damage had occurred prior 

 to July 1 of that year. This was apparently due to the fact that 

 sheep had grazed very lightly on this area during the month of June, 

 although they had covered it thoroughly in May. In average sea- 

 sons considerable damage may be expected after June 1. By about 

 September 1 both leaves and stems have become woody and resinous. 

 This probably accounts for the decrease of damage in the fall, as 

 shown by Hill's figures. It should be borne in mind, however, that 

 if other conditions are such as to induce damage, the difference in 

 various seasons may be relatively small. 



Considerable damage may occur late in the fall or early in the 

 spring, at times when unseasonable snows render herbaceous forage 

 temporarily unavailable. Sheep are usually out of the yellow pine 

 forest during the seasons when heavy snows are liable to occur. In 

 October, 1920, however, many bands were marooned on the Coconino 

 National Forest by a heavy snow. At one camp, where several 

 bands were held for a week during this storm, nearly every seedling 

 between 1 and 3 feet in height was defoliated within a radius of a 

 mile of the camp. Much cattle damage was also in evidence at this 

 time. 



Overgrazing. — Hill states that overgrazing is responsible for most 

 of the damage by sheep. Overgrazing may be due to overstocking 

 on the range as a whole, or to localized overstocking, such as results 

 from improperly distributed watering places, continued bedding of 

 sheep on the same grounds, unnecessary trailing, and other well- 

 known abuses. It is pointed out by Hill that a range may be over- 

 stocked by sheep because of a deficiency of suitable forage for them, 

 although there may be an abundance of feed for cattle and horses. 

 This type of overgrazing is common on the bunch-grass range. 



