An online resource based on the award-winning nature guide

Sexual Dimorphism

Common Green Darners Migrating

9-16-13 common green darner 249The Common Green Darner, Anax junius, is one of our largest dragonflies, measuring three inches long, with a four-inch wingspread. It is strikingly colored, with a green thorax and a bright blue (male) or reddish (female) abdomen. As if that weren’t enough to set this dragonfly apart, it is also migratory. Common Green Darners migrate south from August to November, stopping over (like migrating birds) occasionally along the way, resuming flight after resting and refueling. Thanks to radio telemetry, we now know that over a two-month migration, Common Green Darners, each weighing about one gram, can migrate over 400 miles. (Photograph is of a Common Green Darner perched on Bottle Gentian.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


A Frog’s Tympanum

8-15-13  green frog tympanum  051A frog’s tympanic membrane, or tympanum, is the circular patch of skin directly behind its eye that we commonly call its eardrum. It functions much like our eardrum does –the tympanum transmits sound waves to the middle and inner ear, allowing a frog to hear both in the air and below water. In addition, this membrane serves to keep water and debris from entering a frog’s ears. In some species of frogs, such as the Green Frog, American Bullfrog and Mink Frog, their gender can be determined by the size of their tympanum relative to their eye: the male’s tympanum is larger than its eye, the female’s is equal in size or smaller than its eye.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


A Great Christmas Present!

If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill.  A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!

One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”

In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e  book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”

I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!


Autumn Meadowhawks Mating

Meadowhawks are the only small red dragonflies seen in New England (most males are red, most females are brown).The latest species of dragonfly flying in the fall in this area is the Autumn Meadowhawk (Sympetrum vicinum), which doesn’t emerge until mid-summer. It seems a bit incongruous to observe these dragonflies not only flying, but mating and laying eggs in late October, but that is exactly when you can expect to see them. Until there have been several hard frosts, these winged masters of the air are able to keep active by basking in the sun and warming their flight muscles. The two pictured Autumn Meadowhawks are copulating in the typical “mating wheel” fashion, with the male grasping the female behind her head while the female places the tip of her abdomen at the spot on his abdomen (the seminal vesicle) where he stores his sperm. The female Autumn Meadowhawk lays her eggs in tandem with the male (his presence prevents other male meadowhawks from replacing his sperm with their own).


Twelve-spotted Skimmers

Twelve-spotted Skimmers are classified as “King Skimmers,” all members of which are large and conspicuous, often with distinctive wing patterns.   Male Twelve-spotted Skimmers (pictured) have a grayish bloom on their abdomens and each wing has three dark spots with white spots in between them.  Females have brown abdomens and no white spots on their wings.  All summer you can see males flying back and forth short distances along the shores of ponds and over water, hovering as well as perching.  They are territorial and patrol over water, loop-de-looping with competing males.  A small number of Twelve-spotted Skimmers occasionally take part in Atlantic Coast migrations.


Eastern Tiger Swallowtail

The male Eastern Tiger Swallowtail butterfly (pictured) is yellow with four “tiger stripes” on each of its forewings. The female can be yellow or black, and has more blue on the hind wings than the male. Eastern Tiger Swallowtails are currently mating and laying eggs on plants which their larvae eat, which include black cherry, red maple and American hornbeam. When the caterpillars first hatch, they resemble bird droppings – an effective way of decreasing predation. As they get older, the larvae turn green and have a large head and bright eyespots.


Hooded Mergansers

A few hooded mergansers, small fish-,insect- and crayfish-eating ducks of wooded ponds,  can be found year round in northern New England, but their numbers swell in March and April, when many migrant birds return to breed, and  others  stop over on their way further north.  Standing dead trees, or snags, provide nesting cavities for these beautiful, “hammerhead” crested ducks. (Male hooded merganser on left and female on right in photograph.)


Follow

Get every new post delivered to your Inbox.

Join 2,893 other followers