10 



CIRCULAR 15, FISH AND WILDLIFE SERVICE 



TICK CONTROL 



CAMP BULLIS. TEX. 



During the summer of 1947, the 

 vahie of DDT dust for tick control 

 was investigated in a large-scale 

 field experiment by the United 

 States Army and the United 

 States Department of Agricul- 

 ture. The treated area was a 

 206-acre plot at Camp Bullis, 

 Tex., within the Leon Springs 

 Military Reservation, about 18 

 miles northwest of San Antonio. 

 A mixture of 10-percent DDT in 

 pyrophyllite was applied to the 

 ground and vegetation by means 

 of two dry-fog orchard dusters. 

 The rate of application was 43.56 

 pounds of the dust mixture, or 

 4.36 pounds of DDT, to an acre. 

 The effects of the experiment on 

 wildlife were studied by members 

 of the Fish and Wildlife Service. 



Mammals 



Small mammals were too few in 

 numbers to carry on intensive 

 population studies by live-trap- 

 ping methods. Other larger, 

 wider-ranging species, although 

 plentiful, were not limited by 

 normal range to the 206-acre 

 treated plot, and so were not well 

 suited for study subjects. Never- 

 theless, intensive studies prior to 

 and after treatment showed that 

 the following species apparently 

 were unaffected or only slightly 

 affected by the DDT operations: 

 white-tailed deer, raccoon, striped 

 skunk, armadillo, jack rabbit, and 

 cottontail rabbit. 



Birds 



An abundant bird population 

 was studied by comparing popula- 

 tion trends in a 40-acre study plot 

 in the treated area with those in a 

 check area of similar size. An 

 intensive search was made for 

 mortalities. In all, 86 pairs of 

 adult birds, representing 33 spe- 

 cies, were recorded on the study 

 area. A comparable predusting 

 population of 90 pairs was found 

 on the check area. 



The first evidence of bird kill 

 was noted on the day after appli- 

 cation of the dust. From all indi- 

 cations deaths continued through 

 the fifth day. Fifteen dead birds 

 were found — 9 cardinals, 2 

 painted buntings, 2 lark spar- 

 rows, 1 yellow-breasted chat, and 

 1 white-eyed vireo. Because dense 

 ground cover in many places 

 made the recovery of poisoned 

 birds difficult, the true extent of 

 the kill is better indicated by the 

 decline in the census counts from 

 86 pairs before, to 39 pairs after, 

 dusting. The population in the 

 check plot dropped from 90 to 78 

 pairs during the same period. 

 The individuals found dead indi- 

 cated that the species primarily 

 affected were the ground and low- 

 strata feeders. Population rec- 

 ords for the 9 species of birds that 

 appeared to be most seriously af- 

 fected by application of DDT dust 

 are given in table 1. 



