and record distress and alarm calls of the many aquatic and marine bird species 

 for which such calls have not been documented, and thereafter, field trials 

 should be conducted in situations relevant to oil spills to determine their 

 effectiveness as deterrents. 



SOUNDS OF PREDATORS 



The deterrent value of sounds of predators has not been adequately tested, 

 particularly for marine species of birds. Underwater broadcasting of killer 

 whale vocalizations may be of value in dispersing some marine birds. Above- 

 water broadcasting of calls of hawks or falcons may also be useful in certain 

 situations. However, neither of these methods has been tested in relevant 

 situations. 



AV-ALARM 



Av-Alarm, a proprietary device that broadcasts loud synthetic sounds, 

 has shown some value as a deterrent in agricultural applications and has been 

 reported to have been partially effective against waterbirds in coastal areas. 

 The frequencies broadcast are chosen on the basis of their similarity to the 

 frequencies of calls produced by the birds of concern. The inference is that 

 their use will interfere with normal communication between members of a flock 

 and thus set up a stress situation that birds will tend to avoid. Additional 

 experimentation in situations related to oil spills is warranted. 



PYROTECHNICS 



Pyrotechnic devices produce a loud noise and/or flash of light, which 

 frightens the birds. Except in the case of waterfowl, pyrotechnics do not 

 attempt to mimic any hazard regularly experienced by birds. Examples of such 

 devices are shell crackers, Verey flares, rockets, mortar shells, and dynamite. 



Shell crackers are very effective deterrent devices because they produce 

 an explosion and a puff of smoke for a distance of 100 m or more from 

 the propelling device (usually a shotgun). Use of shell crackers in conjunc- 

 tion with other approaches is now a standard deterrent technique. Verey 

 flares are fired from hand guns, and produce a flare and trail of smoke, as 

 well as a "bang." Rockets have been recommended as deterrents at airports 

 and in agricultural areas. Mortar shells and fireworks fired from a 127-mm 

 launcher appear promising as deterrents because of the wide area over which 

 they would be conspicuous. However, neither rockets nor mortars have been 

 properly tested for efficacy. 



The usefulness of some or all pyrotechnics could be severely limited 

 if there is a danger of igniting the spilled oil or if there are aircraft 

 operating in the area. Moreover, people using any pyrotechnic device must 

 be trained in its use. For example, shell crackers are very simple to use. 

 However, a novice may not be aware of the facts that: (1) they should be 

 fired only from an open-bore shotgun in order to avoid possible jamming or 

 premature ignition of the explosive in the barrel ; (2) the use of more than 

 one shell cracker in a pump shotgun could cause premature firing of the 

 second shell during ejection of the spent shell; and (3) some brands of 

 shell crackers appear to be safer than others. 



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