2 
 
 
      In the following captions, the fragments of *leads* now available 
 
 are discussed. 
 
 Predation. Irruptions do not immediately follow removal of predators. 
 
 Thus in Pennsylvania predators were removed in the 1700's , but irruptions

 
 did not begin until the 19201s. 
 
      Absence of effective predators may, however, predispose a range to

 
 irruption. I know of no irruptions in the presence of predation. I 
 
 know of dense herds in Mexico which have wolves and lions, and do not 
 
 irrupt. 
 
      What are effective predators? Presumeably wolves and lions. Were 
 
any deer ranges originally devoid of either? This is a critical point. 
 
Parts of the Northwest may have been. 
 
      What was the original deer-predator rat~s? harly Journals show 
 
an astonishing scarcity of deer in parts of Utah, Arizona, and along the

 
upper Columbia. Some of this range is now irruptive. 
 
      The present cooperative predator-control operations offer many 
 
chances for experimental work which, as far as I know, are not utilized.

 
What are the mechanics of lion concentration on incipient irruptions, 
 
i.e., high spots? From what distance do they come? What sexes and ages? 
 
Does such concentration leave a vacuam elsewhere? Tagging could throw 
 
light on these questions. 
 
     What selectivity in prey holds for lion sex and age classes? One 
 
hears that only old weak-toothed lions attack sheep. A tagged lion 
 
population might verify or sharpen this purely empirical conclusion. 
 
If it is true, then the impact of lions on deer might be strengthened, 
 
and that on sheep weakened, by selective control. If this study should, 
 
in the end, indicate the advisability of predator management for deer 
 
control, then advance information on these critical questions might be of

 
great value. In any event, such information has ecological value.