10 



Live Birds Seen 

 Miles Robins Meadowlarks 



Date Area Traversed Totaltper mile Totaltper mile 



March 7 Heptachlor 2.6 



March 8 Heptachlor 2.0 



March 9 Dieldrin 1.5 



March 8 Check 2.1 



Studies in Texas [39] and Louisiana (Glasgow, letter), where populations 

 had declined over 85% soon after treatment and nesting success was reduced 893= 

 or more, indicated the effects on songbirds during the second year to be de- 

 pressed populations rather than nesting success. Populations were about 11% to 

 70% normal depending on the species and habitat group, and census method, but 

 nesting success appeared to be almost normal for the population present. Nest- 

 ing success in these studies is judged by percent of nests in which young were 

 fledged. No data are available on fledgling survival in the field. Studies of 

 this phenomenon are continuing. 



c. Effects on Bobwhite Quail . This species has received special study 

 and several investigations in at least 3 States give quantitative findings which 

 enable rather precise predictions of the fate of quail on treated areas. In 

 general, the bobwhite reflects the strata and area effects described earlier 

 for songbirds, i.e., virtual elimination on treated areas with gradual repopu- 

 lation during the first year after treatment but with some mortality and with 

 depressed populations persisting into the second year. Also, individuals and/or 

 coveys can survive on small untreated tracts within large treatment blocks. 

 Third year effects will not be available in any area until the summer of 1960. 



At the Alabama Polytechnic Institute Substation in Wilcox County, the 

 Bureau's Alabama Unit Leader, Baker, and others [2] gathered the information 

 presented in Table 14. It is evident that the quail on treated areas were 

 virtually eliminated, with only a few peripheral birds (living largely off the 

 treated area) surviving. Populations continued to be seriously depressed (by 

 at least 35%) into the second year after treatment. Some die-offs continued 

 into the spring of the second year and analysis of tissue of dead birds revealed 

 appreciable amounts of insecticide. Populations appear to be approaching nor- 

 mal at the end of the second year (Baker, et al., unpubl.). 



Studies by the Bureau [49] in Decatur County, Georgia, of treated and un- 

 treated areas are presented in Table 15. Populations of whistling cocks a year 

 after treatment continued to be depressed by over 50% (Rosene, unpubl.). This 

 is higher than the Wilcox County area and can be explained by the size and 

 shape of the study areas. Baker's Alabama studies were on a long linear unit 

 of about 3600 acres, and repopulation was more rapid from the surrounding un- 

 treated lands than on the extensive 10,000-acre plots Rosene studied in the 

 heart of the extensive treatment blocks (approximately 100,000 acres) in 

 Decatur County, Georgia. Probably, also, this explains why the number of coveys 

 in the treated areas in Georgia continued to be depressed greatly during the 

 first and second winters after treatment. Rosene' s studies also show that quail 

 can survive on small tracts of untreated land within big treatment blocks. On 



