Archive for the 'Mammals' Category

Feb 28 2014

Raccoon Makes A Mistake

Published by under Birds of Prey,Mammals

 

Late Wednesday night, February 26, at 11:15pm a raccoon climbed the bald eagles’ nesting tree at Hays while a noisy train rumbled by in the valley.  Mother Eagle was asleep but she heard the raccoon’s rustle and stood up to defend her three eggs.  As the mammal crested the nest edge she opened her wings and took a few steps toward it.  The raccoon turned and fled.

When you watch the encounter on this archived video from PixController you can see everything that’s going on, but the participants can’t.  The nest is lit at night by an infrared lamp mounted near the distant camera.  The camera can “see” the infrared light but we, the eagle, and the raccoon cannot.  On that overcast night the animals were dark shapes to each other.  I’m sure the raccoon was frightened to find an eagle!

Raccoons raid songbird nests because the songbirds are powerless to stop them but they avoid raptors because birds of prey will kill them.  Why was this raccoon attracted to a bald eagles’ nest?

Scott Kinsey gave us the hint on PABIRDS yesterday morning when he wrote:

It has been fun watching the Bald Eagle nest cam from Pittsburgh.  Finally got to see a feeding.  I think it was the male brought a fish for the female at 10:39am.  She had it done by about 10:47 and back on the eggs. Might have been a Gizzard Shad around eleven inches?

As Scott points out, the female eagle eats at the nest and though she sets the scraps aside she doesn’t take out the garbage.  Lots of smelly fish scraps are up there on the sticks.   The raccoon probably smelled the leftovers and came exploring for a meal.  When he realized his mistake he was out of there!

This surely isn’t the first time a raccoon has explored an eagles’ nest at night.  We just happened to see it because of the night vision camera.  He was lucky he didn’t make a fatal error.

Click here to see what’s happening right now at the eagles’ nest.

 

(video from the Pittsburgh Eaglecam by PixController)

p.s.  This episode points out another difference between bald eagles and peregrines.  Adult peregrines don’t eat at the nest during incubation and even when feeding nestlings they take out the garbage.

4 responses so far

Dec 30 2013

Prelude To A Fawn

Published by under Mammals

Here’s something you’re unlikely to see in Pennsylvania’s “Big Woods” north of Interstate 80 — a close-up view of a young 8-point buck taunting and sparring with an older one.

You’re unlikely to see this because Pennsylvania’s huge deer herd is quite out of balance up north.  Since doe hunting was suppressed more than 100 years ago the ratio of bucks to does has fallen steadily.  For example, on the first day of hunting season last month a friend saw a herd of 88 deer in Clarion County.  85 were does and the 3 bucks had only spikes for antlers.  To find out how this happened, read Bob Frye’s 2006 book Deer Wars: Science, Tradition, and the Battle over Managing Whitetails in Pennsylvania.

In no-hunt suburban areas, Pennsylvania’s deer proliferate with a good balance of males and females.  They’re used to seeing harmless humans, some of whom offer food, so they don’t mind coming close.

Sharon Leadbitter visits Allegheny Cemetery in the City of Pittsburgh to photograph the large herd.  Last summer she posted a video of a cute fawn frisking among the headstones. This month she filmed these two antlered bucks.

You can tell the young buck wants to spar as he jumps and dances. The older one persistently pushes him away and ultimately wins.

The winner will claim his favorite doe(s) and make more babies.

Their sparring is the prelude to a fawn.

(video by Sharon Leadbitter)

 

2 responses so far

Nov 06 2013

Magic Eyes

Published by under Beyond Bounds,Mammals

When lights shine on an animal’s eyes at night, what color is reflected back at you?

For cats it’s green.  For possums it’s red.  For arctic reindeer it depends on the time of year!

The tapetum lucidum in reindeer’s eyes changes color to cope with the bright light of summer and low light of winter.  In summer their eyes reflect gold, in winter they look blue.

This cool effect was discovered by a team from University College London and University of Tromsø, Norway thanks to funding from BBSRC (Biotechnology and Biological Sciences Research Council).

Watch the video above and read more about the study here at Phys.org.

 

(video from BBSRC via phys.org)

 

p.s. Reindeer have two other amazing traits: (1) They can see ultraviolet light and (2) They have no circadian rhythm.

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Oct 31 2013

Ready For Halloween

Published by under Books & Events,Mammals

Badger (photo from Wikimedia Commons)

The American badger is ready for Halloween.  He always wears a mask.

This nocturnal member of the weasel family isn’t found in Pennsylvania but occurs from western Ohio to the California coast.  He makes a living by digging for small burrowing animals, especially mice, squirrels and prairie dogs so his favorite places are grasslands where the soil is easy to dig and his prey is abundant.  That’s a habitat rarely found in Pennsylvania.

