By Robert M. Ungerer
Two weeks ago, my friend Ranjit Laha and I traveled to Cape May, N.J., a famous fall bird migration site. We participated in daily field trips starting at 7 a.m. led by Cape May Bird Observatory (CMBO) experts. During the weekend I saw four never seen ''life birds.'' The most spectacular species for me was the merlin falcon, which happened to be very common on this migratory route.
Sometimes the ways of nature which we often do not understand seem cruel. Take the cases of raptors (hawks that eat mammals and birds), like the peregrine falcon and Cooper's hawk, which may raise young in Ontario, Canada, or northern New York then migrate south leaving their young on their own to travel south weeks later. Scientists have discovered birds navigate by a combination of star configuration, the earth's magnetic field, and landmarks on the ground such as mountain ridges. One such famous pathway, Hawk Mountain, west of Allentown, follows the mountain ridges in eastern Pennsylvania. The young raptors called juveniles, migrating at night, start out over land but do not realize they must stay over the ridges. When a strong west wind blows, the young raptors get blown over the Atlantic Ocean. At daybreak, they find themselves lost over water with no place to rest or find food. The raptors turn around, flying north to find land, in this case, northern New Jersey or Long Island, N.Y. They reorient themselves and proceed south again along the shore of New Jersey, funneling directly over Cape May at the southern tip of the state on their way to southern states or Mexico. Hawk watchers stand on wooden platforms, binoculars in hand, counting raptors every day September through November.
A young naturalist demonstrates a juvenile raptor before releasing it at Cape May State Park.
Photo by Robert M. Ungerer
The New Jersey Audubon Society established the Cape May Bird Observatory to study bird migration and educate the public. Counting birds is like taking a census; the results help naturalists determine if a species is declining in number or whether it has a healthy population. Data revealed the kestrel falcon declined from 260 in 1975 to 63 in 2003 while bald eagle numbers rose from 56 to 506 during the same time. Taking a census of birds is easiest when birds can be observed funneling over selected sites like the narrow land at the tip of Cape May sitting on a hawk watch platform. The alternative is to count birds on their nesting ground, searching through woods and mountains across thousands of miles.
To study migrating raptors, they are trapped, size, sex and species recorded and a numbered metal band placed around the leg, before release. Later, if this raptor is found dead or recaptured, the banding information can inform one how far the bird traveled and its age since the initial banding. Raptors are captured two ways: one is in a mist net strung up in a flight path close to the ground and the other is with live birds like English sparrows and pigeons as bait. Leather jackets are placed around these bait birds and attached to a leash. When a passing raptor strikes, the leashed bird is pulled into a cage with the raptor. I was told the stunned bait birds usually recover to serve again.
On Saturday morning the CMBO staff captured two raptors which they banded, demonstrated to 50 onlookers including us and released promptly. The captured raptors, both juveniles, confirmed the finding that 70 percent of migrating raptors at Cape May are ''lost juveniles'' blown off course.
Cape May, originally a fishing village, is surrounded by the Atlantic Ocean, so sea birds are common. A young gentleman we met from CMBO was assigned to watch over the Atlantic Ocean from sunrise to 5 p.m. daily, counting sea birds. He helped me identify two different large terns and three sandpiper species.
Cape May is an eight- to nine-hour automobile trip from Jamestown, hotel rooms off-season are reasonable, restaurants are plentiful and the bird watching is spectacular. Consider a visit there next fall to sightsee or bird watch.