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.

various birds photographed by Frank Rohwer

Great Delta Marsh Weekend

6/22/2026

The weekend at Delta Marsh allowed viewing of lots of ducks, but the diversity of other birds was also impressive.

How to Estimate the Stage of a Nest

6/22/2026

Candling means we look at the developing duckling inside the egg. This technique is decades old.a

Migration to Molt Feathers, not to Escape Cold

6/20/2026

Jim Fisher’s photo shows the lush green of the Manitoba countryside, which makes clear that this is a mid-summer movement.

Low snow winters - bad for ducks; good for pheasan...

6/19/2026

Yesterday I was the bearer of bad news about dry habitat and reduced duck numbers in North Dakota.

A Double Dose of Poor News

6/18/2026

Pilot/biologist field notes that simply describe what the federal crews saw when conducting the larger May surveys were released today (no data until August).

Young Ducklings are Vulnerable

6/17/2026

Every brood study shows that the majority of duckling mortality happens when ducklings are less than 10 days old.

A Dichromatic Hawk

6/16/2026

Dichromatic is our jargon for two colors – as in many male and female birds.

Let's Celebrate our Wildlife Thinking, but Acknowl...

6/16/2026

Why they do what they do? Those are – in my opinion – the most interesting questions about wildlife.

About to Depart

6/14/2026

Male Canvasbacks depart for molting areas earlier than most other male ducks.

Almost as cool as duck nests

6/13/2026

Phalarope nests are serious contenders for 2nd coolest nests on the prairies (ducks obviously #1).

Great Picture from New Member of Research Team

6/13/2026

We are very excited that Charlee Manguso has joined the research team.

They Won't Follow Mom into the Pond

6/12/2026

For dabbling ducks, it is too dangerous to walk in the grass to find a host nest.

Delta Marsh Midges

6/10/2026

Midge larvae are the engine that drives the great productivity of ducks and other birds at the Delta Marsh.

Marked Hen

6/9/2026

You might be able to see the black antenna over her tail. This poor girl lost her nest, so we may soon get location data from a molt migrations site.

Hooded Merganser Parasitism

6/8/2026

Todd got this picture of a Hooded Merganser in Bismarck that had 15 ducklings (2 not in pic) - surely a result of nest parasitism. Another Hoody laid some eggs in this girl’s nest.

Widespread Waterfowl

6/7/2026

Whistling ducks were previously named tree ducks, but Fulvous rarely perch in trees. In the US they often nest in rice fields.

Beautiful Relatives of Our Blue-wings

6/6/2026

Silver teal (Spatula versicolor) are cousins to our blue-winged ducks – Shovelers, Cinnamons and Blue-wings. All in the genus Spatula – clearly named for that Shoveler bill.

Ringed Teal in Argentina

6/5/2026

Ringed Teal are interesting because they nest in tree cavities in the subtropics or they use old stick nests of colonial Monk Parakeets (bottom 2 pictures).

The Mallards - Most Popular Duck - of Argentina

6/4/2026

Rosy-billed Pochards are the iconic duck of much of Argentina and highly sought after - much like Mallards are in North America.

Spring Snow/Ross's Season Closed at the End of May

6/2/2026

Yearling Snow Geese (left bird with some grey feathers) never breed, so there is no rush to get to arctic breeding areas.

Yippee - rain!

5/31/2026

We have been dry, so seeing those clouds to west and rain falling to the east is magic.

Philopatry to Nest Sites

5/31/2026

Female waterfowl show breeding philopatry. That is jargon for homing to the area where they were raised or settled last year.

Cells Phones are Amazing

5/30/2026

While not delicious, mergansers are certainly beautiful and cool ducks.

Fisher Photographs a Hen Moving her Eggs

5/28/2026

This late nesting Canada Goose is billing the eggs in the top photo, then she settles down again.

Yesterday's Milestone - First Marked Canvasback of...

5/27/2026

This hen is a couple of days from being the first hen of close to 170 nesting Cans to hatch her clutch.

Robins Clean; Ducks Mostly Don't

5/27/2026

This hatched Robin egg (about ½ inch in width) was in my yard today. It reminded me that most birds take egg shells and other trash away from their nest.