GAS EXPLODERS 



Gas exploders periodically produce a loud explosion from the ignition 

 of acetylene or propane gas. They are partially effective as deterrents in 

 agricultural areas, but must be supplemented with other deterrents in order 

 to maintain their effectiveness. An "electronic exploder" that is currently 

 in the prototype stage would probably have similar deterrent value and might 

 require less maintenance. Neither gas nor electronic exploders have been 

 adequately tested in situations related to oil spills. 



AIRCRAFT 



Fixed-wing aircraft commonly cause some species of water birds to dis- 

 perse. Ducks and geese can sometimes by "herded" out of large areas rapidly, 

 especially if other deterrent methods are used simultaneously. Helicopters 

 are likely to be more effective because of their maneuverability and noise. 

 The effectiveness of aircraft as deterrents will vary with species, area, 

 and season; many birds dive rather than fly when an aircraft approaches, and 

 waterfowl may be incapable of flight during the molting and brood-rearing 

 periods in summer, or they may be reluctant to leave sanctuaries. Nonethe- 

 less, because of their mobility and availability, aircraft will probably be 

 one of the most useful deterrents, especially in the early stages of the 

 cleanup and deterrent operations. 



MODEL AIRCRAFT 



Standard radio-controlled model aircraft have not proved to be effective 

 in dispersing birds, and long-endurance television-equipped remotely piloted 

 vehicles are too expensive to have any advantage over full-size piloted air- 

 craft. Falcon-shaped model aircraft are more promising, but the reaction 

 of many water birds would probably be to dive into the water. It may be 

 possible to herd birds on the water with this device. A major limitation 

 of this device is that an experienced operator is required to fly it. Birds 

 may also habituate to the device fairly rapidly. 



LURE AREAS 



Food is the most common attractant used to lure birds from one area to 

 another. In special circumstances, this approach might have some application 

 for waterfowl, gulls, and sea birds. However, the lure area must be estab- 

 lished fairly close to the spill so that the birds will find the food. This 

 would probably attract birds into the general area and ultimately increase 

 rather than decrease mortality. Furthermore, waterfowl and gulls are likely 

 to feed at the lure area by day, but the return to their normal roosting sites 

 at night may again place them in a contaminated area. Therefore, lure areas 

 should be established only after a careful assessment by biologists, and deter- 

 rent efforts in the contaminated area will probably need to be continued. 



DEVICES FOR USE IN DIFFERENT TYPES OF HABITATS 



The effectiveness and logistical practicality of individual deterrent 

 methods are known or suspected to vary with habitats, species, age and sex 

 of birds, weather conditions, season, and time of day or night. Because of 

 the limited information on deterrent devices and the enormous variety of 



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