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We’ll be celebrating our nation’s independence on Thursday, the Fourth of July — a day of fireworks, barbecues, parades and a big road race. For the natural world, July 4 also will have special significance.
For starters, the day before Independence Day is generally regarded as the traditional start of the dog days of summer, although the actual start date may be disputed by some sources. The 40-day dog day period is supposedly the hottest, muggiest part of the year. (I can’t imagine, though, it being any hotter than what we’ve already experienced so far this summer.)
To ancient Greeks and Romans, the dog days were linked to the Dog Star Sirius and its daily rising and setting with the sun. The combined effects of Sirius and the sun, the ancients believed, were responsible for the sweltering heat, drought, sudden thunderstorms, lethargy and mad dogs in July and August.
Scientists have determined Sirius really has no effect on Earth’s weather and searing summer temperatures. Southerners, though, have their own dog day beliefs. For one, some believe that snakes — even the nonvenomous ones — are more aggressive during the dog days and will deliberately attack humans.
There’s no truth to that. It is, however, prime egg-laying time for several snake species, including corn, rat, Eastern hognose and rainbow snakes.
For many of us, July 4 also marks the date ruby-throated hummingbirds start returning to feeders. A rule of thumb is that hummingbird migration begins after July 4. Ruby-throated hummingbirds — nearly all of them males and juveniles at first — will start coming back to feeders to fatten up for their arduous trek to winter homes in Mexico and Central America.
The reason so many males show up in the early going is that most females — alone and without the males’ help — are still tending their nests. Two broods of ruby-throated hummingbird babies are usually produced each year in Georgia, the first in late April or May and the second in late June to early August. After the young fledge, they and their mothers also will start coming to feeders to store up energy for the long journey south.
IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be new on Friday (July 5). Mars, Jupiter and Mercury are in the east just before sunrise. Saturn rises in the east about three hours before sunrise.
Charles Seabrook can be reached at charles.seabrook@yahoo.com.
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