CHAPTER VII 



PREDATION 



By Robert W. Darrow 



COMPETING INTERESTS 



ROLE OF PREDATION 



Effect During Each Life Period — Nest Period — Brood Period — Adult Period — 

 Predator Fluctuations — Buffer Fluctuations — Predator Pressure ■ — Grouse- 

 Predator Ratios — Vulnerability — Significance of Predation 



APPRAISAL OF THE VARIOUS SPECIES 



Grouse Predators of the Northeast — Rei^tionships During Each Life Period • — 

 Nest Period — Brood Period — Adiill Period — Net Effectiveness Throii.hoi t the 

 Year — Food Habits in New York — Fox — Weasel — Skunk — Raccoon — Mink — 

 House Cat — Great Horned Owl — Barred Owl — Snowy Owl - Goshawk — Cooper's 

 Hawk — Sharp-shinned Hawk — Red-tailed Hawk — Red-shouldered Hawk — Marsh 

 Hawk — Interpredator Relationships 



THE PROBLEM OF CONTROL 



Experiments Conducted — Effect on Predators — Results During Each Life 

 Period — Nest Period — Brood Period — Adult Period — Effect on Productivity 



&<. 



SUMMARY 



Predation is a fundamental relationship of living organisms funt iioiiing. through the removal 

 of surpluses, to keep their numbers within limits compatible with the habitat they occupy, 

 (p. 308). 



Although increases in a grouse population cannot be accumulated year after year, predators 

 or no |)redators. control of foxes and weasels may be useful in producing a greater fall 

 surplus on areas where such a crop will be utilized for sport, (p. 331. 350). 



\m a\crage of approximately 39 per cent of the grouse nests observed by the Investigation 

 have been broken up. mainly by predators, (p. 311). 



Foxes, the principal grouse nest predator, have broken up more nests when buffers were 

 scarce than when they were abundant, (p. 3151. 



Only about half the usual brood mortality seems attributable to predation. (p. 317). 



