STUDY AREA AND METHODS 



The Chesapeake Biaht overlies the Continental Shelf between Cape Hatteras 

 (35°10'N, 73°32'W) and~the mouth of the Delaware Bay (ca. 39°00'M, 75°00'W) at 

 Cape Kay, New Jersey (Fig. 1). The northern half of this area was surveyed 

 with most extensive coverage given to the coast of Maryland between latitudes 

 38°30'N, seaward to Baltimore Canyon and the edge of the Continental Shelf 

 along the 100-fathom (183-m) contour. This contour lies an average of 111 km 

 (60 nautical miles) offshore (Fig. 2). 



I recorded sightings of marine birds and mammals during 784 hours (80 

 days) of observation in the northern Chesapeake Bight from 1971 - 1977. Most 

 observations were recorded from chartered sports fishing boats which carried 

 an average of 30 "birders" and naturalists (37 days from 1973 - 1977) from 

 Ocean City, Maryland, to near Baltimore Canyon. Additional observations were 

 recorded during extended cruises on oceanographic research and U.S. Coast 

 Guard vessels (22 days) and small commercial fishing boats (21 days). Tables 

 1 and 2 summarize days and hours of observation, the majority of which occur- 

 red from 1974 - 1977. 



Spatial distribution of seabirds over the Continental Shelf in the north- 

 ern Chesapeake Bight is graphically illustrated for each species observed ten 

 or more times during the 784 h of observation. Hours shown in Table 2 were 

 used to compute an average number of birds seen per hour. 



Most of my observations were m.ade with Zeiss 8 X 10 dialyte binoculars. 

 Nearly continuous watches were maintained during daylight hours from time of 

 departure to return. Individuals of all species of birds and cetaceans were 

 recorded at half-hour intervals. Boat-following birds v/ere noted in an effort 

 to minimize duplication. Specific notes on behavior and species associations 

 viere also recorded. 



Regular LORAN (LOng RAnge Navigation) "A" and "C" position coordinates 

 were recorded as described by Rowlett (1977c) at regular intervals or at stops 

 or course changes for transect plotting (Appendix A). Observation intervals 

 for bird counts corresponded to intervals between sounding contours (fathoms) 

 on National Ocean Survey Nautical Chart No. 1109. LORAN positions were record- 

 ed for all cetacean sightings, locations where animal life was concentrated, 

 and for sightings of avian species whose statuses were inadequately documented 

 off the mid-Atlantic States. 



To attract birds, coarsely ground beef suet, ground fish, stale bread, 

 fish oil, and mashed shark liver were dispersed as "chum" on all 37 charter 

 trips and occasionally on other vessels when it did not interfere with re- 

 search or fishing activities. Generally, 200 lb (908 kg) of beef suet and 30 

 loaves of stale broad were dispensed daily during winter surveys. Unless kept 

 cool, the beef suet became rancid and the gulls ignored it. During the summer 

 months, when gulls were not a part of the offshore avifauna, chumming with 

 oily, slick-forming substances including ground fish, fish oil, and mashed 

 shark liver attracted Wilson's storm petrels and, occasionally, shearwaters. 

 Chumming during the summer v/as successful only when the boat was stationary or 

 moved in tight circles so that a single slick could be maintained. Birds 



