Impact of Flooding at the Oak Lake/Plum Lake IBA

Thank you to David Hatch for this detailed account of the effects of flooding in the Oak Lake/Plum Lake IBA area.

July 8, 2014

Immediate impacts on local nesting birds of the massive flooding in the Oak Lake area of southwestern Manitoba

Over a four-day period between Thursday, June 26 and Sunday, June 29, the area received 200-215 mm of rain, coupled with winds in the 70 kilometre range on the final day. Prior to this deluge, the area was already saturated with far too much rain.

Oak Lake [the actual lake] and its massive network of wetlands, meadows, pastures croplands and aspen woods, plus the Oak Lake recreational area are located southwest of the town of the same name and are south of Hwy. #1 and north of Hwy. #2. The wetland complex is also primarily west of Road 140 W and east of Road 150 W.

The impact of this latest flooding is devastating to local farmers and extremely disheartening, so it is almost sacrilege for me, raised in the local area and still where my heart resides, to talk about the impacts on birds.

The colonies of Franklin’s Gulls, Black-crowned Night Herons and Eared Grebes are drowned out, becoming parts of broad expanses of open water. So also are two of the three Cattle Egret colonies. One small colony of 200-300 birds still remains and here is some good news. It is a site of frantic activity with many birds carrying stocks and leaves of aquatic vegetation to rebuild or raise their nests as the water continues to rise. In mid-June, this particular colony also had six or more Great Egrets and at least one Snowy Egret hanging around it and possible nesting. Both species are still present and they are also carrying nesting material.

The biggest surprise was that now Black -crowned Night Herons and as many as 17 White-faced Ibis have arrived in this maze of cattail beds and are carrying nesting material. Possibly, they are birds flooded out from other wetlands and, finding this colony still intact, have decided to try a new area. To reach this colony one has to know the terrain very well and trudge and wade for nearly two hours to get close enough to see with a telescope what is occurring. I remained still a long distance from these colonial nesters so as not to disturb them.

Although White-faced Ibis have been in the Oak Lake marshes in the nesting season during 2012 and 2013, I have not had any evidence that they were nesting, but from a distance it sure appeared that they were this week. This year was the first year that I have had any evidence that Cattle Egrets or any other egrets were nesting in the Oak Lake area, even though they arrive in the area in late August annually now and remain well into October. In the fall of 2012 and 2013, some of the roosts were attracting hundreds of birds with it possible to see a dozen flocks of 10-25 birds arrive before dusk to spend the night in the cattails.

I only spent July 2 and 3 in the Oak Lake area, but there was not a Franklin’s Gull around. Where could thousands of pairs go so quickly? Are they searching for a new possible colony site far from here or has their nesting season ended for 2014? Many local residents enjoy birds and have oriole feeders, which every summer are daily used by both Orchard Orioles and Baltimore Orioles. Every person with an oriole feeder told me they had not seen an oriole since the heavy rains and furious winds of June 29. One couple had been enjoying watching a Baltimore Oriole on its nest on a low branch of an American Elm only three meters from the oriole feeder, but the bird disappeared in the winds. Last year it had nested within a meter or two of the same location and given the family great pleasure. Where would all the orioles go so suddenly after the rainstorm? I did not record either species during this visit.

The number of pairs of Gadwall, Blue-winged Teal, Lesser Scaup and Redheads observed was astonishing. Will these four species of late nesters still attempt to raise a brood? Nesting habitat is at a premium as many meadows and pasture fields have stretches of flood waters that extend for 2000-3000 acres across them. The marshes have become open water devoid of the emergent vegetation essential to anchor and protect floating nests.

Even Hwy #256, which connects Oak Lake Provincial Park, resort and golf course with the TransCanada Hwy has a third of a meter of water over the pavement, but is still open to traffic.

I spent much time off the west side of the lake utilizing Road 150 W, where it was passable and a few connecting roads. Despite the challenge, I recorded four singing Chestnut-collared Longspurs and 13 Sprague’s Pipits. Both species were doing a great deal of singing. With little patches of dry ground and the cool temperatures, hopefully there will be much re-nesting for these now-scarce, prairie residents.

Large numbers of three other grassland-nesting species, were also highly vocal and may also make another nesting attempt. They were Willet [heard in eight sited] and the much more common locally Upland Sandpiper and Marbled Godwit. Even if these species had young before the major four-day storm, it would have been difficult for their offspring to survive the overland flooding. All three species were making so much noise that it sounded like they had just returned from the south in spring and were staking out territories. Upland Sandpiper, which can have a prolonged nesting season, are often seen in the Oak Lake area with young as late as in the first week of August, but normally the Willets and Marbled Godwits are drifting south out of the Oak Lake area by then.

Finally, one last piece of really good news. Both pairs of Trumpeter Swans, which had broods on my mid-June visit, were located and still have their broods. They nested in quiet, isolated marshes, but now that everything is so flooded, they are so conspicuous from the air, that they look like white sailing ships on a lake.

Please respect private land and indeed all land and give these species a chance to salvage their nesting season. In my travels around the world, I have seen so many researchers and photographers in particular do much damage to breeding birds, that I am very guarded in ever reporting breeding bird activity, but felt the damage from this flooding and the stories associated with it should be passed along. The less disturbance nesting birds have by humans, the better it is for the birds.

Good birding,

David Hatch