OVERWINTERING GULLS AT THE 
     
     CHARLOTTETOWN SANITARY LANDFILL 
     
    
   
   
    
     by Geoff Hogan and Sue Stephenson 
     
    
   
   
    
       
     
    
   
   
    
     The use of garbage dumps and sanitary 
     
     landfill sites by gulls is a common occurrance 
     
     in North America and elsewhere. Fresh garbage 
     
     deposited daily provides a regular and depend— 
     
     able food source for these opportunistic birds. 
     
     The impact that this food source has on gull 
     
     populations is believed to be a contributing 
     
     factor to the increase recorded in many areas, 
     
     particularly of the Herring Gull. 
     
    

    
     Between January 15 and 24, 1982 several 
     
     trips were made to the Charlottetown Sanitary Great Black-backed Gull 
     
     Landfill in East Royalty to observe the species 
     
     of gulls, their relative numbers and how they made use of the site. Herring and 
     
     Great Black-backed Gulls were the most numerous species on each visit. The 
     
     actual numbers were difficult to determine due to the constant activity; however 
     
     estimates were generally 400-500 Herring Gulls and one hundred plus Great Black- 
     
     backed Gulls. Adults and immatures of both species were present. On each visit 
     
     one or two Glaucous Gulls were seen and, on one occasion, a single Iceland Gull 
     
     was observed. Interestingly, Iceland Gulls were probably the most common gull 
     
     observed within Charlottetown during the same period. Other birds regularly seen 
     
     at the site included Common Crow, Northern Raven, Starling and House Sparrow. 
     
    

    
     The gulls spent their time between feeding on the garbage heaps and resting 
     
     on nearby loafing areas. These activities were dependent upon the time of day 
     
     and the amount of dumping going on, Activity ranged from the frenzied feeding 
     
     behaviour during the morning hours, when gulls literally swarmed over the site, 
     
     to the more relaxed periods during late afternoon when most birds rested nearby 
     
     with only occasional forays to the garbage piles. At the approach of dusk the 
     
     gulls left the dump, flew approximately 2 km south, where they gathered in large 
     
     flocks on the ice of the Hillsborough River. As was typical of behaviour 
     
     recorded at the loafing areas of the dump, Great Black-backed Gulls again chose 
     
     the more exposed positions of the flock while Herring Gulls settled closer to the 
     
     center. 
     
    

    
     While feeding on garbage, interactions between the gulls were frequent but 
     
     there was no apparent dominance of one species over the other. Particularly 
     
     aggressive individuals of either species were generally the victors in any dis— 
     
     putes. Most interactions on the loafing area were between ravens and gulls. 
     
     While the gulls sat quietly, individual ravens wandered among them, occasionally 
     
     grabbing hold of a gull by a wing or tail. The sur- 
     
     prised gull reacted with protest and threats, whereupon 
     
     it was released and quickly settled d0wn. The raven 
     
     '6;§§LEF then moved along to annoy another gull. Whether this 
     
     iS§$§EEf"' behaviour on the part of the ravens was to obtain food 
     
    

    
     by causing gulls to regurgitate, or whatever, it was 
     
     very amusing to watch. The consequences however may 
     
     - be far more serious as implicated by the article by 
     
     Daryl Guignion appearing elsewhere in this issue. 
     
     Herring and Great Black—backed Gulls are adaptable 
     
     birds, quick to take advantage of food sources made 
     
     Herring Gull available by man. Both species frequent the vicinity 
     
    
   
   
    
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