when the air above the snow is colder than -50°F. But neither a 
     
     large bird nor a small one can survive 10m; in an arctic or 
     
     subarctic winter without an ample supply of food." 
     
    

    
     My daughter in Kentville, N.S., had a flock of about 50 
     
     redpolls frequenting her feeders. She saw what she first thought 
     
     was an albino Common Redpoll, before she realized it must be a 
     
     Hoary. r 
     
    

    
     Incidentally, I had about 6 Pine Siskins enjoying my niger, 
     
     black oil sunflower, and Finch Delight seeds. I gather they are 
     
     not too plentiful this winter in other areas of the Island. I 
     
     would be interested to hear any comments. The largest number of 
     
     redpolls frequenting my backyard diner at any one time is only six. 
     
    
   
   
    
     (Replies can be sent to David at 90 Prince Charles Drive, 
     
     Charlottetown, PE ClA 3C2) 
     
    
   
   
    
     MONITORING THE HEALTH OF LOONS, GANNETS, HERONS, AND EAGLES 
     
     by Pierre—Yves Daoust, AVC 
     
    
   
   
    
     The complexity of most ecosystems often precludes the 
     
     selection of a single indicator species for monitoring their 
     
     quality. However, the health of animal species at higher levels of 
     
     the food chain represents a reasonably good parameter of such 
     
     quality. The health of these species at the population level may 
     
     be assessed through demographic studies (analysis of population 
     
     statistics), such as determination of the number of young produced 
     
     each year, but also, to some extent, by examining what goes on at 
     
     the other end of the life history of these animals, i.e. what 
     
     diseases, infectious, toxic, or other, are most often associated 
     
     with mortality. This type of investigation represents an 
     
     unobtrusive way of studying 
     
     populations of wild ~animals, 
     
     but it depends to a very large 
     
     extent on the willingness of 
     
     people in the field to collect 
     
     and submit carcasses of wild 
     
     animals to the proper agencies 
     
     or laboratories for 
     
     examination. The Canadian 
     
     Cooperative Wildlife Health 
     
     Centre (Atlantic Region), based 
     
     at the Atlantic Veterinary 
     
     College (AVC), University of 
     
     Prince Edward Island, 
     
     specializes in the necropsy (examination after death) of ‘wild 
     
     animals, including gross, microscopic, microbiological, and 
     
     toxicological examination. As a result of submission of carcasses 
     
     of Common Loons during the past year, some coming from the Canadian 
     
     Wildlife Service, others from the Nova Scotia Department of Natural 
     
     Resources (via the Provincial Veterinary Diagnostic Laboratory in 
     
     Truro), it has become apparent that a substantial proportion of 
     
    
   
   
    
       
     
    
   
   
    
     _5_