SHIPBOARD SURVEYS OF MARINE BIRDS 



Table 2. Meters to the end of the transect per minute into transect. 



a Meters traveled in 15 min (= start of 15-min transect). 

 Meters traveled in 10 min (= start of 10-min transect). 

 c Meters traveled in 1 min. 



1 nautical mile = 1,852 meters = 6076.12 feet. 



picture of 10 or 100 birds. Distant flocks usually appear 

 to have fewer birds than is actually the case because many 

 will be hidden by other birds or by waves and swells; some 

 birds in feeding flocks may even be sitting on the water 

 or diving beneath it. Distant vision at sea may also be im- 

 paired by atmospheric conditions such as rising heat and 

 mist, which tend to obscure birds. Do not become over- 

 whelmed with large numbers of birds; continue to count 

 numbers of birds rather than to make guesses. 



Support Data 



Before departure, observers should learn as much as 

 possible about the activities and protocol of the ship. They 

 should meet with the appropriate officers and crew to ex- 

 plain what research will be conducted and what help will 

 be needed. Techniques should be explained, stressing the 

 importance of the ship maintaining a constant speed and 

 course during observation periods. Plan your observation 

 periods ahead of time and try to stick to the plan. Let the 

 officers and crew know when you will be making ob- 

 servations and have them inform you about projected 

 maneuvers and course changes. You can leave a standing 

 call to be notified when large concentrations of birds are 

 encountered, but use these times for general observations 

 rather than transects. It is important that you conduct 

 transects throughout the survey in accordance with your 

 regular schedule. Do not add or delete transects just 

 because you encounter exceptionally high or low bird den- 



sities. In planning your schedule do not try to cram as 

 many observations into a day as possible. Remember that 

 you have lots of paper work to do for each transect you 

 take, and that you see fewer birds when you are tired. 

 It is preferable to collect a few data of high quality than 

 many data of only moderate quality. The NODC defined 

 many support fields that we have elected not to use 

 because the time and effort needed to record, transpose, 

 and analyze them would prevent accomplishment of our 

 primary goals. The two most important pieces of support- 

 ing data that must be obtained for each transect are the 

 correct position and the speed made good. 



Position 



Do not simply accept positions given by bridge person- 

 nel, especially if they are being read from a LORAN C 

 or satellite navigation system these systems can be in- 

 accurate and may vary from minute to minute. If land can 

 be detected on radar, it is best to get a position by measur- 

 ing the distance from at least two, and preferably three, 

 distinct landforms; the correct position is where the arcs 

 of the distances cross each other. Try to plot the position 

 on a nautical chart immediately to be sure there are no 

 errors, and record the depth from the chart. If the posi- 

 tion matches an electronic system such as a LORAN C 

 interpolator, it can be assumed that the electronic system 

 is correct and positions can be taken from it for the next 

 hour or two. The position should be checked at least every 

 2 h. If the ship is too far from land to obtain good distance 



