 As with any predator at or near the top of its food chain , the cougar impacts the population of prey species . Predation by cougars has been linked to changes in the species mix of deer in a region . For example , a study in British Columbia observed that the population of mule deer , a favored cougar prey , was declining while the population of the less frequently preyed @-@ upon white @-@ tailed deer was increasing . The Vancouver Island marmot , an endangered species endemic to one region of dense cougar population , has seen decreased numbers due to cougar and gray wolf predation . Nevertheless , there is a measurable effect on the quality of deer populations by puma predation . 
 As with any predator at or near the top of its food chain , the cougar <a href='uninflect' title='1'><mark>impacts</mark></a> the population of prey species . Predation by cougars <a href='been_done' title='2'><mark>has</mark></a> been linked to changes in the species mix of deer in a region . For example , a study in British Columbia observed that the population of mule deer , a favored cougar prey , was declining while the population of the less frequently preyed @-@ upon white @-@ tailed deer was increasing . The Vancouver Island marmot , an endangered species endemic to one region of dense cougar population , <a href='been_done' title='3'><mark>has</mark></a> seen decreased numbers due to cougar and gray wolf predation . Nevertheless , <a href='dey_it' title='4'><mark>there</mark></a> is a measurable effect on the quality of deer populations by puma predation . 
As wid any predator at or near the top of its food chain , da cougar impact tdapopulation of prey species . Predation by cougars done been linked to changes in thdapecies mix of deer in a region . For example , a study in British Columbia observed that the population of mule deer , a favored cougar prey , was declining while the population of thedass frequently preyed @-@ upon white @-@ tailed deer was increasing . The dacouver Island marmot , an endangered species endemic to one region of dense cougar population , done seen decreased numbers due to cougar and gray wolf predation . Nevertheless , it is a measurable effect on the quality of deer populations by puma predation .