KILIv FACTOR FOR BLACKTAIL DEER 133 



carefully compiled parts of the annual kill estimates, divide them by 

 tne census, and determine a very rough kill factor. 



The tentative figures show an average kill factor to date of about 

 1:10 or 1:1-"). Do these figures seem reasonable? I think they do. 

 The usual steer factor is 1 :(). This means that, under present con- 

 ditions, cattle have a higher productive capacity than deer. It takes 

 longer to produce a killable buck than a steer ; consequently the 

 mortality during immaturity must be higher. The fawns are preferred 

 by lions, and the calves by wolves. In general, the wolves have been 

 better controlled than the lions. A last and most important consider- 

 ation is that the deer herds have long been decimated to a point where 

 tbey are laboring against what may be called a lozvered specific 

 resistance. The lowered productivity of a decimated species is a fact 

 so well known and so often and tragically illustrated that it needs no 

 comment here. It is, therefore, reasonable to expect that, under present 

 conditions, the kill factor for deer will be lower than the steer factor. 



The kill factor to be arrived at from the statistical records so far 

 described will necessarily be a general one, determined by extensive 

 methods. It has seemed advisable, on account of the varying conditions 

 in the Southwestern District, to institute a series of intensive local 

 experiments in which the same methods will be applied with a much 

 higher degree of accuracy to small areas or "sample plots." The first 

 of this series has just been initiated on the Magdalena Division of 

 the Datil National Forest. 



The Magdalena Division is surrounded by open plains, thus obviating 

 seasonal drift, which might destroy the value of the results. It is not 

 much used as a hunting ground by tourists, thus obviating large fluctu- 

 ations in the annual kill, excessive crippling, and much difficulty in 

 obtaining accurate figures of the game killed. The resident stockmen 

 are anxious to co-operate both in obtaining an annual census and in 

 keeping a record of the game killed. Special tally books have been 

 furnished each ranch headquarters for this purpose. Predatory animal 

 conditions are normal ; that is, they are bad. The Magdalena Moun- 

 tains are an oak country, and sudden loss through starvation is 

 improbable. They contain only blacktail deer, thus ol)\iating the 

 confusion that might arise out of the difference that doubtless exists 

 in the productixc capacity of blacktail and whitetail deer. 'i1ie area 

 is small (!•!>,.'!(;() acres), and tbc i)resent census figure is ."iO head. 

 Carefully collected figures on census and annual kill arc to be obtained 

 for the next ti\e years at least. The district ranger has charge of the 



