BLACK-LEGGED KITTIWAKE ( Rissa tridactyla) 



Status . --Common fall and early 

 the Continental Shelf, seaward of 10 



spring transient and winter visitant over 

 km offshore (Fig. 28). 



Earliest fall record . --26 September 1976. 



Latest s pring record . --29 May 1977 (late April normal). 



Kaximum counts. --921 in 10 h, 10-113 km ESE Ocean City, 4 December 1976; 

 533 in 8 h, 72-96 km offshore, 7 February 1975. 



Remarks . --The black-legged kittiwake was considered a casual visitor to 

 Maryland by Stewart and Robbins (1958), Robbins and VanVelzin (1968) found 

 only four records for the state. In light of my recent observations (Rowlett 

 1973b), this probably reflects the lack of offshore surveys. Kittiwakes are 

 highly pelagic wanderers in winter and are rarely observed from shore. 



The southward migration in November and December coincides with similar 

 movements, by gannets. Kittiwakes in first winter plumage ("tarrocks") arrive 

 first, followed by adults. Mid-winter populations consisted of about equal 

 numbers of tarrocks and adults (Table 4). Because sub-adults in second winter 

 plumage could not always be distinguished at a distance from adults, the two 

 age classes were not distinguished during censuses. All counts in early March 

 were much lower than in early February, suggesting that kittiwakes migrate 

 north late in the winter. 



Kittiwakes were generally solitary or in small flocks of up to 25 indivi- 

 duals. Occasionally, flocks of more than 200 were seen. In many instances they 

 circled the boat once or twice, sampled the chum, and disappeared. 



lingered about 

 1000 



<n 500 



C 100 



o 



^-' 



CD 



the boat longer on stormy 



X 



X 



days than 

 X X 



on clear 



Figure 28. 



JFMAMJJASOND 



month 



1=0.1-1.0 1=1.1-10 H=ii-ioo 



MEAN NUMBER OF INDIVIDUALS OBSERVED PER HOUR 

 X = ZONE NOT SAMPLED IN THIS MONTH 



Seasonal abundance and seaward distribution patterns of the black- 

 legged kittiwakes in the northern Chesapeake Bight, 1971-1977. 



38 



