Natural Calendar April 2006

Natural Calendar - April 2006

The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month. We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips, prominent wildflowers and anything else that comes to mind. We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations. If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

Note: You can click on the hyperlinks to learn more about some of the featured items. To return to the Calendar, hit the "back" button on your browser, NOT the "back" button on the web page. All charts are available in a "printer friendly" mode, with black stars on a white background. Left clicking on each chart will take you to a printable black and white image.

Notes and Images From March 2006

Clockwise from upper left; Blooming Serviceberry, Cavespring Crayfish, Black Racer, Rock Overhang

All Images taken March 28th, Franklin Marion State Forest, Nikon D70

In March I helped with some wildlife inventory work in Franklin Marion State Forest south of Sewanee, Tennessee. Shown above are some of the images from that trip. The Cavespring Crayfish, Cambarus tenebrosus, is a common species in Tennessee. Seventy-seven species of crayfish occur statewide. The Carnegie Museum of Natural History has a very good web page on the crayfish of Tennessee at:

http://iz.carnegiemnh.org/crayfish/country_pages/state_pages/tennessee.htm

Sky Events for April 2006:

Pleiades Occulted by the Moon: On April 1st, be sure to get outside at dusk with a pair of binoculars and look for the crescent moon occulting the Pleiades in the constellation Taurus. This bright grouping of stars, also called the "seven sisters," should already be partially hidden by the moon at dusk and you can watch many of the cluster's stars reappear.

Lyrid Meteor Shower: The Lyrid meteor shower peaks in the early morning hours of April 22nd. Look to the east towards the constellation Lyra.

Evening Sky: Saturn is in terrific position for viewing this month, Look for it below the bright stars Castor and Pollux in Gemini. This is a great time to view this magnificent planet and most small telescopes will deliver a stunning view. Mars continues to fade in the western sky. It begins the month in Taurus and then moves into Gemini. On April 17th, binoculars should provide a pretty view of the red planet as it passes by the open cluster M35 in Gemini. The bright planet you see in the eastern sky in the early evening is Jupiter. It clears the eastern horizon about 8:50 CDT on the 15th.

Morning Sky: Venus continues to dazzle those early risers who view the eastern sky before dawn. At midmonth the goddess of beauty rises around 4:20am CDT.

All times noted in the Sky Events are for Franklin, Tennessee and are Central Daylight Time. These times should be pretty close anywhere in the mid-state area.

Constellations: The views below show the sky looking east at 9:00pm CDT on April 20th. The first view shows the sky with the constellation outlined and names depicted. Star and planet names are in yellow. Constellation names are in green. The second view shows the same scene without labels. New constellations this month in the eastern sky are Serpens Caput, the Serpent (Head), and Hercules, the Strongman. As spring progresses and Hercules rises higher in the sky, look for the globular cluster Messier 13 (M13), which appears like a small fuzzy patch of light about 1/3 of the distance between Eta and Zeta Hercules (see illustration below). A cluster of stars about 21,000 light years away, M13 can be made out with the naked eye in a dark country sky when the constellation is high in the sky. Binoculars help pick it out.

April 20th, 9:00pm CDT Looking East

On Learning the Constellations: We advise learning a few constellations each month, and then following them through the seasons. Once you associate a particular constellation coming over the eastern horizon at a certain time of year, you may start thinking about it like an old friend, looking forward to its arrival each season. The stars in the evening scene above, for instance, will always be in the same place relative to the horizon at the same time and date each April. Of course, the planets do move slowly through the constellations, but with practice you will learn to identify them from their appearance. In particular, learn the brightest stars (Like Arcturus and Spica in the above scene looking east), for they will guide you to the fainter stars. Once you can locate the more prominent constellations, you can "branch out" to other constellations around them. It may take you a little while to get a sense of scale, to translate what you see on the computer screen or what you see on the page of a book to what you see in the sky. Look for patterns, like the stars that make up the constellation Corvus.

The earth's rotation causes the constellations to appear to move across the sky just as the sun and the moon appear to do. If you go outside earlier than the time shown on the charts, the constellations will be lower to the eastern horizon. If you observe later, they will have climbed higher.

As each season progresses, the earth's motion around the sun causes the constellations to appear a little farther towards the west each night for any given time of night. If you want to see where the constellations in the above figures will be on May 20th at 9:00pm CDT, you can stay up till 11:00pm CDT on the April 20th and get a preview. The westward motion of the constellations is equivalent to two hours per month.

A good book to learn the constellations is H. A. Rey's classic, The Stars, A New Way to See Them. Rey's depictions of the constellations and witty commentary are terrific.

A good general reference book on astronomy is the Peterson Field Guide, A Field Guide to the Stars and Planets, by Pasachoff. The book retails for around $14.00.

A good beginners software program for learning the night sky is the Starry Night Beginner program. Visit the Starry Night web site at www.starrynight.com The program retails for around $30.00 and contains a wealth of information.

Circumzenithal Arcs: Fall, Winter and Spring are good times to watch for these beautiful arcs that form directly overhead. Be sure to look upward in the late afternoon anytime you have wispy cirrus clouds in sky.

Amphibians:

Northern Cricket Frog

With the warm temperatures this winter and spring, we've already heard Southeastern Chorus Frogs, Spring Peepers, Southern Leopard Frogs, American Toads, Northern Cricket Frogs, Pickerel Frogs and Cope's Gray Treefrogs. Pickerel frogs seem to have a sharp peak in calling at the end of March and the first of April. Around the beginning of April we usually hear our first American Bullfrogs, Green Frogs, and Fowler's Toads. Many of these species can be seen before then. The early calls of Gray Treefrogs sound raspier than the normal trill, as if the frog needed to clear its throat.

Birds:

The spring migration builds very quickly in April. The neo-tropical migrants are too numerous to list here, but now is the time to get out in the early morning with a pair of binoculars and welcome the new arrivals for the day. Listen at dusk for young Great Horned Owls and Young Barred Owls, doing their raspy "begging" calls.

Recommended:

Bird Finding in Tennessee, Michael Lee Bierly. A classic guide to finding birds in Tennessee.

The Sibley Guide to Birds, David Allen Sibley

The Sibley Guide to Birds of Eastern North America, David Allen Sibley

An inexpensive guide for beginners is the Golden Guide for Birds.

Wildflowers:

Some of our favorite Spring wildflower walks are:

The south ridge at the Owl's Hill Nature Center in Brentwood, Tennessee.

The Edwin Warner paved loop at the Warner Parks in Nashville or just about any trail in Warner Parks.

The greenway at Ashland City, Tennessee.

The Angel Falls trail along the Cumberland River at the Big South Fork Recreational Area, near Jamestown, Tennessee.