Conversion of Lake to Wetland Habitat Predicted to Provide Habitat for Rails
Dr. Jim Kellam, Associate Professor of Biology, Saint Vincent College
May 5, 2022
May and June are peak months of activity for most birds, which means as an ornithologist, I am at my busiest, too. I am working on several research projects right now, including one that is centered on Saint Vincent Lake. The lake is just down the hill from the Saint Vincent College campus near Latrobe, Pennsylvania. It is a 4-foot deep, 12-acre impoundment built in 1921 for recreation. Its banks are eroding and water quality is failing. The Archabbey at Saint Vincent will drain it and convert it to wetlands over the next few years with help from various state and local organizations with such expertise. I’m not aware of the exact timeline, but I know a good research project when I see one. The conversion of the lake to wetlands will cause a drastic change in habitat, and with that, a change in the birds that live there. We will definitely lose the open water that migratory ducks and mergansers use for a stopover site in late winter as they migrate north to their Canadian breeding grounds. We will also stop seeing a Bald Eagle or Osprey perched in a tree overlooking the lake, hoping for an easy fish to catch. But what might we gain?
I suspect a lot, but you may not know the names of the birds that are going to benefit from the new wetland. For example, the nearby abandoned mine drainage ponds have areas of cattails that are inhabited by Sora and Virginia Rail. The new wetlands we build will hopefully provide more and better habitat. Rails (including the Sora) are chicken-sized marsh birds that dwell on the ground and are rarely ever seen. They are migratory and arrive in wetland habitats throughout Pennsylvania in late April. Male and female both incubate and care for the eight or more young from each weed-woven nest. Sora densities average about 1.3 pairs per hectare in good habitat. If our new wetland is successful, we could host up six pairs of the birds!
For the next few years, my students and I will be conducting point-count surveys around the lake to document the presence and number of bird species found there. Point-counts are 5-minute “snapshots” of what birds we detect by sight or sound within a 50-meter radius of five preset survey locations. We’ll do them at regular intervals at the same time each week, and we’ll do them all summer to make sure we don’t miss any species living in the area. Students are in the midst of exams this week, so today I conducted the point counts alone. Across the five points, I documented 32 species. We won’t ignore American Robins and Northern Cardinals in these surveys, but these species are so common they will likely be in the area both before and after the lake is converted to a wetland. In contrast, the point counts may show an increase in Prothonotary Warbler, Common Yellowthroat, Willow Flycatcher, Marsh Wren, Wood Duck, Sora, and Virginia Rail.
The rails are secretive and may be missed by the point-count method. Therefore, we will do a sound playback survey once every two weeks at the five point-count locations. This involves playing prerecorded bird calls using a wireless speaker and listening for any live birds responding to the recording. This technique is potentially disruptive to the birds, so it should not be repeated over and over; we will play just 30-seconds of sound each time. The American Birding Association discourages anyone NOT doing a research study from employing this technique.
The Sora and Virginia Rail are not especially colorful birds, and given how secretive they can be, you might wonder why I care about them. Are they as exciting as a Bald Eagle? I say yes! The mature Bald Eagle is striking in its contrast of white and brown feathers. They are large and perch out in the open, making them fairly easy to watch. It’s fun to think of them watching over us as protectors, and certainly we feel patriotic seeing our national symbol. If this blog post was about the eagle, I’d list many more of its positive attributes. But this post is about marsh land birds. The rails are striking not in their visibility but in their invisibility. To see or hear one is to find the unknown in the midst of the familiar. They are the pearl inside a clam, the meteor streaking through a night sky, the biggest tree trunk you find in the forest! Your jaw drops when you know you have found a rail, in literally the same way your jaw drops when you see an eagle or any of those other rare events I mentioned. For an example, take a look at this video I produced for my ‘Biology of Birds’ students: https://youtu.be/dQs89HR7ljA . In the video, I am talking to the camera and when I hear a Virginia Rail give a call, my eyes light up, I smile, and I can’t wait to point it out to my student viewers. I had this reaction even though I was totally expecting to hear and see a rail that day. That was the point of making the video, and yet, I couldn’t contain my delight. To be able to host potentially six more pairs of these birds at Saint Vincent Lake means I’ll have that many more opportunities for such joy. Not only that, but when rarer species become a little more common, they contribute to the health of the food web and the ability of the ecological community to show resilience in the face of both natural and human disturbance.
I hope you see now why eagles and rails are equivalent to me. They also live and depend on wetland habitat for their food and nesting sites, and wetlands have been drained and degraded by people for generations. This is why the conversion of a lake to a wetland is exciting. We are turning back the clock, little by little, to a time when nature was more diverse and better able to take care of itself.