with more than 40 live coyotes were terminated. 

 The objective was to determine tlie acceptance, 

 tolerance, and effects on reproduction of diethyl- 

 stilbestrol, an orally administered, synthetic estro- 

 gen. Pen trials showed good acceptance of the 

 drug both in tablet form and when dissolved in 

 lard. 



Experiments in the inhibition of reproduction in 

 coyotes by lilocking ovulation were inconclusive 

 since neither the treated nor control animals came 

 into estrus during the normal period. A degree 

 of success was attained in terminating pregnancy : 

 there were several instances of resorbtion of em- 

 bryos following administration of stilbestrol. 

 Ten additional holding pens and a new feed build- 

 ing were constructed in preparation for more ex- 

 tensive tests during the winter of 1963. 



PESTICIDE-WILDLIFE RELATIONS 



The controversial pesticide question finds the 

 Bureau in the responsible position of seeking facts 

 on the immediate and long-term effects of pesticide 

 use in the wildlife field. Its several investiga- 

 tional programs are to the end of pesticide use 

 with the greatest possible safety to man and wild- 

 life; and, in the Bureau's concept, safe use requires 

 a multiple approach in research : more selective 

 chemicals, more acurate dosage, substitution, where 

 feasible, of biological or ecological methods for 

 chemicals, less toxic but still effective chemicals, 

 rigid adherence to prescribed direction, and. al)0ve 

 all, thorough testing prior to release for general 

 application. 



Pesticide-quail studies at Putiixent. — Eesults of 

 preliminary tests indicated that zytron is moder- 

 ately- toxic to adult quail, but that the other 

 herbicides tested have relatively low orders of 

 toxicity. No effects on survival or body weight 

 were found in trials with amiben. casoron, tiphena- 

 mid, and diphenatrile: however, effects of these 

 compounds on quail reproduction have not been 

 determined. Amitrole, amitrole-T, dacthal, dal- 

 apon, MCPA, and chlorinated phenoxy herbicides 

 also had slight effects upon growth and survival, 

 but sublethal exposure to these compounds had 

 marked inhibitory effects upon reproduction. 

 Quanities producing inhibitory effects ranged 

 from less than 10 to approximately 5(1 ])ercent of 

 the estimated lethal dose. 



Similar inhibitory effects on reproduction re- 

 sulted from feeding diets containinir TiO or lOd 



p.]).m. of kepone before and during the breeding- 

 season. The lack of rei:)roductive success thus 

 induced was acompanied by changes in feather 

 pigmentation of males, wherein the plumage of 

 male quail resembled that of adult females, and 

 male pheasants and ducks did not exhibit the usual 

 characteristic coloration. Mirex, which is closely 

 related to kepone, is less toxic and did not have 

 any apparent effects on reproduction or secondary 

 sex characteristics. 



Data f I'om these feeding tests were supplemented 

 by studies in which birds were confined in areas 

 which had been treated with heptaclilor in ac- 

 cordance with accepted insect -conti'ol practices. 

 Thirty-two covered pens, each 20 by 50 feet, were 

 constructed for the tests; eight remained untreated, 

 and the others were treated with granular 

 heptaclilor at the rates of 2.0 (6 pens), 1.25 (6 

 pens), and 0.25 (12 pens) pounds per acr-e. One 

 pair of adult, pen-reared bobwhite quails was 

 placed in each pen immediately after application 

 of the insecticide. "^AHien mortality occurred in 

 any pen, the surviving member of the pair was 

 sacrificed and a new pair was used in replacement. 



Mortality occurred in 20 of the 22 pairs placed 

 in pens treated with 2.0 pounds to the acre, and 

 the survival times for these birds were approxi- 

 mately equal to those of birds fed diets containing 

 100 or 200 p.p.m. of heptachlor. The two surviv- 

 ing hens produced a total of seven chicks. Six- 

 teen pairs were started in pens treated with 1.25 



%. 



Biologist dipping for mosquito larvae in impoundment 

 at the Patuxent Wildlife Research Center. The main 

 objective of this research is the development of speci- 

 fications for impoundments suitable for wildlife use but 

 relatively nonproductive of this insect pest. (Photo 

 by F. C. Schmid) 



45 



