What Could These Ducks Be Eating?

 

     No matter where you may find yourself birding in Connecticut, it is always important to be aware of you’re surroundings. Keeping focused in the field can often lead to discoveries that would otherwise go unnoticed.

     Last week at Riverside Park, I caught sight of a small mussel washed up along the banks of the Connecticut River. As I admired the beauty of the mussel in my hand, I thought back to a sighting I had of a female American Scoter at this very location. It spent the entire month of January feeding and resting just off the boat launch. I remember asking myself, why does this bird favor this part of the river? What could it possibly be eating down there?

     The mussel I found and photographed here is called an alewife floater. It is one of twelve species of freshwater mussels native to Connecticut. The alewife floater is still considered an abundant species in the Connecticut River, where it lives in mud, sand and gravel bottoms. Was this mussel sustaining the scoter in Hartford?

                      www.ct.gov/dep/cwp/view.asp?a=2723&q=325894&depNav_GID=1655

     Another question which came to mind while I was reading about freshwater mussels, involved the occurrence of overwintering Common Goldeneyes. Why are Common Goldeneyes found in such large numbers in Enfield, and absent elsewhere in Hartford County? With a coastal diet of primarily mollusks and crustaceans, is there a similar habitat or condition in Enfield that supports a healthy population of mussels, and in turn, a healthy population of Common Goldeneye?

South River Street Boat Launch
Enfield

                          

     To help answer these questions, I turned to Doug Smith of the University of Massachusetts Amherst.  http://www.bio.umass.edu/biology/conn.river/fwmussel.html

 He wrote,

 Paul,
 Well here's what might be happening. The Enfield rapids are shallow and
the substrate is rocky with sand and silt, especially since the old pier
wore away. Many years ago (over 30) I studied that section of the
Connecticut because it was a historical location for many mollusk
species, many since extirpated. What I did find was that section of the
river was the only one that still supported a decent population of the
Virginia river snail, Pleurocera (=Goniobasis, =Elimia) virginica, a
relatively large (10-20 mmm) snail living on the hard substrate (Smith,
DG, 1980. The Nautilus 94(2):50;http://www.biodiversitylibrary.org/item/34223#page/66/mode/1up). Two
mussels, Elliptio complanata and Anodonta implicata, were also fairly
common. Since about 1991, an invasive species of clam has become
established, the Asian clam, Corbicula fluminea, and is quite abundant
in the lower part of the river. It is possible that it has migrated
upstream to provide an additional source of food. Over the last twenty
years, due to clean up efforts, the populations of various mollusk
species have grown considerably and the last I heard was that the river
snail was everywhere and common in Enfield and elsewhere.

     With that being said, it is safe to assume the winter population of Common Goldeneyes will remain constant in Enfield for years to come. In an environment that is largely hidden, it is essential to annually monitor the health of the entire Connecticut River ecosystem. This will ensure that all living things, seen and unseen, will always flourish.