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Flooding Affects Wildlife

What a difference a year can make! The “new normal” for our climate continues to bring wild swings to extremes. We have seen conditions way too dry, way too cold and now way too wet in the past 12 months. Way too hot is all that’s left to round things out for what would then be an “average” year, and there’s plenty of summer left for that to happen.

The flood of 2014 has not been as high as several of the other floods we’ve seen since the early 1990s. At least, not so far. There are chances for strong storms again this evening as I write this early Monday morning, though. With the ground saturated, anything that falls will soon be in our streams, bringing them back up again. Most plants don’t grow well with their roots in completely saturated soil. Both of my garden plots would be in sad shape by now if the plants weren’t growing on raised beds. Most woody plants can survive having their roots under water for a few days, as long as their branches and leaves remain above the flood. Species that normally grow on flood plains like willows, cottonwoods, sycamores and silver maples, can live for months under flooded conditions. Trees like walnuts, green ash, hackberry, elms and even bur oaks can survive a few weeks of flooding, but true upland species like white oaks, red oaks, hard maples and hickories are likely to die if their roots are in saturated soil for very long. All trees are more susceptible to wind throw (being tipped out of the ground, roots and all) when they’re in saturated soil.

Wildlife is affected by floods, as well, but most adult animals and birds are mobile enough to get out of the way as waters rise. Ground nesting birds like pheasants, turkeys, meadow larks and waterfowl can lose nests to rising waters, though. Even a few hours in the water will kill unhatched eggs. There’s no doubt that some nests were lost in the past few weeks; especially where hens were forced to make second nest attempts after losing their first nests to predators, mowers or earlier storms. Many nests should have hatched before conditions got too wet, though. Young pheasants, turkeys and waterfowl are able to move about and feed themselves within a few hours of hatching. Waterfowl, once hatched, can take quite a bit of water, and upland birds will follow their mothers to higher ground. Mobile young birds may not drown, but they still depend on their mothers to keep them dry and warm. Their little bodies can’t regulate temperature very well for the first couple of weeks until their feathers grow in. They remain very vulnerable to chilling and death if they stay wet too long. Ground nesting songbird nestlings are pretty much out of luck if caught in rising water.

Most larger mammal babies, like deer, foxes and raccoons, would be mature enough by now to move away from rising water, but the less mobile young of some smaller mammals have no doubt drowned. Of greater concern is the fact that suitable habitat can be very limited when birds and animals are forced from their homes by rising water. Most drier upland areas were converted to cropland long ago, and today’s clean-farmed row crops offer little in the way of food or cover. Lack of cover leaves wildlife much more vulnerable to predation, and high water can also disrupt food availability. The last areas of permanent vegetation that might offer some food and cover in much of our area are road ditches and grassed waterways, the very areas most likely to flood during heavy runoff.

How bad will this year’s flooding affect wildlife? Only time will tell. There’s still a good portion of the growing and nesting season ahead. A return to more stable conditions will allow many plants, birds and animals to come through OK. One thing is sure, though. Wildlife in marginal habitat doesn’t have many options. When conditions are anything but ideal, they’re not going to do very well. Diverse upland and lowland habitat is necessary for wildlife to thrive in Iowa’s often dramatic weather extremes.
