Contents 
PC ETSCE. «cay ites ee ties sy 
ve a a Saat 8 -. iv 
LAEPORUGGTG. sack seca eee we oy BA ee eee + ta 
Singing-Ground Survey ..... sass mH, RE ere ree ps wale 
Source of data ........ oe £6 Ase AUER a we ee 
Method of analysis ........... Pre dasas ae So re 2 
Weighting factors ......... er eS ee ee 
Resulte wctvee views ede ee eee Fh Seats Oe 5 ees 
Effects of freezing weather in Louisiana ....... 5 
Recommendations to cooperators ..... pet et eee ee i 
Random sampling in Michigan .......... isl aS ate AR a 
Wing-Collection Survey .....ccencccusscene AW ee eve 
Bouree OF Wings: <2... cwnneenwnsckas duce walk ee Ye 9 
Age and sex determination ............ oi - 9 
Method of analysis ........ seam ak eae we fe Be Pe oe 1G 
Weighting factors ....-..e.e00. ‘ oe ee é - LO 
Results «sss ecacsvas Beem, wri hee ra Scher 1 a bee de Chk 
Acknowledgements .....sesecevere ‘ iia sure gear serk ye eles 
iii 
