bird species before becorring available to others. Bare ground nesters only 

 use an island for 1 to 3 yr before growth of vegetation causes them to abandon 

 the site. Ground nesting species that prefer grass and herbaceous cover will 

 use islands 2 yr of age or older depending on plant colonization and succes- 

 sion. Arboreal nesting species generally do not use a dredged material island 

 until shrubs or trees develop. Sometimes succession of vegetation is arrested 

 indefinitely by certain edaphic or climatic factors and, thus, may have long- 

 term use by a particular species. The above factors should be considered when 

 contemplating initial island construction or deposition on an existing island. 



Dredged material may be used to establish new islands when there is a 

 shortage of nesting habitat or to modify existing islands. Periodic disposal 

 can be used to set vegetation back to an earlier succession stage (to benefit 

 ground nesters). The configuration, size, and elevation can also be altered 

 through disposal. Further disposal should be prevented on islands where arbo- 

 real species are being encouraged. Soots and Landin (1978) encouraged the 

 management of existing dredged material islands, because potential adverse en- 

 vironmental impacts of disposing on an existing site are less than those of 

 developing new islands. 



Any management plan should include interagency cooperation to determine 

 habitat needs of the area (which birds do we want to encourage or discourage 

 and what type of habitat do they need?). There are several important consider- 

 ations for new island development (Soots and Landin 1978). 



(a) Site location - Isolation from man and predators is an important 

 consideration. However, with protection, colonial waterbirds can live in har- 

 mony with man. 



(b) Timing of development - Fall or winter construction will permit use 

 of the island for nesting the following nesting season by bare-ground nesters. 



(c) Size - Two to 20 ha (5 to 50 acres) are suggested as a suitable size 

 for islands. However, least terns do well on islands smaller than 2 ha. 



(d) Substrate - R..-,. i rements may vary with species. Generally coarser 

 material makes better nesting substrate than fine material. A mixture contain- 

 ing shell is good for bare ground nesters. 



(e) Slope - Flat to gentle slopes are preferred. 



(f) Elevation - Should be sufficient to prevent flooding, but high 

 elevations of fine-grained material should be avoided because of wind and ero- 

 sion. 



(g) Vegetation - Requirements vary with species. Plants can be estab- 

 lished artificially or the developer can depend on natural colonization. Soots 

 and Landin (1978) provided a comprehensive discussion of plant propagation and 

 management. For additional related information see the previous section about 

 terrestrial habitat development. 



Wetland development . Techniques of brackish-water marsh development uti- 

 lizing dredged material are fairly well developed (Carbisch 1977). Mangrove 

 and freshwater swamps and freshwater marshes could probably be developed from 



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