Answering the Question of 'What is a Rare Bird'

There are many species of birds living in our region that most people never see. Then there are some that they might see once, and wonder. "Is this a rare bird in my yard?" If they know someone who is a bird person or birder, they will call and ask the question. How does one answer this question?

The pileated woodpecker is often the species at issue, because it is large and obvious, and sometimes comes to a suburban yard. Normally it stays in the deeper woods, which provide enough ant-infested trees and dead snags for food and nesting sites. This woodpecker is as large as a crow and a single bird or pair needs plenty of these trees to keep it alive.

There is enough mature forest in our area to make this woodpecker a resident, but not enough to make it as common as a chickadee. However, it is not a rare species. A rare species would be one that is truly out of place or time. It is common somewhere else or at some other season, but not here and now. The pileated woodpecker is as common here the year round as it is anywhere.

The brown pelican or the spotted towhee, which have both been found in our area this winter, are examples of rare birds. They are extremely rare, species seen here once in a lifetime, and normally present only far to our south and west respectively. There are many other species that are rare, but regular. They are seen in most years by someone who goes into the field often to search for birds, but never more than a few times each year.

The northern shrike or Lapland longspur are examples of such rare but regular species. They are both much more common to our north and west, nesting on the Canadian tundra and spending the cold months in the unforested country of southern Canada and the northern United States.

They are seen often enough to place them in the list of about 250 species that occur regularly in western Massachusetts. In the calendar year 1999, I was able to find only 216 of these regular species in the four western counties of Massachusetts. In 31 years of searching, the most I have ever located in a year was 240 species.

In every case, what makes a species rare and what makes them a challenge to find, is migration. Birds have an instinctual drive to move long distances in response to seasonal change and the availability of food, and this means some of them will move off course. Even more will move a bit too much or too little.

The two examples of the shrike and the longspur are birds that migrate south in the cold months and have come farther south and east than most other shrikes and longspurs. Only 50 of the 98 species that are regularly found here in the three winter months are within their normal winter range. Of these fifty species, twenty are sedentary, they do not migrate at all. That leaves only thirty species for whom we are a migratory destination in winter.

That means forty-eight species are here by mistake or forced by dire necessity. Of these, fifteen should be farther north, twenty-seven ought to be farther south, and six should have retired to our coastlines. These numbers do not include species that are extremely rare in winter.

In the winter season of 1999-2000 I have observed 77 species since December first, the same as I saw in the entire winter of 1998-99. My most ever is 91, and my goal some year is to reach 100. Perhaps the year 2000 will be the year.

Speaking of this special year, on January first I started my year list, and when darkness came on that day I had 23 species. During a trip to Hadley the next day I added thirteen more, including the spotted towhee. It was the first time I had ever seen this species in Massachusetts, my 373rd state life bird. Two days later the brown pelican made it 374 species observed in Massachusetts. It is a good start to a special year.