DISCUSSION 



IMPORTANCE OF COLONY SITES 



Interest in protecting the seabirds and wading birds of Maine has been 

 at a high level ever since the turn of the century. Many ornithologists have 

 estimated populations of some species at frequent enough intervals to deter- 

 mine the increase or reduction of numbers. Even though some early estimates 

 were rough, it is evident that the numbers of alcids, large gulls, cormorants, 

 and eiders have increased substantially from their near extirpation in the late 

 1800's. The numbers of terns, laughing gulls, and herons do not appear to 

 be as high as in the past. Undoubtedly, certain ecological or environmental 

 factors are operating to limit populations. Population levels of the Leach's 

 storm-petrel have never been accurately assessed in Maine. It is hoped that 

 the numbers of pairs estimated for petrel colonies will provide a base for 

 comparison with future information. 



The historical information compiled during this project documents the 

 presence of colonies on particular islands as far back as 75 years and illus- 

 trates that some species shift their colonies from one site to another. A 

 study of the historical information confirms the importance of Maine coastal 

 islands for nesting seabirds and wading birds. All islands in Maine, especial- 

 ly the "bird" islands, deserve protection because they are discrete ecological 

 units which can be destroyed wery gradually or \/ery quickly depending upon 

 the forces which are operating. 



The 1977 inventory data has a current value and a historical value. For 

 those colonies with an historical record, the 1977 species data will add another 

 link to that record. For those colonies without a historical record, the 1977 

 data will establish a base to add to in the future. The data must be used in 

 light of not only other ecological data but also in terms of man induced 

 changes in the environment. For example, several colonies with long term 

 historical records did not appear to have bird populations as high in 1977 as 

 were recorded in previous decades. By talking to local island owners, pre- 

 disposing causes for the decline were recognized. Grazing of domestic 

 livestock, burning, timber cutting, quarrying, and house building may result 



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