Curtain spray for control of roost ting hi ids. — 

 A "curtain" spray unit that collects and reuses the 

 toxicant has been constructed by biologists of the 

 Denver Center and was tested last spring in a 

 marsh roost near lone, Colo. The unit consists 

 of a 37-foot tower, twin 60-foot booms and catch 

 basins, and a sump tank and pump for circulating 

 liquid avicides. Blackbirds and starlings herded 

 slowly at night beneath the booms of the unit must 

 pass through the toxic spray. 



Early laboratory trials showed that starlings 

 were killed by flying through a 6-percent emulsion 

 of DRC-632, one of the promising contact poisons 

 notable for its high dermal toxicity for birds and 

 low hazard for mammals. 



Fourth year of blackbird study completed. — 

 The field phase of the 4th year of a 5-year study 

 of the blackbird-corn damage problem in the vicin- 



ity of Sand Lake National Wildlife Refuge 

 was completed in September. As in previous 

 years, the program w;i> a cooperative under- 

 taking of the Bureau and the South Dakota De- 

 partment of Game, Fish, and Parks. 



The program in 1963 included (1) tests ol 

 fright-producing and soporific chemicals to protect 

 cornfields from foraging blackbirds, (2) tests oi 

 amplified bird distress calls broadcast from ground 

 equipment and low-flying aircraft, (3) banding 

 and color-marking blackbirds to determine breed- 

 ing and wintering areas, migration routes, and 

 extent of local movement. (4) appraisal of corn 

 losses in a 94-section area adjoining Sand Lake 

 Refuge, (5) evaluation of grain sorghums as pos- 

 sible blackbird-resistant crops, (6) precise esti- 

 mates of blackbird populations using Sand Lake 

 Refuge during the damage period, (7) food habits, 



Hoards of blackbirds or starlings feeding on grain or in feed lots cause heavy losses to owners. A flock of 10.000 

 blackbirds can consume 2 tons of grain per week, worth $60 to $160. In such instances, selective control of over- 

 abundant wild birds is justified. (I'hoto by Brooke Meanley) 



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