contour (77 km offshore). Gannets were especially widespread in winter and 

 ranqed progressively further offshore with the advance of the season; the 

 highest counts were recorded near the edge of Continental Shelf in N'arch. In 

 /^pril, feeding flocks were most conspicuous over pods of fin whales when 

 Boston mackerel (Sarda s arda ) were migrating northward. At the height of a 

 mackerel "run," which might last up to 15 min, dozens of gannets gathered in a 

 feeding frenzy during which some would dive from heights of 30 m or more in 

 pursuit of small fish under the mackerel. The intrusion of the boat into 

 their midst terminated this activity and the birds rapidly dispersed. 



Observations from shore suggested that immature gannets passed southward 

 along the coast in advance of an increasing number of adults, which followed 

 in November and December. Adults far outnumbered immature birds during the 

 winter months, but in April, this trend was reversed as adults returned to 

 their northern latitude colony sites (Table 3). Most adults of the western 

 North Atlantic population winter in the Chesapeake Bight. The immatures 

 winter farther south off the southeastern and Gulf Coastal states where win- 

 ters are not so severe. This age-dependent behavioral trait is characteristic 

 of many North American migratory species. 



X X X X X 



<.l 



T r 



1 r 



A M J J A 



month 



S O N D 



I =0.1-1.0 I =1.1-10 I =11-50 Hi =51-100 



MEAN NUMBER OF INDIVIDUALS OBSERVED PER HOUR 



X = ZONE NOT SAMPLED IN THIS MONTH 



Figure 14. Seasonal abundance and seaward distribution patterns of the 



northern gannet in the northern Chesapeake Bight, 1971-1977. 



RED PHALAROPE (P halaropus f ulicarius ) 



Status . --Fairly common spring and fall transient; uncommon and irregular 

 winter visitant, usually beyond 70 km from shore (Fig. 15). 



Earlie st record . --SPRING: 27 April 1974. FALL: 11 August 1975. 



22 



