Tuesday, July 16, 2013

Flood Aftermath - Three Weeks Later

Flood Aftermath - Three Weeks Later

The flood on June 20, 2013 devastated wildlife families in the flood plain along the Elbow River. 

Those birds that nested in the shallow grass by the sides of the river or on land adjacent to the river (Mallard, American Widgeon, Gadwall, Spotted Sandpiper), in trees within about five meters of the river (Yellow Warbler), or in the banks of the river (Bank and Northern Rough-winged Swallows, Kingfishers) were severely affected.

Bank and Northern Rough-winged Swallows lost all their nests. Bank Swallows are usually double brooded, and after making a new nest, might have a new clutch this year. However, since the third day after the flood I have not seen a Bank Swallow. The hundred or so Bank Swallows that were nesting have relocated somewhere else. 

Northern Rough-winged Swallows are reported to be only single brooded but I have seen several new pairs nesting in a different location along the Elbow River.

The Kingfisher mating pair lost their nest. These birds are usually single brooded, but are reported to fashion a new nest and replace the clutch if the first is lost. However, similar to the Bank Swallows, I have not seen or heard a Kingfisher since the third day after the flood, which implies these birds have relocated.

Yellow Warblers nest 1 to 3 meters up in Willows and many nests were lost. Based on call-identification, less than a third of the nests survived. However, some did. I saw a Yellow Warbler feeding a Cowbird (parasitized nest).

Spotted Sandpipers nest on the ground by the river and these birds lost all their nests. This is the most common bird on the river. I usually see or hear at least ten each time I do my customary hike. Lately I have seen or heard zero to two birds. 

Birds who nested higher up or who nested inland were less affected. Larger birds with young that hatched in May and early June (Canadian Geese, Common Merganser) were affected less than the smaller birds who hatched later in June. 

These three young Mallards were alone without a mother, which implies that the mother was lost, perhaps in the flood, or alternatively to other causes. These birds are larger and likely hatched in early June and their size is a survival factor.
Geese arrive and nest early and these goslings were likely hatched in May and able to walk inland or otherwise survive when the flood waters started to rise.

These six larger Mallard young likely hatched in late May or early June and were in the runoff reservoir, which suffered only a modest rise in water. Their size and the nesting location allowed survival. On the same day as this photo, I saw a 8 chicks with a mother on the reservoir. These chicks were still in the egg at the time of the flood, and had this mother nested on the river, these chicks would not be alive today. Similarly, I saw a Ring-necked Duck family with chicks about two weeks old. Ring-necked Ducks choose marshy ponds rather than rivers to nest, and were therefore at much less risk.  
These five larger Gadwall young hatched in late May or early June and were in the runoff reservoir, which suffered only a modest rise in water. Their size and the nesting location allowed survival.

This photo shows four of six young Common Mergansers . Mergansers, like Geese, are larger and nest earlier, and these youngsters were older and strong enough to survive the turbulent flood waters. However, I also saw one Merganser family that was not so lucky. Over the last few days I saw a solitary female Common Merganser in the same location that I saw a female with a solitary chick on June 17, three days before the flood. This adult was sleeping on the shore across the river two days ago but the next day I heard the Common Merganser alarm call from the adult. This call usually implies the presence of chicks, but I only saw the solitary female.  I suspect this female lost her chick in the flood. 

There was an American Widgeon pair nesting on land close to the Elbow River before the flood and these ducks have disappeared. I presume their nest was lost. 

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