Archive for the ‘Natural history tidbits’ Category
Let a Sleeping Bear Lie
Friday, January 29th, 2010
Black Bear Mom and cub in den
As I sit here on this blustery, bone-chilling January day, I cannot help but think about how black bears are faring. Snoozing away in their dens, I hope their fat, fur and den location helps fend off the negative-degree wind chill.
Pregnant females are more picky than males in selecting a den. If large trees with cavities are available, that’s high-rent district right there. If not, then under a windfall, brush pile, or a rock crevice will do. A suitable den provides safety from predation and protection from the elements. It should not be much bigger than the size of a curled up bear. Don’t expect to see a bear huddled up in a cave – too much space and not enough security.
Females are in dens by mid December and males by mid January in the southeastern US. In more northern latitudes, make this a month or so earlier.
Black bears are too big to hibernate. If you want to be accurate, call a bear’s winter sleep “carnivorean lethargy”. If a bear’s body temperature were to drop to the extent a true hibernator’s does – a few degrees above freezing – it would require too much energy to bring all that bulk up to normal again. Heart rate decreases only slightly, as does breathing, so a bear is quite capable of responding if disturbed. I would not advise poking a groggy bear in its den. He’s likely to poke you back.
Although a bear’s gastrointestinal tract shuts down completely, a bear still consumes between 3,000 and 4,000 calories a day during their winter inactivity. This comes from their store of fat. If only I too could sleep my fat away and wake up slim and trim. Another enviable ability is their lack of deterioration of muscle and bone during months of inactivity. You and I would experience extensive bone loss and muscle weakness should we lie still for that long. In the spring, bears give a stretch and a yawn and off they go to find something to eat.
So, you go bear. You’re adapted to this merciless weather. I’ll just continue to sit inside my heated home on this January day, exercise, breathe normally and eat all winter long.
How Animals Sleep – Fun Facts from the Animal Kingdom.
Saturday, November 14th, 2009
Sleeping Sea lion
Been getting enough sleep lately? Chances are, those 8 recommended hours are elusive at times, if not frequently unobtainable. The other night while I lay awake, unable to stop those chugging brain cogs, I wondered about the sleep requirements for other members of the animal kingdom. Do other animals require so much sleep? How do they sleep? Do they dream?
The next day I perused a book called, “Sleep and Rest in Animals” by Corine Lacrampe. It is not an in-depth comprehensive approach to the subject, but rather gleans some scientific results and lays it out for recreational reading. It has a beautiful collection of sleeping animal photos too. From it I gleaned some curious tidbits you may find interesting to contemplate the next time the sandman eludes you:
Birds
* Perching birds have a mechanical locking system to stabilize them when asleep. Tendons cinch toes closed and the femur connects with the pelvis to lock legs in place so they don’t fall off their perch.
* Birds, like humans, experience REM (rapid eye movement) sleep, indicating dreaming is going on. No REM sleep has been observed yet in reptiles or amphibians.
* Some birds can rest one of their two brain hemispheres at a time. Half the brain gets deep sleep and the corresponding eye is closed (the eye on the opposite side of the head), while the other half of the brain is alert to danger with an open eye.
* Of the birds studied for sleep, very short REM cycles are recorded, mostly 10-20 seconds; but many throughout the day – as much as 200 in a 24 hour period.
* Swifts are one of a few birds that can catch a few winks while on the wing. Getting 3,000-6,000 feet above a pocket of warm air, a swift flaps roughly every 4 seconds, then glides for 3 seconds as it snoozes. Penguins also have been found to sleep in brief stints while they swim during long migrations. They wake regularly to breathe at the surface.
Reptiles/Amphibians/Fish/Insects
* Crocodiles sometimes rest with open mouths for heat regulation. Vessels there are nearer the surface. Letting the sun shine in makes for faster warming if it is cool and sunny. If the croc is too hot, it allows heat to dissipate quicker.
* Sea turtles sleep, eyes closed, head rested for brief periods of time on the seabed. It must wake to come up for air.
* Outside of brumation (reptilian hibernation) it is hard to say if snakes sleep. But they sure can sit perfectly still for many hours at a time.
* Sharks sleep. Contrary to popular belief, they can lie motionless on the ocean floor for a time. Divers have even reported gently touching them without waking them.
* Tree frogs sleep. The green treefrog turns a tan color when napping.
