Speich and Wahl 



Chapter 30 



Marine Habitat Preferences, Variability in Washington 



ffl 



Sequim 



Canadian 



Haro Rosano 



LOCATIONS 



Georgia 



Whatcom 



San Juans 



I Spring Summer Fall . Winter 



Locations Sequim and Discovery bays; Canadian Gulf Ids., Strait of Juan de Fuca, Haro St, Rosario SL, Georgia St; 

 Whatcom and Skagit counties, San Juan Islands. 



Figure 1 Seasonal abundance of Marbled Murrelets, open water greater than 20 m depth. 



Sequim 



Canadian 



SJF 



Haro Rosario 



LOCATIONS 



Georgia 



Whatcom 



San Juans 



Spring 



Summer 



Fall 



Winter 



Locations: Sequim and Discovery bays; Canadian Gulf Islands; Strait of Juan de Fuca; Haro Strait; Rosario Strait; Georgia Strait: 

 Whatcom and Skagit counties; San Juan Islands. 



Figure 2 Seasonal presence of Marbled Murrelets, open water greater than 20 m depth. 



rich upwelled or mixed waters. Within Puget Sound, such 

 areas are normally associated with narrow passages or points 

 where currents, and mixing, are intensified. The habitat types 

 presented here reflect those conditions (table I, figs. 5 and 6). 

 Highest densities were calculated from observations 

 during the summer period from "Various Points" (fig s. 5 and 

 6) where Marbled Murrelets were recorded on over 70 percent 

 of all censuses. Densities of birds at these points were lower 

 during the spring and fall, and the percent occurrence on 

 censuses was lower, but on average, Marbled Murrelets were 

 observed on about half of all censuses during this period. 

 Only during winter did both the density and occurrence rate 

 drop below values from other periods. 



In Passages San Juan Islands, the highest seasonal 

 density was obtained for the fall period, 5.05 birds/km 2 (table 

 I, fig. 5), when birds were observed on about 40 percent of 

 all censuses (table l,fig. 6). There, numbers observed and 

 percent occurrence of censuses were much lower during the 

 spring and summer periods. During the winter period, the 

 density (1.69 birds/km 2 ) was considerably lower, while birds 

 were recorded on over 50 percent of all censuses. 



Murrelets occurred at much lower rates on censuses in 

 Admiralty Inlet, (table l,fig. 5), compared to other tidal 

 areas. However, more birds were likely present as the area 

 of this tidal passage is larger than the other tidal habitat 

 areas discussed. Similar to the other areas of tidal activity 



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



317 



