Breeding Pepalation Trends 
The data for Table I was furnished for this report by the Missouri River 
Basin Studies, Grand Island Office. The transects follow the Valentine-Thedford 
Highway for the ground count and follow and parallel it for the aerial counts. Three 
observers made the 1952 ground counts as compared to one observer for the 1951 
counts, 
Table I - Central Sandhills Transects, Air and Ground 
SR a a TD pre aa pe EE 

Aerial Count * Ground Count ** 
Date Ducks per Square Mile Date Ducks 78q. Mile Pairs 7Sq. Mile 
5/24/49 6.8 
5/24/50 . 8.3 
5/18/51 7.5 5/14/51 12.1 3.1 
5/20/52 7.7 5/20/52 30.3, 11.2 
Percent Change +16 + 150 + 261 

* 1952 count by W. Sweeney and R. Goodman 
** 1952 count by W.. Sweeney and G. Larson 
Table II = Western and Eastern Sandhill Ground Transects* 


Western Eastern Over-all 
Routes Routes Routes 
Square miles sampled 33.1 8.2 41.3 
Ducks in Sample 4, 093 152 1,245 
Ducks per square mile 33.0 18.5 30.1 
Pairs sampled ** 671 112 783 
Pairs per square mile _ 20.3 13.7 18.9 
‘Percent change from 1951 : 
‘Ducks per square mile ~ 4.1 (ooded trails prevented 
Pairs per square mile - 4.2 1951 counts) 

* Counts made June 9, 10, and 11, 1952 
** Actual pairs plus territorial drakes 
The decrease in breeding population shown in Table II may be due to the 
advancement of the 1952 season over that of 1951. The hatching dates and other 
phenology were from one to two weeks earlier than those of 1951. Using this and 
the average daily decline in apparent breeding numbers, this loss is offset; in any 
event, the decrease is insignificant. 
This same seasonal advancement may be the cause of the much greater 
increase in pairs per square mile as related to ducks per square mile as shown 
in Table I. All observers noted the increase in territorial activity at the time of 
breeding population counts. 