* Insects don’t experience the same type of sleep mammals and birds do. They do however rest in various ways. The jewel wasp naps, with head folded and antenna tucked. Moths wait out the day motionless on trees, to which they may be quite camouflaged.
Mammals
* Koalas are super sleepers. They snooze about 18-20 hours per day tucked up in the branches of a tree digesting eucalyptus leaves.
* In relation to some other primates, our requirement for sleep is small. But like us, our closest relations sleep in one long stretch at night. Baboons and chimpanzees average about 10 hours of sleep; gorillas about 12 hours and orangutans get about 14 hours of sleep each night.
* Many mammals don’t sleep in one long stretch like us. The elephants’ daily cumulative sleep is about 4 hours; Giraffe, 2 hours; Okapi only 5 minutes of sleep per day.
* The dolphin sleeps for 7 hours, but like birds, only one hemisphere at a time. In this way it can keep swimming and coming to the surface to breathe while it is sleeping. Unlike birds and most mammals, no REM sleep has been detected in the dolphin.
A Parasite in the Woods – Beechdrops
Saturday, November 14th, 2009
Beechdrops
I went for a hike this morning along one of the Hilltown Land Trust’s beautiful trails in my area. The Steven’s Trail is fairly new. Some limb clearing had to be done, but the trail was well marked and easy to follow. It went from dark hemlock stands to lighter hardwood forests, winding around boulders of granite covered with moss, lichen and rock tripe. Great hike.
Where beeches were prevalent, beechdrops were growing at their feet. Beechdrops are an interesting plant. Totally parasitic, they contain no chlorophyll so have no green color. They obtain their nutrition from the roots of their host tree: American Beech. Their leaves are not readily noticeable; they are little scales along the branching stems. The curved trumpet-like flowers, which may be reddish/brownish/yellowish stick out all along the branches. Beech drops have only since August become large enough to be noticed and are blooming now. At any given time, only some of the many flowers along the branches are in bloom. Other flowers are in bud while others are finished blooming and working on their seeds if they’ve been pollinated.
Beech drops are a plant of eastern US, from as far north as the Gulf of St. Lawrence down to Florida, and west as far as Louisiana.
What makes Autumn Leaves Turn Crispy Red?
Saturday, November 14th, 2009
Red maple leaf in the fall
The air is crisp. Apple crisp is baking in the oven. Leaves will soon be crispy underfoot in the deciduous forest. For now, the color show marching southward from Acadia National Park along the Appalachian chain, through Shenandoah National Park and on into the Smokies offers us an effective diversion from thinking about the impending crisp winter weather to come.
Some years here in New England, the show is simply acceptable, and others, absolutely spectacular. Those trees that turn yellow seem to do so fairly regularly with not much of a yearly alteration. Red trees on the other hand, seem to make all the difference. What causes trees to turn red at this time of year?
Without getting too technical it is fairly straightforward to explain. For those who like technical, the pigment compounds are termed as follows: anthocyanin for red and purple plant pigmenst; carotenes and xanthophylls for those pigments that are orange and yellow respectively; and chlorophyll for green pigment.
At this time of year green plant pigment is dying off faster than it is begin replaced. Heartier yellow and orange leaf pigments that were masked by the green are now being revealed. The effect is stunning on birch, hickory, maple, witch hazel, willow and many other trees that typically display yellow.
Red pigment, on the other hand, is produced at this time of year. Sugar maple, red maple, sumac, burning bush, red-osier dogwood, red oaks, pin oaks and others typically showcase red. The brightness and amount is dependent upon various environmental factors that change from year to year and one location to another.
As deciduous leaves stop photosynthesis in the fall in response to changing day length, sugars begin to accumulate. These sugars combine with a compound to make this red pigment. Several conditions, when combined together at this time of year can serve to make that pigment bright and showy.
*Acid sap: If the tree is located in acidic soil making its sap on the acid side, bright red leaves result. Alkaline sap tends to mute the pigment into more of a purple color.
*Dry weather: Lack of water getting through to the leaves tends to make the red even redder. Rainy falls find trees still turning red, but not quite as bright.
*Light: Our days are getting shorter at this time of year here in the northern hemisphere, but the earth is getting closer to the sun. Bright sunny days will produce bright red moreso than overcast days.
*Low temperatures: Nighttime temperatures that hover just above freezing kill off that chlorophyll at a faster rate and enhance the formation of the red pigment.
So keep an eye on the weather and the autumn colors and see what correlations you can make.