Divoky and Horton 



Chapter? 



Dispersal, Habitat Loss, and Implications 



Table J Alcid species that have recently formed new colonies in western North America 



Species 



Mtafai 



British Columbia 



Washington 



Oregon 



California 



Common Murre 



Thick-billed Murre 



Sowls and others 

 1982 



Campbell and 

 others 1975 



Vallee and Cannings 

 1983 



Speich and Wahl 1989 



USFWS '.unpubl. data 

 Newport, OR 



Sowls and others 1980 

 Carter and others 1992 



Pigeon Guillemot 



Sowls and others 



1978 



I'SFWS unpubl. data. 



Anchorage, AK 



Campbell 1977 



Speich and Wahl 1989 



USFWS. unpubl. data 

 Newport. OR 



Sowls and others 1980 

 Carter and others 1992 



Black Guillemot 



Cassin's Auklet 



Divoky and others 

 1974 



Carter and others 1992 



Rhinoceros Auklet 



Tufted Puffin 



Homed Puffin 



Campbell and 

 others 1975 



Speich and Wahl 1989 



USFWS, unpubl. data 



Newport, OR 



Scott and others 1974 



Sowls and others 1980 

 Carter and others 1992 



Byrd and others 1980 



Divoky 1982 

 Divoky, unpubl. data 



I'SFWS. unpubl. data 

 Newport OR 



Sowls and others 1980 



USFWS U.S. Fish and Wildlife Service 



areas, or growth of local populations that could only be 

 accounted for by immigration. The nesting habits of the 

 species makes the detection of any of these difficult, as does 

 the short period that the species has been the focus of research. 

 In addition, the high rate of habitat destruction recently 

 experienced (Perry, this volume) adds to these difficulties. 



Natal dispersal can be expected to be high in Marbled 

 Murrelets compared with other alcids for several reasons. 

 The winter distribution is extensive, with the species wintering 

 in the nearshore waters of the breeding range, as well as in 

 areas where breeding does not occur. The distance that 

 individual birds disperse from either their breeding or natal 

 area can be great, as murrelets are regularly found in southern 

 California some 300 km south of the closest known breeding 

 area (Briggs and others 1987). Because murrelets attend 

 inland breeding areas during the winter (Naslund 1993b), 

 information on breeding areas is provided to prospecting 

 nonbreeders at all times of the year. The prebreeding period 

 for this species is probably between 2 and 5 years (Beissinger. 

 this volume), allowing sufficient time to prospect for a 

 suitable nesting area. Additionally, the area where Marbled 

 Murrelets might discover suitable nesting habitat is a 60-km 

 band adjacent to the coast. This extensive area of potential 

 breeding habitat may have selected for more extensive 



prospecting behavior than in other alcids where potential 

 breeding sites are largely linearly distributed in a narrow 

 shoreline band. 



Methods of Dispersal 



The manner in which alcids coalesce into breeding pairs 

 can have implications for the level of breeding and natal 

 dispersal. The vast majority of breeding dispersal in alcids 

 consists of birds moving to sites either immediately adjacent, 

 or close to, the previously occupied nest site (Divoky, unpubl. 

 data). This occurs even when an established breeder initiates 

 a new pair bond with another established breeder (Divoky, 

 unpubl. data), indicating that pairing for most, if not all, 

 alcids occurs near the breeding site. If pairing occurs on the 

 water when birds are staging near the breeding location, one 

 would expect to see almost random movement of the 

 established breeders that lose or change mates. Additionally, 

 if established breeders paired on the water, the pair would 

 have affinities to two sites. 



Because ownership of a quality nest site or territory is 

 an important prerequisite for breeding, pairing at the nest 

 site allows a bird to find out whether a prospective mate 

 owns a site and to determine the quality of that site. Pairing 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



85 



