Red Maples

I find Autumn phenological observations a bit more difficult than spring phenology. The first Tree Swallow is the first Tree Swallow. It is a little harder to observe when the last Tree Swallow departed. Even for autumn arriving birds, things seem a little more complicated.

I saw the first Dark-eyed Junco at our feeder at the Osprey House at Lehigh Gap (northern Lehigh County) on 27 September, but it was only one or two at a time and was likely juncos visiting our feeders from high up on the ridge where they seem to be breeding in very small numbers. I didn’t see any juncos at my feeder near Lehighton in Carbon County until 24 October and saw large numbers of juncos at Lehigh Gap on the same date.

Then there are the Red Maples. (By the way, maples that are red all summer are not native Red Maples, Acer rubrum. Those are either Japanese Red Maples or a variety of Norway Maple called Crimson King.) I started seeing a few red/orange/yellow leaves on Red Maples at my home in early September, but most of the leaves on most of the trees were still green.

There is a great deal of variation in Red Maple colors and phenology – some turn early, some late. Some turn yellow, others orange, still others bright red. Some are almost bare while others retain most of their leaves with some still green. So I decided to select two Red Maples and photograph them every few days throughout their color change. I did not know what was going to happen.

The two trees, both in my back yard, and are from different genetic stock. One was planted as a sapling after a friend received it in the mail in return for a donation he made. The other grew up naturally from seed. We will call the imported sapling tree “A” and the local tree “B.” A is on the left of the photos where both are shown, B is on the right.

Here is what both trees looked like on 30 September. Both trees are still very green, but the local Red Maple B (on the right) is beginning to show some autumn color.

By 10 October, B is showing lots of red leaves, while A is still green.

Meanwhile there were other local trees that had lost most of their leaves already, including this one near my yard that had turned yellow. (10 October)

By 17 October, tree B was nearly completely colored while A was still nearly all green.

In just three days, tree A had turned yellow, while tree B was orange (20 October).

By 23 October, B was past its color peak and tending toward brown, while A was still at its peak of yellow.

Here are two other Red Maples in my yard on 23 October – one almost bare and the other bright orange. And here is another specimen that was still partly green on that same date.

One week later, a freak early blizzard hit us and that was the end of the leaves on both tree A and B. Here they are on 30 October, the beautiful sunny morning after the Nor’easter.

(That's snow all over the ground!)

A discussion with Diane and Corey Husic on Saturday led to an investigation we will pursue next year. Red Maple flowers have similar color variation in spring as the leaves do in autumn. We wonder if trees with red blossoms have red leaves, and those with yellow blossoms have yellow leaves in fall. Stay tuned -- or do the investigation yourself and let us know what you find.