Reports
Nov 19, 2013 - Lake Simcoe Migrants Trip Report
2013-11-09 Lake Simcoe Migrants Field Trip
Chris Evans
It was a dark and stormy night … wait, that’s a different report. It was great weather for ducks! It was generally overcast, 0 to 1C, winds S 9km/h shifting to SSE 15km/h gusting to 28km/h with the occasional drizzle or flurry until about 08:30.
We met at LLPL and left for Tyndale Park shortly after 8:00 am with 3 vehicles and 7 people, including Ken and Susan MacDonald representing the Midland-Penetanguishene Field Naturalists. On our arrival at Tyndale Park we were greeted by 12 more enthusiastic people, (11 BFNC members & a guest). Two more BFNC members joined us at Tollendal Woods Park and another at Minet’s Point for a total of 22 people including our 3 welcomed guests. Our numbers began to dwindle as we reached the Spirit Catcher due to the raw winds gusting from the SSE from which we had been relatively sheltered on our earlier stops along the south shore.
Our itinerary was as follows: Tyndale Park; Tollendal Woods Park; Minet's Point; Southshore Community Centre and the Spirit Catcher.
I had intended to stop at the Tiffin St. Boat Launch and Centennial Beach, but there wasn’t significant bird activity in either area on this occasion which couldn’t be observed from the SSCC. I decided to call the trip at about 10:30AM as people were getting cold and the SSE winds would exacerbate that situation along the north shore, plus, there didn’t appear to be any likelihood of encountering new species nor better views by continuing.
The large flocks of gulls, loons and cormorants of the preceding weeks were not in evidence as the large shoals of Emerald Shiners had subsided. I conducted a brief internet search on these widespread, abundant, 10cm long, North American freshwater minnows. It is reported these fish move to deeper water to overwinter. They are very adaptable to, and tolerant of, large water temperature changes. This adaptability is reportedly attributable to their short life span of 3 years. Based on these reported facts, I speculate that the large shoals we see at the west end of Kempenfelt Bay in the fall are migrating from the shallower pelagic waters of Lake Simcoe and its tributary rivers and creeks, coming to the deeper waters of Kempenfelt Bay to winter. I further speculate that they are at or near the surface when they first arrive, as this is where they normally feed in summer and fall. Thus, they initially provide abundant and accessible forage for the surface and shallow feeding gulls, as well as for the cormorants, loons, grebes and diving ducks. This may explain why the deeper diving cormorants, loons and grebes linger longer as they continue to enjoy this bounty as the shiners seek out the deeper water until the Bay freezes over.
I offered the information to the group that the Common Loon usually dives between 4 to 10m but has been reported diving as far down as down to 60m to 80m. John Warnica offered information about a very interesting ocular adaptation of the Common Loon to the extreme pressures they experience during deep dives. Apparently, as they approach these depths their eyes increasingly flatten, the cornea being pushed toward the retina along the visual axis of the eye. These changes in geometry would normally make them increasingly farsighted the deeper they dove, making it impossible for them to focus on the prey they are pursuing. So they have evolved a special adaptation of the lens in their eye. As the pressure increases, the lens bulges through the pupil, changing the shape of the outer surface of the lens and maintaining its distance from the retina, thus, compensating for the shortening focal distance in the rest of the eye created by the flattening and pushing of the cornea towards the retina.
He suggested cormorants and other deep divers had similar adaptations. An internet search also found that cormorants had a range of accommodation of 50 diopters, whereas, in humans, this range is limited to a maximum of 15 diopters.
Another excellent question was “What is the origin of “Bonaparte’s” in the common name for Larus philadelphia. Ken MacDonald did some Googling and passed on an interesting and amusing dissertation on this very subject at this link … http://www.birdwatchersgeneralstore.com/BonaparteGulls.htm
Now, back to the report!
Sightings: (all numbers are very approximate, “in-the-order-of”)
25 Common Merganser,
100 Common Loon, were generally strung out in the middle of the Bay
50 Mallard,
500 Common Goldeneye,
30 Hooded Merganser,
10 Red-necked Grebe,
10 Horned Grebe,
2 Red-breasted Merganser,
50 Bufflehead,
40 Scaup (likely Lesser, perhaps a few Greater),
15 American Black Duck,
200 Ring-billed Gull,
15 Great Black-backed Gull,
30 Herring Gull,
25 Bonaparte's Gull,
2 Little Gull, seen in the middle of the Bay off Tollendal Woods Park
1 Golden-crowned Kinglet,
25 Double-crested Cormorants,
5 Long-tailed Ducks,
1 Cooper's Hawk,
10 American Crow,
5 European Starling,
20 Canada Goose,
1 White-breasted Nuthatch,
50 Rock Pigeon
The Little Gulls were along with a few Bonaparte’s which were sparsely spread from Tyndale to the Spirit Catcher. The other gulls and cormorants were mainly concentrated from Minet’s Point to the Spirit Catcher. Long-tailed Ducks at Minet’s Point. ROPIs downtown. Canada Geese @ Centennial Beach. Goldeneye and Scaup from Tyndale to Tollendal. Black & Mallard Tyndale to Minet’s. Cooper’s Hawk caught a European Starling @ Minet’s Point Road and Lakeshore Drive while being harassed by some Crows.