Thom Smith | Naturewatch: Do robins feel worms moving or hear them?

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Q: I have wondered for many years how robins find earthworms. Do they feel the vibration from worms or do they hear them?

— Dave K. Pittsfield

A: American robins ignore earthworm vibrations and any noise that they may make, but rather use their eyesight to detect earthworms, and other invertebrates particularly in spring and summer.

The next time you see a robin on the lawn notice how it first cocks its head to the side so that it can better scan the ground searching for an earthworm. Having monocular vision, they don't see by looking forward as we and owls do. Experiments have shown that a dead earthworm in a hole will be seen and eaten by a hungry robin.

"The early bird gets the worm" is true in the case of the American Robin (except following rain), as later in days with little or no precipitation as the sun warms the ground and dries the morning mist, earthworms and night crawlers retreat to cooler and moister soil out of reach of the hungry robin.

Q: How common are mergansers in the Berkshires? On the Housatonic River last Friday, I watched a male and two females fishing and diving their way upstream. I have never seen this kind of duck before, so the flashy black-and-white male was especially a bright surprise to me. Their behavior reminded me of loons.

— Emily, Pittsfield

A: Common mergansers arrive in the early spring and may be seen into May, and again in early fall through the freeze-up of lakes. And while they are considered migrants, a few remain on the Housatonic and Hoosic rivers during the winter. This is also true on the Farmington and Deerfield Rivers with occasional nesting occurring. Without verifying, I would suspect the same occurs along the Connecticut River.

These diving ducks incidentally, are in an entirely different family than loons, although they share some of their behaviors.

The hooded merganser is an interesting relative that until the late 1970s was described as a migrant, but during a scant 10 years became a fairly common summer resident as well, and found nesting in about 25 percent of wood duck boxes.

Alien invaders, Part 2

Many of the early aliens arrived with the blessings of the colonists and early settlers who brought their favorite plants from their kitchen gardens, either because of their ornamental or sentimental value or because of their medicinal values. They brought plants they used in every day usage for dyes, spices and favorite herbs and on and on. Slips and seeds of fruit trees were among the first to reach our shores.

There would be no problem, if all of these imports stayed where put, and if unknown species or unintended gatecrashers didn't also arrive. And we can't really blame all of our present problems on the settlers. Through the years, more and more plant species (as well as insects and a few birds and mammals) made it to our shores on purpose or unknowingly

As our world continues to get a little smaller because of the speed and ease of travel from continent to continent, alien plants continue their expansion.

One major nuisance today in numerous watersheds is the water chestnut, as interesting (and illegal) as it may be in local garden ponds and pools, it is literally spreading rapidly and congesting ponds, lakes oxbows, coves and any still or slow-moving shallow water.

It was introduced to Massachusetts around 1874 in the Harvard University Botanic Garden. Staff gardener Louis Guerineau took it upon himself to throw seeds into Fresh Pond and other Cambridge waterways, and from there it was encouraged elsewhere. As early as 1879, concern was voiced by Charles Sargent, director of Boston's Arboretum that this non-native threatened to become a nuisance. It has done so and more. Today, it has been declared invasive from Vermont to Virginia.

Thom Smith welcomes your questions and comments. Email him at Naturewatch@live.com or write him care of The Berkshire Eagle, 75 S. Church St., Pittsfield, MA 01201.


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