Mallard duck behavior question

I apologize that my pictures are from an iPhone. Saw this duck/ducklings at a pond at a local park in WI. Only other duck anywhere to be seen was the mate of this female mallard. 21 ducklings which I initially thought were all the same size, but when they got out of the water I could tell 6 of the 21 were a little bigger. So it seems this is a least two hatches if not three. I can't come up with a logical explanation and am looking for other people's thoughts.

I believe some species of Anatidae form creches of the young, for two reasons. Firstly, there is safety in numbers - a large number of targets confuses any predators, and secondly the adults can swap around so they can each feed without having to watch the young as they do so. This may be what is happening here. Nice pics, anyway.

Tony,

When I read your comment, I was actually reminded of another unusual thing we saw the same day that makes your hypothesis very plausible.

This pond is actually part of a park that has a small, maybe 30-40 acres, outdoor zoo. We drove past the pond on the left and saw the above pictures. Then about three hundred yards further up the road we saw a bald eagle sitting in a dirt field off to the right being pestered by red winged blackbirds. We don't see eagles here very often because we have no major bodies of water. I'm just wondering if that eagle could have been flying over the pond looking for lunch and created the above response. It's always great to learn new information about wildlife behavior. Thanks.

Hi Rod,

Around here eagles and ducks/geese share the same bodies of water. I've seen a Bald Eagle go after ducklings. Here's a photo of a gosling being snatched. On this particular body of water the only thing that makes every bird on the water scatter is the arrival of an eagle. They all settle down, but it's it's impressive. Most often the eagles are after the carp, but ducklings and goslings seem to be the waterfoul du jour when they are present. Maybe that sort of scenario plays out in your location.

ok, now the image.

I think there is a military channel Combat 360. Danger comes to the Enterprise aircraft carrier from 360 degrees, above the water, air planes, on the water ships and below the water submarines. The pond behind my house has a dozen turtles that swim under water for some time. One is 2 feet in diameter. I think a duckling would make a nice dinner for him with some fava beans and a good chianti. I expect that's why they group together with momma who might offer some deterrence. Also, I wonder if bunched up they look like one big creature, a threat to the predator.

The grouping together is standard mallard procedure for moving from one feeding area to another. If there's a threat, they'll haul ass, literally, to cover and not stay out in the middle of a pond.

 

Mallards, like many bird species, will have a second clutch if they lose their first clutch. Spring flooding gets a lot of waterbird nests. I've seen it when there's been a total loss, but I'm surprised to see a clutch with two age groups. They do grow fast, so some may just be a couple of days older than the others. Maybe there was some interruption that caused them not to hatch all at once.

 

My informal observation says that over half the duckling don't make it to adulthood. They're bite-sized treats for great blue heron, snakes, raccoons, etc.