We have a special bonus today: DUCKS AND DUCKLINGS! At my request, UC Davis ecologist Susan Harrison took photos and video for this site when she went out yesterday to help a colleague band, chip, measure, and DNA-sample wood ducklings.  Susan’s narrative is indented; click the photos to enlarge them.

Notes From a Wood Duck Research Field Trip

In early June 2023, I accompanied UC Davis’ John Eadie, a leading expert on waterfowl biology and conservation, to measure and tag newly hatched Wood Duck (Aix sponsa) ducklings.

For ten years, John and his collaborators have been studying the social lives of Wood Ducks, especially the striking behavior called nest parasitism. Females (‘hens’) may lay some or all of their eggs in the nests of other Wood Duck hens.  Why do they do this?  It’s probably related to the fact that they nest in tree cavities, which are a scarce resource. But how do hens decide whether and whom to parasitize?  What determines the shifting benefits of raising your own kids versus trying to get them raised by someone else?   You can read this lively and beautifully illustrated American Scientist article to find out what’s been learned and what’s still unknown.

We went to a private ranch near Davis where John and his lab have set up 100 of their 400 total nest boxes.  Nest boxes help boost Wood Duck populations, and when suitably equipped, they also make it easy to collect data on hens and ducklings.

These ‘research’ nest boxes can be raised or lowered for access, and are equipped with instruments that read the output from tiny radio tags similar to pet microchips:

The first step is to lower and open the nest box to see if the eggs have hatched:

Then the entrance hole is covered to keep the hen inside and the ducklings are carefully extracted:

Each duckling is brought to a mini-lab on the truck tailgate:

Being a good mentor, John is letting me ‘help;’ here I’m holding my first duckling:

Ducklings are slid headfirst into the tube to be weighed:

Bill length, bill width, and tarsus length are measured:

A tiny pinprick allows blood to be drawn for DNA analysis:

A radio tag the size of a rice grain is gently and safely slid under the skin:

Foot color is recorded as tan (left), orange (right), or pure black, since John is curious about this variable trait:

Ducklings then go back to their nest and the seemingly calm hen.   Using this combination of radiotagging and DNA, John and collaborators have collected around 3 million data points, each one a combination of an individual duck’s identity, parentage and location. These data have shown, for example, that a hen’s tendency to parasitize is pretty strongly correlated with her mother’s tendency to parasitize.

We stopped at John’s aviary on campus.   Here I’m holding Konnie, a Wood Duck hen who was hand-reared and named for Konrad Lorenz, to show off her gorgeous iridescent wings:

In this brief video, Konnie and her mate Crookneck like they are eating but they are actually performing a contact ritual, watched by a Mallard (Anas platyrhynchos).  Turn the sound up to hear their squeaky calls and John explaining their behavior.  He says many pair-bonding behaviors in birds are ritualized versions of feeding: (Photo 13)

This male Cinnamon Teal (Spatula cyanoptera), less friendly than Connie, energetically nibbled at fingers when picked up:

It was great fun comparing notes with John about research. When I was in grad school learning plant and insect ecology, it was often said that you couldn’t really test theory using birds or wildlife, because you couldn’t do experiments or get large amounts of data.  But sensor and DNA technologies have since transformed the study of animals in the wild. And with Wood Ducks, a researcher can deploy their most critical resource – nest boxes – and return later to find abundant and accessible study animals.  However, since adult male Wood Ducks are hard to catch and tag, their role in the social network is not yet well understood.