Prothonotary Warbler

Prothonotary Warbler

Thursday, 13 March 2014

Winter can be tough on birds, too!

Many birds fly south for the winter, not so much because of the cold, but because they cannot find food. Insect eaters, for example, just don't have a food source. However if birds think they can find enough food to survive an average winter, they might stay. But if it isn't an average winter, like the current one, it can be challenging indeed, even deadly.

Here in southwestern Ontario many ducks spent the winter on the St. Clair River, where patches of open water persisted. However Canvasbacks and Redheads, normally vegetation eaters, were running out of vegetation. Some photographers noted them feeding on live fish, which is highly unusual. It is almost unheard of, according to some waterfowl biologists. But checking the literature, such as F. H. Kortright's classic book Ducks, Geese and Swans of North America, apparently the winter diet of Canvasback was determined to be up to 2% fish in more southerly wintering areas. Given the paucity of vegetation in the limited areas of the St. Clair River, it is quite likely that the per cent of fish in their diet was much higher!

Although I didn't notice this behaviour in 2014, I had documented it in 2011, when I photographed both Canvasback and Redhead feeding on and fighting for live fish.

Male Canvasback eating a live fish, being harassed by two male Redheads


The lower photo shows a male and a female Canvasback moving in on a male Canvasback feeding on a fish. Sometimes the harassment results in the bird giving up its meal.

When fish or vegetation isn't available, ducks will feed on whatever they can to survive, including molluscs such as Zebra Mussels. Ducks such as Greater and Lesser Scaup feed on these types of molluscs regularly at other times of the year already, but Canvasback and Redhead will not choose molluscs if vegetation is available. The two images below show first a Canvasback swallowing a cluster of Zebra Mussels, followed by a Redhead doing the same. These two photos were taken in the main channel at Erieau in mid March of 2008, which was another harsh winter with lots of ice cover.



But even then, some ducks don't make it through the winter. The photo below shows a dead Redhead floating in the water close by a resting pair of Canvasback. There have been quite a few dead waterfowl noted floating on the water this winter, or washed up on shore of bodies of water where they attempted to over winter.


This dead Canvasback below was floating along on the St. Clair River when a Herring Gull swooped down to check it out. After plucking out a few feathers, the gull moved on....apparently it wasn't hungry enough to warrant the effort to get to the meat of the issue! So the dead duck continued floating downstream, minus a few feathers. I'm sure it didn't feel extra cold.

While out today, I noted a vulture feeding on a carcass of something out in a field. Knowing that a Black Vulture had been seen in the general area a week or so ago, I wanted to get a closer look. Interestingly a Black Vulture was present, feeding on a road-killed opossum, within a couple of kilometres of this same location exactly 5 years ago. Turns out this one was a Turkey Vulture, however. TVs are just arriving back into southern Ontario these last few days, although surprisingly there have been a handful present most of the winter. This vulture too, was feeding on an opossum, which are becoming increasingly common in southern Ontario.


Seed-eating birds have generally had a better time of it this winter. Of course keeping feeders stocked with seed always helps! This male Eastern Towhee arrived at the Rondeau Visitor Centre feeders back in December, and has been feeding several times daily ever since.


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