Monday, December 14, 2015

Wood Ducks

A Wood Duck drake

     Wood Ducks (Aix sponsa) are arguably the most beautiful ducks in North America. They have a variety of common names that are sometimes used for them. The colonists used to call them Summer Ducks, while regionally they are sometimes still referred to as Carolina Ducks, Swamp Ducks, Acorn Ducks, or just called Woodies. Their scientific name "Aix" comes the Greek for "waterfowl" while "sponsa" refers to "betrothed" or "beautiful bride" in Latin due to the beauty of the species. It is the only member of this Genus in North America (the only other Aix is the Mandarin Duck of Asia, Aix galericulata). Being a true all-American and handsome duck, it should surprise no one that it once was a candidate for our national symbol.

A pair of Wood Ducks, hen in front.

     Wood Ducks are now one of the most common ducks throughout North America, perhaps the third most common on the Eastern coast. But that was not always the case. By the early 1900's, Woodies were in serious danger of extinction due to market hunting for their meat and fine feathers (a staple on ladies' hats and fly tying), as well as destruction of wooded swamp habitats and especially the old trees with cavities needed for nesting.

Wood Duck feathers were popular for such things as ladies' hats and fly tying.

     By 1918 however, the Migratory Bird Act was passed and all waterfowl received protection. Thanks to the advent of nest boxes that conservation and hunting groups put up for them to nest in, Wood Ducks have made a remarkable recovery. This was probably helped along with the resurgence of beavers with the wooded ponds they construct and which these ducks prefer. They still benefit of course from such fees as hunting licenses (including the mandatory Migratory Bird Stamps and such needed prior to hunting) and the tax on all hunting related equipment such as lead-free ammo. Their greatest threat now, as for any waterfowl, is the need for wetland habitats.
     As mentioned, these are cavity nesting ducks. They normally use dead trees (snags) with large cavities in them. But they readily use man-made nest boxes as well. The female usually chooses the nest site (which may be used over and over again if they're successful) and she does little more than pluck a few feathers to place inside the hole. Hens lays 7-15 eggs which are incubated for about a month. Wood Ducks are the only ducks in North America that commonly nest twice in a single season.

A Wood Duck nest box. This one has predator guards to help prevent animals such as raccoons  from raiding them.

     Wood Ducks are well known for egg dumping. This is when a hen lays her eggs into another wood duck's nest. This seems to occur more with inexperienced first year birds, but can also happen when there are not enough nest sites available. Interestingly, it can also happen when nest boxes are too close to each other as well, regardless of how many nesting cavities or boxes are available. Normally nests containing more than 15 eggs are assumed to be dump nests. These have a much less chance of successful incubation and up to 30 eggs can be dumped in one single nest.
     Once the precocious young are born, they all remain inside the nest-hole for about a day. After that, they all climb up from inside the tree trunk or box using their claws and hooked beak-tips (features few other ducks have) and simply jump out. Their mom only helps by calling for them from below. They can fall upwards of 30' although 8'-10' is more typical. The young cannot fly of course, but seem to just bounce off the ground or into the water, little worse for wear regardless of the height fallen.
     Twice I've been lucky enough to catch this remarkable event, which rarely lasts more than 5 minutes once the first chick free falls. Once when I was fishing along the Shenandoah as a teen, I heard a Wood Duck hen calling. When I turned to look, I just caught the last two chicks plummeting into the river and being led away. It truly was a wonderful experience.

A Wood Duck hen leads her chicks at dusk.

     The second time was a bit stranger. I actually was at the National Zoo when a group of people in addition to myself saw several little ducklings emerge from a nesting box they had in one of their open air pens. However, the second to the last chick actually got its foot caught (maybe because of its long hooked claws?) in some screen that was on a little ramp by the nesting box leading into the water. The little guy looked to be in trouble and was half submerged, though its head was above the water. After realizing it was stuck, I hopped the fence and quickly tried to free it. Frankly, it was practically free already by the time I got there. Unfortunately for me, that was the exact moment a zoo keeper walked by. He was a bit upset that I was in the pen... Thankfully the rest of the people that were there explained my good intentions and the zoo keeper was nice enough to not cause me any trouble.

     Here's a short video of some woodie ducklings following their mother:     

These are juvenile Woodies, haven't quite gotten all their beautiful plumage yet.

     Woodies eat a variety of different foods, but are for the most part herbivores. As their name of Acorn Duck implies, they heavily favor acorns and other nuts, swallowing them whole. But they eat a great variety of other seeds too. I've witnessed flocks of 30 or so dropping into cut cornfields at dusk to glean spilled corn for example. Woodies seem to like duck weed as well. When young in particular, they will feed on insects and other invertebrates. Some stomach sample studies reveal what appears to be quite a preference for spiders as well. They seem to dislike shellfish and mollusks though. Wood Ducks themselves are considered good eating, some think due to their herbivore diet.
     Here's a short video of a pair on a duckweed-covered pond from the Capital Naturalist YouTube Channel:

     Wood Ducks are fairly swift and agile fliers. Some have timed them flying up to 47 miles per hour. I've always marveled at their agility when flying through flooded timber, even in very dark conditions. Their eyes (which are a striking red on the drakes (males)) are proportionally the largest of any of our ducks in size, perhaps helping them see in dim light. They are also quite fast on their feet. I've seen males chasing females, especially around March in our region, on merry foot-chases through the woods, sometimes oblivious to my presence in their ardor to get the female.
     The vast majority of Wood Ducks are gone for now, most migrating out of the DC area by November or so (thus the name "Summer Ducks"), but they'll be back soon enough. I look forward to seeing them once again flying through flooded woods, the drakes giving their whistles, while the hens their distinctive "Oooo-eeek" calls... one of my favorite sounds at dawn and dusk...

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