Welcome to Frank's Field Notes, a semi-regular look at what’s happening across the Prairie Pothole Region during spring migration and breeding season.

Part field journal, part migration report, and part window into duck country, Delta Waterfowl Chief Scientist and President Dr. Frank Rohwer offers firsthand observations from the field on ducks, geese, weather, habitat conditions, and the annual return north.

Swan Identification

5/12/2026

How to tell a Trumpeter Swan from a Tundra Swan

Ruddy Duck Video

5/11/2026

This video shows the most frequent display by male ruddies to impress females.

Three Pairs of Teal on the Road - It must be the p...

5/10/2026

Females searching for an upland nesting site like to land in an open spot that has no predators.

Timing of Pair Counts

5/9/2026

We believe the best timing is when there is a 1:1 ratio of paired birds and lone males, which we assume have a hen that is on a nest.

Drying Fast in Bismarck

5/8/2026

When seasonals and temporary ponds hold water into summer the prairies really hold ducks. This year is better than last, but not great.

Prairie Arrival Order Does not Match Nesting Dates

5/7/2026

Check out these timelines of arrival and nesting dates.

Last to Arrive - Different Breeding Strategy

5/6/2026

The typical last duck to get to the prairies arrived at Bismarck about a week ago.

Some Individuals Pair Late

5/4/2026

Unlike most birds, ducks form pair bonds in the winter – many months before nesting.

Redefining Spring

5/3/2026

First hatch was just a few days ago. In my opinion that should be the definition of spring, not daylength.

Black-bellied Whistling Ducks

5/2/2026

Louisiana is set to start a special short season on them in October 2026.

Boxes Increase Parasitism

5/1/2026

Laying parasitic eggs is not a response to nest shortage, but a strategy to increase Darwinian fitness – the number of genes (kids) in the next generation.

Are nest sites in short supply, making parasitism ...

4/30/2026

Absolutely not! But that is a common explanation for females laying parasitically.

drawings of difference between waterfowl and other birds

Nest Parasitism - Common in Ducks and Other Precoc...

4/29/2026

In ducks, extra eggs have far less detrimental impact as young feed themselves.

Parasitism - An Alternative Reproductive Strategy

4/28/2026

Laying parasitic eggs is a common reproductive strategy in ducks.

Individual Identification - Nasal Saddles

4/27/2026

The saddle is secured on the duck’s bill by a thin rod that goes through the existing nose holes in the bill.

Unusual biology of Whistling Ducks

4/26/2026

Males help care for ducklings, which is unlike the great majority of worldwide ducks, but not geese and swans.

Unusual Nest of Black-bellied Whistling Ducks

4/25/2026

My brother and I had a great day on the water in Cameron Parish, Louisiana. The highlight was finding multiple Black-bellied nests on small islands in Lake Calcasieu.

Iconic Louisiana - Good and Bad

4/24/2026

GOOD: The phenomenal expansion of Black-bellied Whistling-Ducks – both in range and population size - over the past 40 years.

Big Males

4/23/2026

Muscovy and Mallards are the two ducks that have repeatedly been domesticated.

Not in Kansas Anymore

4/22/2026

I started the day with meetings and talks at Louisiana State University, but during a midmorning break I was delighted to see this hen at a campus lake with 6 ducklings that are about 10 days old.