October led Delaware's Canada goose counts during the survey's first years. The state's aerial counts of waterfowl reveal how far the seasonal pattern has shifted. We examined two periods covering about fifteen years apiece. The earlier period spans 1974 to 1989. The later period covers 2010 to 2026. Every figure below gives the mean bird count for each zone row. A row represents a single survey zone during a single flight.
IA different seasonal pattern
Winter now brings Delaware's highest goose counts
Canada geese reached their earlier high in October with an average of 11,009 birds for each zone row. The newer October average was 1,713. That represents an 84 percent decline. January became the leading month with 3,284.
Snow goose counts increased as their busiest month shifted later. November led the earlier period with 2,315. December leads the newer period with 15,470. That December count is about 11 times its earlier counterpart of 1,353.
Swipe table to see every column
| Species | Era | October | November | December | January |
|---|---|---|---|---|---|
| American black duck | Early (1974 to 1989) | 683 | 835 | 1,295 | 1,205 |
| American black duck | Late (2010 to 2026) | 529 | 1,010 | 1,231 | 984 |
| Mallard | Early (1974 to 1989) | 481 | 592 | 1,186 | 975 |
| Mallard | Late (2010 to 2026) | 500 | 1,092 | 1,453 | 1,076 |
| Green-winged teal | Early (1974 to 1989) | 1,146 | 877 | 211 | 54 |
| Green-winged teal | Late (2010 to 2026) | 1,059 | 809 | 485 | 155 |
| Northern pintail | Early (1974 to 1989) | 491 | 349 | 228 | 79 |
| Northern pintail | Late (2010 to 2026) | 699 | 355 | 197 | 146 |
| Gadwall | Early (1974 to 1989) | 97 | 105 | 99 | 31 |
| Gadwall | Late (2010 to 2026) | 106 | 286 | 395 | 189 |
| American wigeon | Early (1974 to 1989) | 97 | 58 | 46 | 21 |
| American wigeon | Late (2010 to 2026) | 87 | 40 | 32 | 32 |
| Northern shoveler | Early (1974 to 1989) | 54 | 82 | 49 | 22 |
| Northern shoveler | Late (2010 to 2026) | 134 | 183 | 178 | 85 |
| Canada goose | Early (1974 to 1989) | 11,009 | 4,599 | 4,759 | 4,979 |
| Canada goose | Late (2010 to 2026) | 1,713 | 2,135 | 2,886 | 3,284 |
| Snow goose | Early (1974 to 1989) | 1,997 | 2,315 | 1,353 | 587 |
| Snow goose | Late (2010 to 2026) | 981 | 3,271 | 15,470 | 9,333 |
IIChanges among ducks
Mallard counts rose while black duck counts fell
Ducks showed smaller changes than geese. Mallard counts increased. Their November mean climbed from 592 to 1,092. That amounts to an 84 percent gain. December's earlier mean was 1,186. It later reached 1,453. January's average increased from 975 to 1,076. December remained the leading month for mallards in each period.
American black ducks likewise continue to reach their high in December. The earlier period averaged 1,295 that month. The newer period averaged 1,231. Their January average dropped from 1,205 to 984. That is an 18 percent decline. October's black duck average decreased from 683 to 529.
Most counts for the smaller dabbling ducks increased. October remains the top month for green-winged teal. Counts in later months are now higher. December's average increased from 211 to 485. January's mean rose from 54 to 155. Gadwall's busiest month changed from November to December. Their January average increased from 31 to 189. Northern shoveler counts increased across all months. October pintail averages climbed from 491 to 699. Their January averages increased from 79 to 146. Among these ducks only American wigeon declined during most months. Their October mean dropped from 97 to 87. December's average fell from 46 to 32.
Swipe table to see every column
| Species | Early (1974 to 1989) | Late (2010 to 2026) | Change, percent |
|---|---|---|---|
| American black duck | 1,205 | 984 | −18% |
| Mallard | 975 | 1,076 | +10% |
| Green-winged teal | 54 | 155 | +187% |
| Northern pintail | 79 | 146 | +85% |
| Gadwall | 31 | 189 | +510% |
| American wigeon | 21 | 32 | +52% |
| Northern shoveler | 22 | 85 | +286% |
| Canada goose | 4,979 | 3,284 | −34% |
| Snow goose | 587 | 9,333 | +1,490% |
IIIWhy compare longer periods
Five surveys from the 1970s make the apparent decline larger
Grouping the results by decade begins with the late 1970s. That first decade includes just 5 January surveys. Taking those five flights as the reference puts January mallards 41 percent lower during the 2020s. Black ducks appear 45 percent lower on the same basis. Such a small starting sample provides a thin basis for comparison. The combined average for those five January surveys was well above the average for the full 1974 to 1989 period. Using fifteen or more survey years for both periods instead yields a January mallard increase of 10 percent and a black duck decrease of 18 percent. Our main comparison uses the longer periods because they draw on many more flights. No individual baseline is the uniquely true one.
The periods also differ in their survey coverage. Each month in the earlier period has 15 or 16 surveys. The newer period includes 17 surveys for January. Its November count is only 11 and its October count is 13. As a result the newer fall figures rely on fewer flights than the winter figures.
IVLimits of these tallies
Sightings do not equal all birds present
Each zone row documents a single flight's observations within a single survey zone. Its count records the birds observers saw. It estimates neither population size nor the number of birds per acre. Weather, ice and the timing of a survey all affect what the crew can see. A bird recorded in Delaware may appear in a count elsewhere during a different month. Delaware's figures do not represent totals for the Atlantic Flyway. Additional species appear in the survey beyond those included here. They include brant, scoters and bufflehead.
These totals provide no explanation for the changes. Neither the October goose decrease nor the December snow goose increase is given a cause here. We likewise assign none to the higher November mallard count. Three rows lacked a zone and were excluded. Source records use two spellings for November. Both were grouped under November in our count. For the duck timing question see our guide to when dabblers and mallards leave in relation to cold and snow. It addresses departures as a separate issue from the totals examined here.
VWhat we take from this
Aim Delaware goose plans toward midwinter
In our view a Delaware hunter using the former seasonal calendar is relying on counts whose peaks have since shifted to other months. October's Canada goose count is now only a fraction of its earlier level. December and January therefore bring today's best Canada goose numbers. Snow goose counts surge during December. November now has far higher mallard counts than before. December continues to lead for both mallards and black ducks. We base our expectations on the records covering 2010 to 2026. Stories about the 1970s belong to a different seasonal pattern.
NOTES AND SOURCES
- Source: Delaware Division of Fish and Wildlife aerial waterfowl survey, Delaware Open Data.
- Scope: 601 January zone rows from 52 January surveys, 1975 to 2026, 12 survey zones.
- Cleaning and exclusions: 3 rows with no zone held out. Months other than January are not used for the decade comparison.
- Method: Mean count per zone row (DERIVED). A zone row is one survey zone on one flight. It is birds seen, not a population estimate or birds per acre. Main comparison is two eras of about 15 years each, early 1974 to 1989 and late 2010 to 2026, because the 1970s alone hold only 5 January surveys and swing the decade comparison.
Fully Drawn Research is an independent data analysis desk, not affiliated with any state wildlife agency, transportation agency, mapping provider or outfitter. Fully Drawn Research is an independent data and analysis desk. This paper reports FDR's analysis of public data. Harvest figures describe animals reported or estimated as harvested, not population size, and reflect hunter effort and regulations as well as animal numbers.
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