In the Northeast, sometime in September or October you realize that you’re no longer seeing American Toads. This is because they are taking steps that allow them to survive over the winter. These steps consist of either finding another animal’s burrow or digging their own (up to 20 inches or so deep) in order to hibernate below the frost line.
As the photograph illustrates, toads dig their tunnels facing forward, using their hind legs to do the digging. Special hardened knobs on their hind feet assist them in this endeavor. As they dig deeper, the tunnel in front of them collapses. When deep enough to hopefully avoid being frozen, they stop digging and hibernate until the soil begins to warm. Come April or May, American Toads dig their way up to the surface of the ground and head for breeding ponds. (Photo by Ashley Wolff)
American Dagger Moth (Acronicta americana) caterpillars are present from June to October in the Northeast, but because of their size (up to 2 ½”) and their searching for a suitable site to pupate in over the winter, they are very evident right now.
American Dagger Moth caterpillars have lemon yellow (early instars) or white (late instars) setae, or hairs. Their distinctive characteristic is the pattern of black tufts: two pairs of diverging tufts along the middle of the caterpillar and one thick black tuft at the end. As larvae they have a wide variety of host trees, including alders, ashes, birches, elms, hickories, maples, oaks, poplars, walnuts, and willows.
After locating a wintering site, these caterpillars will spin a cocoon in which they will spend the next several months as pupae. Late next spring American Dagger Moths will emerge from their cocoons as two-inch-long brown moths.
If touched, these caterpillars can cause a mild allergic reaction (a rash) in some people who touch the them.
The Northern Flicker is one of the few North American woodpeckers that is strongly migratory. However, most of the eastern migrants are Canadian breeders. They fly south from Canada with big flights moving down the Atlantic coast in the fall to the southeastern U.S.. Peak fall migration occurs from late September to early October, with some migration continuing to early November. As a result, New England sees an increase in the number of flickers sighted at this time of year. More southern populations are sedentary, and do not migrate. Northern Flickers that nest in New England do both. Some remain here for the winter, while some fly further south and return next spring to their northern breeding grounds.
Today is the autumnal equinox – night and day are of almost exactly equal length, twelve hours each. Each year there are two equinoxes and two solstices. Both signify a change of season, but they are very different phenomena.
The biggest difference between the equinox and the solstice is that an equinox is the point during the Earth’s orbit around the sun at which the sun is at its closest distance from the equator, while during a solstice, it’s at its greatest distance from the equator.
In September and March during the equinoxes, all areas of the Earth’s surface receive the same amount of sunlight. The September equinox marks the moment the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from north to south and vice versa in March. (Equinoxes are opposite on either side of the equator, so the autumnal (fall) equinox in the Northern Hemisphere is the spring (vernal) equinox in the Southern Hemisphere and vice versa.)
Solstice occurs when the sun reaches its northern or southernmost point (in June and December) — when its path is farthest from the equator. In the Northern Hemisphere the summer solstice happens in June, and in the Southern Hemisphere, the solstice happens in December (this is why the seasons are reversed in each hemisphere). So the winter solstice is the shortest day of the year while the summer solstice is the longest day of the year.
A new addition to my children’s book series on Animal Anatomy and Adaptations has just been released. Animal Eyes, Ears, Mouths, Tails, Legs and Noses are now joined by Animal Skins. This most recent book takes a look at how fur, feathers and scales help animals survive. (Suitable for children ages 4 – 9.)
Copies can be purchased from independent bookstores, online and from the publisher (go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on Animal Skins image on right).
This Woodchuck is doing what Woodchucks do this time of year – eating fast and furiously, and putting on fat equaling about a third of their weight (granted, an apple has only a tiny fraction of a gram of fat, but every bit helps). Accumulation of fat is essential if they are to survive months of hibernation. It’s not known what stimulates this increase in appetite, but most likely photoperiod (length of day) plays a part.
Soon these rodents will seek shelter in their winter burrows, where their heart rate is reduced from 100 beats per minute to 15 and their temperature drops from 96 F. degrees to 47 F. degrees. During hibernation, they lose roughly 20% to 47% of their body weight. Those Woodchucks not able to accumulate sufficient fat reserves may not survive the three or four months of hibernation that take place in the Northeast. (Photo by Erin Donahue)
Thanks to Pat Nelson’s sharp eyes, I realized I had mislabeled the bug in yesterday’s blog. It was an Ambush Bug, not an Assassin Bug. While both are predators and in the same family (Reduviidae), Assassin Bugs are usually dark colored and have long, narrow heads compared to Ambush Bugs. Ambush Bugs are usually quite stout and typically have bright colors such as yellow, red or orange. They also have thickened front pincer-like legs with teeth-like structures that hold the prey while it is being consumed. Although small (usually less than ½ inch), an Ambush Bug’s prey may be as large as a bumblebee, wasp or butterfly.