A winter expedition
of the Bishops Mills
Natural History Centre
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Robins' Winter Feast on Kemptville Creek
Field notes of Frederick W. & Aleta Karstad Schueler
visit. 2003/010/b Canada: Ontario: Grenville County: Oxford-on-Rideau: Kemptville Creek/1.0 km NNE Hutchins Corners. MAP:31B/13, UTM 18TVE 453.5 754.5. 44.93237N 75.69215W
25 January 2003 TIME: 1200-1335. AIR TEMP: -4C, overcast, windy
COLLECTED BY: Frederick W., Aleta Karstad, & Jennifer H. Schueler, Keith McIlwaine, Ali MacKeen Field#: 2003/010/b
HABITAT: spring seepage into marshy creek, Soft Maple/Ash woods
WAYPT/036. Snow about 25cm deep - a peculiar greasy texture of granular snow with no layering, like a mass of tiny plastic beads, even though it fell over the course of many days.
At about 13:35 I gave up waiting for the Robins to come down again, as the wind and snow were increasing and Fred and Jennifer who had gone ahead were waiting at the truck with the buckets of live fish.
At 13:05, while I was warming my camera and batteries separately inside my coat, I actually saw a Robin swallow a small Sunfish which it dipped out of the narrow gap of open water and battered briefly on the ice edge. At the same time four other Robins were drinking water together at the upstream end of the 5m gap. This is a long s-shaped opening by the west bank of Kemptville Creek, a few kilometres northeast of Bishops Mills.
We were taken there today by Keith McIlwaine, who had discovered the Robins there 6 days ago while he and Ali MacKeen skied down the creek from their home. On that Sunday outing they noticed Robins flying across the creek, and upon approaching an opening in the ice where they knew the creek flows shallowly across a broad slab of limestone, many Robins flew up from the ice where it appeared they had been picking at exposed mossy-textured water plants and eating small dead fish which littered the snowy ice around the opening. The smaller of their two dogs broke through the ice at the edge, exposing a roiling mass of young Mudpout (Brown Bullhead)!
Today's development, six days later, appeared to be many dead Sunfish (Lepomis sp.) floating on the surface of the open water, and glimmering on the bottom. The large overwintering tadpoles which Keith had described were still there, moving sluggishly into view and then back beneath the ice edge, and very cute black, whiskery baby Bullheads of 2 - 3cm in length also moved about, some wriggling up into the slush on ice that broke beneath our weight.
One 70mm Leopard Frog was dipped out, eyes depressed and skin a blackish kelly green. Whether they actually feel pain at being disturbed in their helpless torpid state, hibernating frogs always look extremely uncomfortable. We replaced it and caught a smaller, more active individual, and also a single Mink Frog!
When Jennifer moved to the downstream end of the opening, she found much more fish activity, and ice broken away revealed dense, roiling crowds of young Sunfish and Rock Bass, including a few two-year-olds, some larger Bullheads, and many small 'minnows' which we have not identified yet. These may have come upstream, following the trail of better-oxygenated water flowing from the opening.
Keith also showed us the open pool of a spring, just a few snowy metres across the creek bank from the upstream end of the long gap in the ice. Fred measured the water temperature at that end of the gap (where I subsequently watched the group of Robins at their drinking party) and found it 5C, but the temperature of the water in the spring pool was 8C!
Ali skied down to us with their dogs, and the Border Collie mix hunted fish like a spring Bear, wading in, snatching live Sunfish with a wet muzzle, dropping a flipping fish on the snowy bank, and then munching it up. The only way to discourage this activity was to leave, which Ali did, and Keith went back to his truck while Fred and Jennifer gathered our buckets and nets onto the sled and left me to wait for the Robins to return, in hopes of a photograph.
I stood very still and I guess the birds thought that we were all gone up the creek. After 5 or 10 minutes, during which I warmed my camera and batteries, the ice-storm-blasted Ash grove was alive with a flock of Robins, glowing and flitting like bright wind-blown leaves through the grey-twigged woods, voicing curt, husky peeps, and also their two-note call. Gradually more and more came to perch among high branches above the creek bank, so eventually I could count more than thirty. Some flipped tails, flirted, fluffed, and seemed to be thinking about descending to the feast - and a few minutes later there were three, evenly spaced along the the open water, pecking at the edge, stretching their necks, and peering into the water. That is when I made the observations I have described above, of fishing and drinking.
After about five minutes at the opening for 6 or 7 birds, they flew up, one by one, and the whole flock then went through the grey woods in a downstream direction and although I then took the oportunity to load warmed batteries into a thawed camera, they did not return and I gave up after half an hour of waiting in the cold wind and increasing snow.
A tuft of Robin back or neck skin & feathers on the ice shows that some predator is harvesting them...
slow seepage fr spring on W side of united creek channel, over ridged bedrock bottom. 5x0.5m open area, 5-10cm deep, muddy/sandy bottom blw bedrock, water 5.5C. Surrounding snow all tracked up by, and stained with greenish stuff pulled up by, Robins. Little dead Lepomis and a few Rana tadpoles scattered around on the snow. (Infow?) water dark brown.
There's a 20cm-diameter hole in the snow up on the bank which seems to be the actual spring - and in that the water temperature is an almost unbeliveable 8C or 8.5C. This isn't very deep, just 5cm or so.
A few adult Rana seen alive by Keith as we just arrived...
Most of the dead fish were Lepomis gibbosus, and Amblopites, Umbra, Phoxinus, and Culaea were under-represented among the dead (in fact I'm not sure I saw any of these dead when we arrived, though our ice turning, muddling, and netting threw numbers of them up onto the ice (except I didn't see any Culaea for sure). JHS turned up some slabs of ice with barely any water under them where the fish were nearly continuous under the ice, and the colours of the lying-flat Lepomis as brilliant as an oriental carpet...
There were no great numbers of dead Lepomis here on 19 January at Keith & Ali's previous visit - what they saw then was mostly living Amieurus and Rana.
We surmise that the fish are attracted by the oxygen in the open water and the inflow water, and that since 19 Jan the levels have fallen to the lethal point for many Lepomis, though not for the other fish species. I suppose I ought to go back and whack away a big area downstream and see if frogs are aggregated around the hole, since the water depth isn't sufficient for many of them where we were working. Water levels have been low and uniform this winter, so ice cover is complete and uniform, just as it was with higher water levels in 2000-2001 when the water was 'cat-farts' anoxic below the dam in Oxford Mills.
Determined by: F.W.Schueler; Site accuracy: 50m waypoint Coordinates from: GPS:L/L-WGS84,UTM-NAD27Canada; EOBase entry: FWSOBS FWS/2003Jan26/10/012; source: FWS/biography/as entered/EOBM; record last modified: FWS/2003Jan26/1452:39.