Explaining your interest in a favorite hobby or passion to the skeptical onlooker is a challenging task. A recent segment on National Public Radio’s “All Things Considered” led me to think about how I would do it.

The segment focused on the advent of spring and the subsequent emergence of birders in search of returning migrants. The one quote that stuck in my mind was from a perplexed man who had observed a crowd of birders watching a bird.

“The obvious response is – why?” he had asked. It sounded as if it made as much sense to him as watching paint dry.

I’d like to respond to this question by first stating the obvious: we watch birds because it’s enjoyable. Otherwise, you wouldn’t see so many of us out there – more than 70 million in the United States alone, according to The National Survey on Recreation and the Environment.

It gets us out in the fresh air, away from our computers, televisions, and everyday annoyances. I read a recent article by a woman who compared a bird walk to a session with a masseuse: seeing and hearing the birds helped her tired, overwrought mind to relax, and she returned feeling refreshed and ready to deal with the demands of her busy life.

It brings us into contact with other people who share our enthusiasm. And, of course, it brings us into contact with the birds we are seeking. Among all wildlife, birds as a group are the most easily seen and observed.

And what a diverse group it is. We delight in their beautiful diversity of form and function, surrounded by an aura of mystery. So much of their lives is unknown; their travels span thousands of miles across continents, across oceans.

They navigate these immense distances by ways we don’t completely understand, returning, in many cases, to the same nest hole or rock ledge where they were born. They are the ultimate symbols of freedom.

When we watch birds, we engage in an intellectual challenge to identify them, as we develop our powers of observation, intuition, and deduction. Call it the thrill of the chase, if you will; only we go equipped with optics instead of arms.

And the number of us that do this is rising.

According to the NSRE, the percentage of the population that engages in bird watching has tripled since the early 1980s, going from 12 percent in 1983 to 33 percent in 2001. It is one of the five fastest-growing activities in the country.

Many communities across the nation realize this and are attracting birders to their towns by developing serious birding trails. These birders bring business to local economies by spending money on transportation, hotels, restaurants, and souvenirs.

Which brings me to my final answer to “Why?” Watching birds means learning about their habitat requirements, which leads to appreciation and conservation of both bird and habitat through eco-tourism. This ultimately leads to a healthier environment for all of us – one that isn’t overrun with strip malls, housing developments, car dealerships, or big-box retail stores.

Chris Corio’s column on birds is published each Saturday. Corio, a volunteer at Fields Pond Nature Center in Holden, can be reached at fieldspond@juno.com