Recently, I was reminded of how fortunate I am to live in the Finger Lakes.
As wildlife-watchers there is much for me and my wife to see, with each season bringing its own special events in the life history of the animals around us. In June we watch for turtles laying eggs, birds eating our ripening mulberries and fawns becoming increasingly active in our fields and hedgerows. But our special wildlife treat in June comes as volunteers for the annual black tern nest survey in the Montezuma Wetlands Complex.
Black terns are listed as an endangered species in New York. I tell my students to think of the word endangered as meaning the animal is “in danger” of being lost. We sit right at the southwestern edge of their range and the terns nest in only a few places within New York. I should note that black terns nest in many other places and if we lost our residents the species could still be found elsewhere.
This species of tern likes to nest on floating mats of vegetation or muskrat lodges in marshes or other water bodies. The nests themselves are simple affairs — only a shallow cup to hold the eggs together. The speckled eggs are very well camouflaged and much pointier at one end than the familiar chicken egg. This allows the eggs to spin in a tight circle if they are disturbed rather than roll off into the water. We typically find nests with three eggs in them.
It takes about three weeks to incubate the eggs and another three or more weeks of feeding the hatchlings before they are ready to leave the nest. Mid-June is about the midpoint of that process and a great time to conduct a survey. The survey within the Montezuma Wetlands Complex covers both state and federal lands and is conducted mostly by canoe and kayak.
Laura and I were assigned to survey the southern half of the Main Pool at the Montezuma National Wildlife Refuge. If you are familiar with the Refuge, you may know that is the big body of water where the Wildlife Drive is located and the water itself is not open to public access. On the morning of the survey, we parked along the Drive and put our trusty old canoe in the shallow marsh. To ward off any questions, I leave a note on my window explaining that we are volunteers and add my cell number.
The survey is essentially simple: Head to the appropriate habitat and watch the birds’ behavior. It is like the childhood game of “hot or cold.” We spot black terns almost immediately. They are flying low over the water, searching for food. We can tell we are “cold,” not near a nest, because the birds are ignoring us. As we glide over the open water and approach the first stand of cattails, things change quickly. A black tern sails over us vocalizing loudly. We are getting “warmer.”
Laura sits in the front of the canoe and scans last year’s brown cattail stalks lying prone on the water’s surface. I use my paddle to put on the brakes and we drift forward slowly. Another tern has joined the first and soon there are more. Each bird is circling and squawking. We are “hot.” Laura spies a nest and we stop the canoe. There is no need to approach the nest closely or even to find every nest in the area. Once a black tern sounds the alarm that an intruder is near, all the other black terns in the area join in to help mob it and drive the danger away. Our job is to simply count the number of terns swarming around us and then move on to the next location.
We work efficiently so as not to disrupt the birds too much. Laura is in charge of the data sheets; as we count birds I use the large telephoto lens on my camera to capture images of the nest and the adult birds above. We find a second nest nearby as an adult we had not noticed suddenly loses her nerve and takes to the air. The number of birds swirling around us is probably a more accurate measure of the number of nests present than our eyes. As I mentioned, the eggs are very well camouflaged and we have no intention of weaving through a colony. We take a GPS reading and move off to the next likely location.
This process is repeated many times throughout the morning with carp, muskrats, osprey and painted turtles all pleasant distractions. As the morning wanes we find ourselves struggling with water too shallow to navigate and realize we have just about reached the end of our survey.
On our left we watch with envy as a great blue heron stalks prey easily in the slurry we cannot negotiate even with our canoe. Suddenly, the heron is surrounded by terns, all crying in agitation. The heron has inadvertently approached a black tern nest.
Although best known for eating fish, herons will eat a wide variety of prey including frogs, snakes and nestlings. Laura spots the nest before I do. One of the eggs has hatched and we watch as this hours-old black tern faces the first of many dangers. The adults are relentless in their annoyance and the heron quickly moves off, probably without even seeing the nestling who sports feathers as camouflaged as its eggshell was.
We dutifully count the mobbing terns, take a GPS reading of the location and officially call the survey to an end. As near as we can remember, our first black tern survey was in 1998. After 20 years, this annual rite has not gotten old.
Van Niel, an environmental conservation professor at Finger Lakes Community College, lives in Seneca Falls and enjoys exploring wildlife around the world as well as in his own backyard. If you have comments or questions, VanNiel can be contacted at firstname.lastname@example.org