American badgers are nature’s backhoes but they work at night and are usually alone.  This makes them hard to watch and census.  Even so, we can guess they’ve declined or are missing from areas where prairie dogs have been eradicated.

For a 24 minute window on the badger’s life, watch this 1970 video from Mutual of Omaha’s Wild Kingdom which filmed them during the day.  I must say it brought back memories to see Marlin Perkins again.

 

 

(photo from Wikimedia Commons; click on the image to see the original.  Video from Mutual of Omaha’s Wild Kingdom Season 8 Episode 108, Released 01/01/70)

3 responses so far

Oct 30 2013

Hanging On By His Thumbs

Published by under Mammals

Spix's disk-winged bat (photo by Alan Wolf via Creative Commons license)

Here in eastern North America we’re gaining a new appreciation for bats, not just as Halloween symbols but as insectivores, because several of our species are threatened with extinction due to white nose syndrome.  The bats most at risk are those that roost in caves where cool moist temperatures allow the Pseudogymnoascus destructans fungus to grow and infect them.

Spix’s disk-winged bat (Thyroptera tricolor) is far removed from this danger because he lives in the tropics and roosts inside curled leaves.  He recently made news in the journal Nature because scientists discovered he uses the curled leaves as an ear trumpet.

Leaf roosting has made him unusual in other ways, too.  Most bats roost head-down but this species roosts head-up so it can exit the leaves quickly.  Leaves are smooth and slippery so the bat has evolved suction cups on his wings and feet.   These cups look like disks, hence his name.

Above, the bat is showing off his wing disks but his arms look really weird and stubby.  To understand this it helps to know a little about bat-wing anatomy.

Bats’ wings are made of skin stretched from their armpits to their fingertips. Their four fingers, encased in thin skin, have evolved to be very long to give the wings their breadth.  Bats’ thumbs, however, are not inside their wings and their thumbs are short.

Bat wing showing thumb sticking up (from a photo on Wikimedia Commons)

In the photo above you can see the attic bats’ long fingers.  The joint of the wing is at the bat’s hand/wrist.  I’ve circled the tiny thumb. This one has a claw but Spix’s disk-winged bats have a suction-cup there instead.

When bats roost, they close their fingers to fold their wings.  Most bats grab a perch with their feet but Spix’s uses suction cups to latch onto the inside of the leaf.

Suction cups on his feet alone are not enough.  This bat is hanging on by his thumbs.

 

(photo of a Spix’s disk-winged bat taken near Golfo Ducle, Costa Rica by Alan Wolf.  Bat wing from Wikimedia Commons. Click on each photo to see the original.)

p.s. Thanks to Peter Bell for alerting me to this fascinating bat.

One response so far

Oct 16 2013

Deer Among The Dead

Published by under Mammals

 

On Monday I described how American Indians shaped the landscape before European arrival.  We shape it too, though we don’t always realize how.  Case in point: There are more deer in North America now than there were before Columbus landed in 1492.

Because deer are a prey species, their abundance is tied to their predators.  When American Indians ruled the continent they hunted deer for food and to control the population so the animals would not decimate their crops.  They knew that either no deer or too many deer meant less food.

European Americans are still figuring out how to balance the deer population.  We overdid it a century ago by uncontrolled hunting that killed all the deer in Pennsylvania.  Uh oh!  Pennsylvania passed hunting laws and imported deer from Virginia to repopulate our state.

Now we’ve erred on the other side.  We’ve eliminated the deer’s other predators and protected them from hunting so well that their population has exploded into every nook and cranny including city neighborhoods.

Sharon Leadbitter spends a lot of time photographing nature at Allegheny Cemetery in the city’s Lawrenceville district.  Deer are often her photo subjects because they’re everywhere.  In a conversation with the president of the cemetery she learned that about 300 deer live there in three herds.  This is way too many deer for the land to support so they move throughout the neighborhood eating gardens, shrubs, flowers and handouts.

Since most of the “inhabitants” are dead and the living come quietly to pay their respects, the cemetery’s deer are almost tame.  Sharon says this is both a blessing and a curse, “Some of the blessings are that the deer will eat out of your hand if they know you. The curse would be this great interaction. People feed all manner of things to these animals. White bread, cereal, I’ve even seen a candy bar being fed. It only takes once for someone to be bitten or kicked. These are not pets but because the animals have lost most of their healthy fear, people don’t realize that they are still semi-wild.”

Deer browse and gambol among the headstones, unconcerned by living visitors.  Sharon filmed a fawn playing among the tombstones last June while his mother watched.

“The cemetery is a great place to have some quiet time and reconnect with nature,” says Sharon. “Come check it out but always maintain a respectful distance, or even better stay in the car”  when you visit the deer among the dead.

(video by Sharon Leadbitter)

11 responses so far

Oct 09 2013

Cute, Curious, Combative

Published by under Mammals

Red squirrel (photo by Shawn Collins)

So cute!  But watch out, he’s fierce.

