Migration Sheds Light on Factors Affecting Bird Abundance

We’re in the midst of fall migration, when masses of birds descend on our forests, farms, wetlands, lakes and shores to find shelter and refuel for their journey further south or to hunker down and settle in for the winter.
August through November is truly stunning in New Jersey.
Take for example, the Avalon Seawatch, which New Jersey Audubon’s Cape May Bird Observatory has been conducting since 1993. Each year, between Sept. 22 and Dec. 22, we tally upwards of 800,000 migrating water birds including ducks, gannets, cormorants and more.
The majority of this count is made up of ducks; imagine seeing nearly 70,000 Black Scoter streaming past Avalon (Oct. 26, 2007 record) or more than 13,000 Red-throated Loon passing by (Nov. 24, 2015 record). The migration spectacles witnessed here each year are almost too numerous to count!
To celebrate the spectacular migration phenomenon, the Cape May Bird Observatory hosted the longest running birding festival in the country (Oct. 19-22).
The shape of the Cape May peninsula funnels the birds into a smaller geographic area where they typically pause to rest and feed before crossing the Delaware Bay on their southward journey, providing a visual feast for thousands of spectators.
While many species observed breed right here in the Garden State, during the spring and fall we are treated to sightings of species that only pass our way once or twice a year or whose numbers increase substantially during migration.
The Blue-winged Teal is one such species. A small duck classified within the group that “dabbles” on the water’s surface by tipping its head down to feed and leaving its bottom exposed, this species is most easily identified by the striking white crescent moon pattern on the face of the male, although it is the more difficult-to-observe patch of blue feathers on the upper wing that give the species its name.
While many species are more rare or unusual, and thus actively pursued by birders, this is one species that connects us to a region we don’t often consider when thinking of “our” bird migration.
The Blue-winged Teal is a long-distance migrant that breeds in small pockets in northern and southern New Jersey but in much larger numbers across large portions of the central U.S. and Canada, with the Prairie Pothole Region being particularly important.
This region, a valuable prairie-wetland ecosystem spanning across Montana, North Dakota, South Dakota, Minnesota and Iowa, is considered the most important breeding habitat in North America for waterfowl such as Blue-winged Teals, as well as other species that pass through or spend the winter in New Jersey like Northern Pintails, American Black Ducks, and Canvasbacks.
Bands placed on birds’ legs help identify migration patterns and recoveries in New Jersey have shown that Blue-winged Teal, American Black Ducks, and Mallards are migrating from the Prairie Pothole and Great Lakes regions, connecting us to these landscapes that would otherwise seem distant to our mid-Atlantic coastal state.
Between 2008 and 2012, more than seven million acres of grassland and other habitats across the Midwest were converted to agriculture. In a two-year timespan, 3.2 million of these acres were plowed and drained in the Prairie Pothole Region, in large part to meet demand for corn ethanol production to satisfy Renewable Fuel Standard requirements.
While New Jersey is not a significant corn-producing state, the conversion of native prairie to produce corn ethanol impacts us. While I lead tours to areas of the Midwest where the scale of this land conversion is plainly evident, migration is a reminder that the nearly sole dependence on corn to meet Renewable Fuel Standard goals is leading to irreversible harm to unique prairie and wetland habitats known as our nation’s duck production factory.
The federal Renewable Fuel Standard began with good intentions to reduce greenhouse gas emissions and dependence on imported oil by requiring petroleum-based fuels to be supplemented with renewable plant-based fuels. The program is harming our nation’s wildlife and requires reform.
Therefore, birdwatchers, hunters, conservationists and frankly all New Jersey citizens that enjoy the sight of ducks dabbling or diving on their local shores, lakes and ponds should encourage reform of the Renewable Fuel Standard.
This doesn’t mean the abandonment of biofuel goals, but limiting the share of ethanol made from corn to meet renewable fuel targets is one place to start. Letting your congressional members know that you support efforts to limit native prairie and wetland habitat destruction for the Renewable Fuel Standard is one great way to help maintain the spectacular migration season we enjoy in New Jersey.
ED. NOTE: La Puma is the director of New Jersey Audubon’s Cape May Bird Observatory.