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Autumn Leaves Color

While we don't know all the details, we do know enough to explain the basics and help you to enjoy more fully Nature's multicolored autumn farewell.

We do know the popular notion that Jack Frost causes colors is false!

Three factors influence autumn leaf color: (1) leaf pigments, (2) length of night, and (3) weather.

The timing of color change and leaf fall are primarily regulated by the calendar, that is, it is as unvarying as the steadily increasing length of night during autumn.

As days grow shorter, and nights grow longer and cooler, biochemical processes in the leaf begin to change. At this time, cells begin to form at the base of the leaf (petiole) forming a cortex layer, effectively sealing off the leaf from receiving nutrients.

A color palette needs pigments, and there are three types that are involved in autumn color.

• Chlorophyll, which gives leaves their basic green color, is necessary for photosynthesis, the chemical reaction that enables plants to use sunlight to manufacture sugars for their food.
• Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils.
• Anthocyanins, which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, and strawberries.

Both chlorophyll and carotenoids are present throughout the growing season. Most anthocyanins are produced in the autumn in response to bright light and excess plant sugars within leaf cells. During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As night length increases in the autumn, chlorophyll production slows down, then stops, and eventually all the chlorophyll is destroyed.

The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

Certain colors are characteristic of particular species. Oaks turn red, brown, or russet; hickories and ash, golden bronze; aspen and yellow poplar, golden yellow; dogwood, purplish red; beech, light tan; and black gum, crimson. Maples differ species by species—red maple turns brilliant scarlet; sugar maple, orange-red; and black maple, glowing yellow. Striped maple becomes almost colorless. Leaves of some species such as the elms simply shrivel up and fall, exhibiting little color other than drab brown.

The timing of the color change also varies by species. Oaks put on their colors long after other species have already shed their leaves.

The amount and brilliance of the colors that develop in any particular autumn season are related to weather conditions that occur before and during the time the chlorophyll in the leaves is dwindling. Temperature and moisture are the main influences. A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays.

Leaf color may also be influenced by insects in the plant, such as "flags" on sugar maple, soil chemicals and moisture.

—Joe Gray, 10/22/10

New Bat Booklet Available

Maine's Bats, a 12 page primer, compiled by chapter Conservation Chair Joe Gray, provides nearly everything a person might need or want to know about bats. Included are myths and facts, species description, what bats eat, housing shortage, box location, placement, maintenance and how to contact the chapter. Printing cost for the new booklet was funded, in part, by Camden National Bank, Oliver’s Print Shop, and this chapter.

Maine's Bats is available ($5 pp) at chapter events, programs, or by writing to:

   Mid-Coast Audubon Society
   P.O. Box 862
   Rockland ME 04842-0862

Bluebirds!
Erect a Mid-Coast Audubon nest box and they will come!

Here in mid-coast Maine we have been observing more Eastern Bluebirds each season and 2007 is no exception.

Inland, along many back roads through farming areas, we frequently see bluebirds on fences and power lines. For example, along the 8-mile long Route 213, Bunker Hill Road in Lincoln County, described by Down East magazine as "one of the prettiest roads in Maine," one may see no less than six bluebird families this year.

With 10 years' experience, Cornell's Birdhouse Network reports 60,000 nest attempts for 40 species that use nest boxes. Using more than 20,000 records, researchers found birds initiating later season nesting tended to lay fewer eggs and birds in northern latitudes laid more eggs than in southern areas, with both areas experiencing the same productivity.

Tree swallows were laying their eggs about 9 days earlier, possibly due to climate warming.

Bluebirds had the highest rate of hatching failure in warmer conditions. The Network also suggest other birds are laying their eggs earlier than in recent decades.

Even with pesticide use, nest box success on golf courses is higher than other habitats.

— Birdscope, Spring 2007

Importance of Bats in Maine

Maine is fortunate to have eight bat species, and much of the work of protecting crops, gardens, and backyards can be attributed to the Little Brown and other bats.

Bats are Maine's greatest resource in controlling insects, since a bat may consume half its weight—or as many as 2,500 insects—in a single night.

They are year-round residents of Maine. Although not active in winter, bats can be found in every Maine town, snugly resting next to a warm chimney, often without the home owner's knowledge of their presence.

Maine has plenty of flying insects from May through September but there is a housing shortage for bats.

That's where Mid-Coast Audubon—and you, too—come in. Chapter members produce bat boxes designed for our latitude and made from native white pine at an affordable cost of $15.

We make the boxes—you put them up! Almost everyone has a suitable location for one or more bat boxes. Bat boxes should preferably face west, mounted at least 10 feet above ground and free from obstructions below the box.

Bats forage widely over garden areas, open fields, streams, wetlands, and ponds. All are desirable habitats.

Get a bat box from Mid-Coast Audubon by calling (207) 563-2930 today.

For more information about bats, call John at (207) 563-2930 or Joe at (207) 563-3578 and ask for a copy of Mid-Coast Audubon's newest publication Maine's Bats ($5 pp).

Suet Log Feeders Bring Birds

Extra energy is found in suet and woodpeckers, chickadee and nuthatches know this and supplement their seed diet with suet.

Mid-Coast Audubon Log Suet feeders are easy to fill with suet and bring birds.

Call John Weinrich at (2087) 563-2093 and arrange to pick up your log suet feeder ($15) today.

Mid-Coast Audubon is now an affiliate member of the North American Bluebird Society (NABS) and membership for Chapter members is $15 when you specify "Special A+ Offer Applies." Membership brings the quarterly Bluebird magazine, the journal of NABS, filled with information about conservation, research, education and promotes the recovery of bluebirds and other cavity nesting birds. Write: NABS, P.O. Box 45, Miamiville, OH 45147.

Revised 01 August 2007

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