Carter and Stein 



Chapter 9 



Molts and Plumages 



Methods 



We relied heavily on studies involving collected birds 

 that allowed a close examination of plumages and molt 

 condition. Sealy (1972; 1974; 1975a,b) studied breeding 

 phenology, diet and body condition of murrelets at Langara 

 Island, British Columbia, March-July 1970-1971. Carter 

 (Carter 1984, Carter and Sealy 1990, Rodway and others 

 1992) studied at-sea distribution and foraging behavior of 

 murrelets, as well as breeding phenology, diet and body 

 condition, in Barkley Sound, British Columbia, May-October 

 and December 1979-1980. Carter (unpubl. data) collected a 

 complete series of birds undergoing pre-basic molt, as well 

 as some juveniles, from July to October. These birds were 

 preserved as study skins by Sealy and are housed at the 

 University of Manitoba Zoology Museum, Winnipeg, 

 Manitoba. In addition, Carter (unpubl. data) observed Marbled 

 Murrelets off Victoria, British Columbia, during November- 

 March 1978-1980 (see Gaston and others 1993). These studies 

 were collated to present a general picture of murrelet plumages 

 and molts throughout the year for southern Vancouver Island, 

 British Columbia. 



To confirm plumage and molt patterns identified from 

 other studies, we examined a total of 106 specimens from 

 the late summer and fall periods in the Royal British Columbia 

 Museum (Victoria, British Columbia) and in the California 

 Academy of Sciences (San Francisco, California). We 

 examined total length, the ratio of dark: light coloration, 

 ventral coloration and patterning, dorsal coloration, and 



primary wing molt. Total length was measured from 46 adult 

 and 30 juvenile (including recently-fledged and older juvenal 

 plumages) specimens that had been collected during June 

 through September. The ratio of dark:light coloration was 

 determined by placing a grid marked with 0.5 inch x 0.5 inch 

 quadrats over the dorsal, left and right sides of museum 

 specimens and tallying the number of quadrats filled with 

 mainly dark or mainly light plumage. Only the dorsal surface 

 and sides of the specimens were examined in order to 

 determine the dark: light ratio for the area of the bird most 

 often seen when they are sitting on the water. Notes on the 

 ventral coloration and patterning and dorsal coloration were 

 also recorded for 67 adult and 35 juvenile specimens. 



Plumages 



Basic and Alternate Plumages 



Kozlova (1957) provides good general descriptions of 

 the basic and alternate plumages of the Marbled Murrelet. 

 The following is a summary of Kozlova (1957) with a few 

 added comments. In basic plumage, adults are dark brownish 

 above, with bluish grey margins to the back feathers and 

 largely white scapulars. The sides of the head and band 

 around the neck, extending almost to the nape, are white. 

 The underparts are white with some brown feathers still 

 sprinkled on the flanks (figs. 1 and 2). In alternate plumage, 

 the upper body parts are brownish black with rusty-buff 

 margins to the back feathers. The sides of the head, front and 



Figure 1 Plumage similarities during fall between older juvenile Marbled Murrelets (top) and adult birds (bottom). Collection dates of juveniles: 5 

 October 1907 (left), 8 November 1907 (right). Collection dates of adult birds: 23 September 1895 (left), 16 November 1895 (right). Specimens are 

 housed at the California Academy of Sciences, San Francisco, California. Photo taken by H.R. Carter. 



100 



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



