A High Point to Low Water Levels


Hearing that lakes and streams are at record low levels this summer has become a weekly ritual. Halton Region and the County of Wellington have continually encouraged residents to conserve water through voluntary measures. The Town of Oakville asked homeowners to water roadside trees to avoid potential death during drought periods. In all of this news there seems to be a lack of both water and positive ecological effects. However, any birder who has been to Mountsberg Conservation Area in the last month may be whistling a different tune.

It is true that water levels in the Mountsberg reservoir have dropped drastically over the last four months. Although it’s not unusual to see old tree stumps this time of year, the area exposed seems to be much larger than the historical norm. The lack of rain has forced Conservation Halton reservoir operators to drop levels approximately half a metre lower than would be typical at this time of year, and levels are currently at the lowest summer levels that they have been since the reservoir was installed in 1967.  Originally built to control water levels during periods of both high and low precipitation, the recent draw-down has created a new habitat niche in the resulting mudflats. The first to take full advantage of, and benefit from this area are migrating shorebirds.

With breeding and summer habitat far north on Baffin Island, the Baird’s Sandpiper seems to have taken a pit-stop at Mountsberg on its way back to Argentina. From here it will continue on its flight path to South America where it will spend the winter before returning up north. This bird has been joined by dozens of Lesser Yellowlegs, Least Sandpipers, Killdeer, and Semipalmated Sandpipers, to name a few. Birders have watched an interesting show between a Peregrine Falcon and a Bald Eagle, both vying for the role of top predator in this ecosystem. The Red-Necked Phalarope and American Golden-Plover, both must-sees on a birder’s list, have been a focal point in the last few weeks, as birders shift schedules to see these species before they move on. Therecord count for American Golden-Plover in the Hamilton Area is 350, seen in 1978, while the Red-Necked Phalarope has a record count of only 13, seen at the Dundas Marsh in 1974[i].

This new and likely short, burst in bird diversity is a gentle reminder that ecological systems are always in flux. Changes to one part of an ecosystem will have both positive and negative effects for the species which depend on it. Stop by the Mountsberg reservoir to see the birds in action, but be sure to bring a pair of binoculars as many of these visitors are quite small in stature.

Bird’s of Note

Common Name Maximum Number Seen Month Seen
Lesser Yellowlegs 25 July, August, September
Greater Yellowlegs 3 July, August
Least Sandpiper 35 July, August, September
Baird’s Sandpiper 3 July, September
Pectoral Sandpiper 31 July, September
White-rumped Sandpiper 10 August
Stilt Sandpiper 1 July
Spotted Sandpiper 5 July, September
Semipalmated Sandpiper 40 August
Solitary Sandpiper 7 July
Killdeer 50 August
Great Egret 7 August, September
Short-billed Dowitcher 1 August
Red-necked Phalarope 1 July
Peregrine Falcon 1 September
Bald Eagle 1 September
American Golden-Plover 1 September
Semipalmated Plover 1 August
Green-winged Teal Many September
Philadelphia Vireo 1 September
Great Crested Flycatcher 1 September
Horned Grebe 4 September
American Coot 40 September
Ring-necked Duck 45 September
Ruddy Duck 13 September
Redhead 1 September
Lesser Scaup 1 September
Nelson’s Sparrow 1 October
Long-tailed Duck 1 October

[i] Curry, R. 2006. Birds of Hamilton and Surrounding Areas. Hamilton Naturalists’ Club. Hamilton, Ontario.

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