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WATERFOWL BREEDING GROUND SURVEY IN DELAWARE - 1950 
E. B. Chamberlain 
Introduction 
So far as is known this is the first year that any attempt has been made to 
keep track of the waterfowl population throughout the breeding season in this State 
This study had three main objectives: 
1. To determine the peak and the duration of the spring migration. 
2. To determine the resident or breeding population. 
3. To determine total number of broods and average size of broods. 
The survey was started at the peak of spring migration, which this year was 
during the last week of March. All of the survey was done by the aerial transect 
method with the author acting as pilot and two other P-R men, Henry Cofer and 
Robert Beck, taking turns as observer. 
Transects were flown every week until it was evident that migration was 
over; then they were flown twice a month until the first week in September, when the 
semi-monthly aerial counts of total population were started, 
Methods Used In Sampling, And Area Covered 
As already stated, the aerial transect method was used exclusively. This 
method is too well known to need description here. However, it should be noted that 
after migration was over it was possible for both pilot and observer to record numbers 
by species. This is probably somewhat more accurate than applying the percentage of 
each species seen by the observer to the total counted by the pilot to obtain total 
numbers of each species. 
Seven transects were established. These have a combined length of 64 miles, 
and are laid out in such a manner that all the important waterfowl producing areas of 
the State are.covered. The location and length of each transect is shown on the 
accompanying map. While it may seem that these transects are rather short, they 
contain 16 square miles and constitute a 7.5 percent sample of the waterfowl habitat 
of the State. 
There is not much variation in habitat along any of the transects, Probably 
the greatest single variable is the gradual change, from north to south, in the salinity 
of the water. Transect No. 1, covering the Newport Marsh, is essentially fresh in 
character, while No. 7, running from Rehoboth to the Delaware-Maryland State line, 
covers water that has a salinity approaching that of the sea. Between these two lie all 
ranges of salinity. The most waterfowl were found in marshes where natural or man- 
made barriers have excluded the tide and the vegetation is mainly of the fresh water 
type. Fortunately, many of the marshes fall into this category. | 
Data Collected And Their Meaning 
Weather and Water Conditions 
Throughout the period the weather was essentially normal. Precipitation 
was very nearly average every month until August when it fell a bit below the average 
for that month. Water conditions in marshes and potholes were generally favorable. 
Temperatures were slightly below normal and the growing season was about two weeks 
later than usual. 
