to 1. 88 ppm ) . and a trace of aldrin were also found 

 in several of tlie specimens. The findings further 

 illustrate the almost universal presence in fish and 

 wildlife of certain widely used, persistent chlori- 

 nated-hydrocarbon insecticides. 



Prairie grouse-fesstiddeii investigation. — The 

 acute toxicity of insecticides to wild grouse was 

 studied by the Denver Center in a cooperative proj- 

 ect with Montana Game Department personnel. 

 Male sliarptails were trapped on the breeding 

 grounds, marked, and released after each had been 

 given a single oral dose of dieldrin, malathion, or 

 sugar in capsules. Reactions of the test birds were 

 determined by observing them on or near the 

 breeding grounds after treatment. 



Of the 52 test grouse. 40 were marked with num- 

 bered neck tags legible from a distance with a 

 spotting scope, and 12 were equipped with micro- 

 radio transmitters. Several carcasses were re- 

 covered in this manner, and other information 

 was obtained, such as observations on behavior 



and symptoms of sick birds. Daily activity and 

 movements were telemetered in individual birds. 



The LDso for dieldrin in wild grouse was 6.9 

 mg/kg (4.4 to 10.9, ;^=0.05). This was very 

 similar to an LDjo of 6.4 mg kg (3.3 to 12.5. 

 />=0.05) obtained with captive male sharp-tailed 

 grouse. Malathion was much less toxic than diel- 

 drin to the grouse. Individual birds differed in 

 resistance, but the critical dose appeared to lie be- 

 tween 200 and 250 mg 'kg. Results of malathion 

 tests with captive male grouse were similar. In 

 21 tests, 13 penned birds dosed with malathion 

 below 200 mgAg survived and 1 dosed above 220 

 mg/kg died. 



Pelicans and pesticides. — A variety of tech- 

 niques are being used by the Denver Center to 

 evaluate effects of pesticides on the dynamics of 

 white pelican populations. These birds are ap- 

 parently rather continuously exposed to certain 

 insecticides in fish, since pelicans often feed in 

 areas receiving waste agricultural water. Fish 



The relation of pesticides to the downward trend in eagle populations is being studied intensively by the Bureau. 

 Experimental birds are held in suitable pens or houses where controlled studies permit a high degree of accuracy 

 in results. Young golden eagles (left) and young bald eagle i right). (Photois by Frederick C. Schmid) 



