NUMBERS OF MIGRANTS MIGHT EVEN BE UNDERESTIMATED  

Thursday, May 26, 2011

In In past columns, I have often commented on a medical condition, known as S.A.D. (Seasonal Affective Disorder) brought on by a combination of shorter days, cloudy conditions and rainy weather. I have always claimed that, as a naturalist, I don't suffer from it since I am far too busy enjoying the natural world and accepting the weather as it comes, for it to be a concern.

However, after last week's dismal, rainy weather, during which the sun rarely peeked out from behind a perpetual ceiling of dark, water logged clouds, I was ready to give this S.A.D. thing another chance. It did take everything in my being to greet each day with an optimistic smile as I guided visitors along the network of walking trails in this remote corner of Prince Edward County that has always meant so much to me.

This was Prince Edward Point, more specifically, Point Traverse, where volunteers who work with me have created a network of trails through a predominantly ironwood/hickory forest. The trails are there to guide members of the binocular brigade every spring into sections that are known to harbour spring migrants. For this is the tip of the Long Point peninsula, long recognized as a rival to famous Point Pelee. If conditions are favourable, the peninsula will get dumped on by thousands of migrating songbirds, exhausted and hungry after crossing Lake Ontario. For most, it has been a perilous journey and, for some, a long one, from as far away as Brazil and Central America. This is just a refueling station for some like the majority in the warbler family who will journey on to the boreal forests of Canada to nest.

For anyone whose knowledge of migration dynamics extends no further than the backyard bird bath, the enormity of their numbers can be difficult to comprehend. Bird monitoring and banding carried out every spring and fall suggest that their numbers approach a million. During the day, they are counted and thousands are banded under the auspices of the Prince Edward Point Bird Observatory, a facility that soldiers on using volunteers and no government funding. However, what are actually seen and counted are but a mere fraction of what really occurs.

Since migration of passerines takes place during the night, we cannot see the real numbers, but sophisticated radar systems present the true picture for us. The Bird Observatory uses the NEXRAD (Next-Generation Radar) site located near Watertown, New York. This function allows us to see the direction and speed of birds moving over the area. It shows masses of migrants approaching the Prince Edward County shoreline in the millions where they descend and commence exploiting the rich habitat for insect food. Gradually, they work their way down the shoreline toward Prince Edward Point proper where they congregate in huge numbers as they again wait for the right conditions before crossing Prince Edward Bay. One problem with radar is that low flying birds often go undetected. Prince Edward Point is situated at the edges of two radar sites (Buffalo and Watertown) and often birds flying at 300 feet or lower are below the radar's ability to detect them. The actual mass of migrants could, in fact, even be grossly underestimated. 

Do, they take advantage of a natural chain of islands extending from New York to Main Duck Island, then to Prince Edward Point? Some do for sure, as I  have  seen small "fallouts"  of migrants on Main Duck Island myself, and have actually stood along the cliff edge at Point Traverse as huge numbers of rose-breasted grosbeaks descended on me, having obviously taken this route. During boat tours to Main Duck Island in past years, however, I have seen nothing to suggest that this is a preferred route; the habitat just isn’t there on any of these islands to support significant numbers of migrants. Mostly, it is a wall of birds that drops from the skies all along the remote south shore of the county, from Sandbanks, all the way to the tip of the peninsula, and the radar clearly show this taking place. It cannot be disputed.

For blue jays and birds of prey, it is a different story. Last week, through rain speckled binoculars, we saw columns of blue jays migrating, but avoiding the water. They prefer following land masses during their migration, avoiding the water as much as possible, following the shoreline along and, in the case of raptors, the thermals, as they make their way along to their destination.

During last week's Birding Festival, there were no fallouts; an unfavourable wind direction had stopped them in their tracks on the New York side, but a few had managed to make it across. During the guided tours we were seeing pretty much the same species, in the same numbers, each day. They were beginning to recognize me, I think, and responded to our presence. But, new ones kept showing up. One day, in a persistent drizzle, at least a dozen great crested flycatchers showed up, where before there had been none. Another day, it was a Wilson's warbler, and a Swainson's thrush. By the following weekend, others were chancing a lake crossing, eager to reach the boreal forests and start nesting. Absent that week due to unfavourable northeast winds were the major fallouts when migrants literally hang from the tree branches. On days like that, one just remains in selected spot, and revels in the spectacular migration that is Prince Edward Point. Those are days that keen birders dream about, even in the rain.