Lake Ontario diving ducks
Bruce and Laurie Mackenzie
Hello,
Yesterday Lake Ontario was totally calm when looking out from Fifty Point for the Peach Tree Christmas Bird Count.
Diving ducks were seen in all directions as far as you could see with a spotting scope.
They were in the tens of thousands.
Diving ducks were easily seen what was most likely 2 miles or more from shore. When looking towards Burlington it looked liked ducks were scattered over all of the waters between Fifty Point and Burlington.
At the far reaches we could not identify the ducks as to species but where we could see and identify them they were primarily:
Long Tailed Ducks and the three species of Scoters. Where there scoters in the far reaches of our site and in deeper waters?
I read on web sites that Long-tail Ducks can dive to 200 ft but scoters are described as diving less than 40 ft.
Assuming that if a diving duck is on the water it is on water that has a depth that it finds suitable for diving to the bottom for feeding. When looking at the depth contour map on the link below we can see that Lake Ontario is relatively shallow even a mile or more out from shore in the west end of Lake Ontario.
This large expanse of shallow water being suitable for diving ducks is most likely one of the reasons that so many ducks are seen in this part of Lake Ontario and the western end of the lake is identified as an Important Bird Area.
To help reference my distances as to how far ducks are off shore I use my experience with the distance from shore that the Winona rifle range buoys are normally located. Please note the buoys have been taken out for the winter so my reference is based on memory. The placement outline for the buoys is seen in the above link if you expand the view.
Looking almost due north from Fifty Point we can see the depth at about 3.75 miles is just less than 100ft.
At 2.5 miles it is less than 65 ft. If you look west from the Fifty Point land spit to downtown Burlington you are looking at a distance of 11.5 miles over water that almost gets to 100 ft deep closer to the Burlington shoreline.
Thus all of these waters are suitable for at least Long-tailed Ducks feeding.
So if what I read about scoters in terms of diving depth is correct then should they all be within a mile or so of shore or in less than 40 feet of water?
Or in Lake Ontario, could scoters be diving to greater depths of 40 feet. One of the things I will have to look closely at is what ducks are actually diving in the deeper waters. Of course ducks could be loafing in deeper waters and moving into shallow waters for feeding.
Assuming that Zebra and Quagga Mussels are the main food item of these diving ducks one could ask to what depth do these introduced mussels live in western Lake Ontario. In this link we read that Quagga mussels can be found up to a depth of 540 ft. in Lake Michigan. Quagga mussels are close relatives of Zebra Mussels.
https://cisr.ucr.edu/invasive-species/quagga-zebra-mussels
In the following link we see that Zebra mussels are found generally in (164 ft) 50 m or less of water in Lake Ontario. Thus it is likely that both zebra mussels and quagga mussels could be found in the waters off of Fifty Point within scope sighting distance for ducks. The 164 ft contour is at least 5 miles north of Fifty Point.
https://www.sciencedirect.com/science/article/pii/S0380133021001726
Would be pleased to hear from others as to their experience with how far Scoters are seen diving and feeding from shore in Lake Ontario.
Thanks
Bruce Mackenzie