His small size, soft red fur, fluffy tail and big eyes are certainly cute but the red squirrel is also curious and combative.  I think his food habits made him that way.

Unlike gray and fox squirrels, red squirrels (Tamiasciurus hudsonicus) don’t bury one nut at a time.  Instead they gather food in a big cache called a midden in a hollow tree or underground.  This takes a lot of time and effort:  climb the trees, walk the branches, bite off the green cones, watch them fall, scurry down later and collect the cones, repeat the process. Along the way they pause to eat at the same prominent locations leaving debris piles, also called middens, that seem to say “I am here!”

The red squirrel defends a 1 – 8 acre territory against everyone, especially other red squirrels.  He’s curious about new arrivals but then, watch out!

First line of defense?  Shout at the competition!  Burst into a sudden loud chatter that slows to a wheezy hiccup.  Really mad?  Jerk your tail and stamp your feet.  Really, really mad?  Chase!

In coniferous forests that’s usually another red squirrel but in mixed forests gray squirrels also get a verbal beating and relentless pursuit.  Though the red squirrels are only 1/2 to 1/3 the size of the grays, the red ones always win.

I, too, have been ejected from a red squirrel’s territory.  He used his voice.  Click here to read about it.

Now that winter is coming the red squirrels are changing into their drabber winter coats and rushing to increase their middens.  They have no patience for anyone.

Cute… ?

Don’t push me!

(photo by Shawn Collins)

5 responses so far

Aug 30 2013

Head-to-Head in Elk County

Published by under Mammals

Bull elk sparring (photo by Paul Staniszewski)

Looking for some excitement?  Want to see large animals go head to head this fall?

This week Paul Staniszewski of Elk County reminded me that the elk rut has begun.  He wrote:

Labor Day usually marks the end of summer. For the Pennsylvania elk herd the shortening length of daylight hours each day triggers an annual event known as the “rut”. The rut usually lasts from late August until mid-October.  … A lot of sparring between bulls takes place that makes for dramatic photographing opportunities.

Male elk bugle and spar to establish dominance in the mating hierarchy.  They’re so preoccupied that Paul has captured some great photos, especially near the Visitor Center on Winslow Hill Rd in Benezette.

Benezette is a 2.65-hour drive from Pittsburgh so you might want to make a weekend of it.  Plan your trip and learn more about the elk here.

(bull elk sparring by Paul Staniszewski)

17 responses so far

Aug 05 2013

Every Dolphin Has A Name

Published by under Mammals

A Bottlenose Dolphin plays in a boat's wake (photo from NASA archive via Wikimedia Commons)

We’re used to the notion that we name dolphins (remember Flipper?) but did you know that dolphins name themselves and call each other by name?

Last month in the Proceedings of the National Academy of Sciences, researchers from the University of St. Andrews in Scotland published a study of bottlenose dolphins (Tursiops truncatus) that explains how dolphins communicate by name.

Using underwater microphones they recorded dolphins’ voices and discovered that each one had his own unique whistle, a signature sound.  Having matched the signatures to individuals they then played back the sounds, one at a time.  The dolphin who “owned” the sound responded.

This is just like what humans do.  If you call out “Kate,” I’ll respond — if I hear you.

Hearing is probably the reason why dolphins have named themselves.  They live in a world where it’s hard to see but easy to hear (sound travels better in water than in air).  They also live in a social group that’s always on the move.  When a friend has swum out of sight they call him and the friend answers.   This makes it easy for the group to stay together.

Researcher Vincent Janik points out that individual communication is also important for mothers and calves. Baby dolphins rely on their mothers’ milk until they are three years old yet they’re just as mobile as their mothers.  What an advantage that they can call each other by name!

Read more about the study and see a video of the research at this link at BBC News.

 

p.s.  This confirms my belief, garnered from T. S. Eliot’s Old Possum’s Book of Practical Cats, that many animals have their own secret names.  We just don’t know what they are.

(photo from Wikimedia Commons. Click on the image to see the original)

One response so far

Jun 25 2013

They’re Off the Clock

Published by under Bird Behavior,Mammals

Svalbard reindeer (photo from Wikimedia Commons)

Last Friday the solstice set our annual biological clocks.  Every day the sun triggers our circadian rhythm. But what if we lived where the sun never sets?  How would we synchronize our daily internal clocks?

In the arctic where day and night last for months a circadian rhythm would be annoying if not a handicap.  Since “day” has no meaning, arctic reindeer solved the problem by turning off their internal 24-hour clocks.

In mammals the circadian rhythm causes melatonin levels to rise at night and fall during the day.  This happens whether or not the sun gives us a cue.

Scientists studying reindeer in Norway (Rangifer tarandus, the same species as caribou) found that they have no rhythmic melatonin cycle.  Instead their melatonin rises or falls abruptly in response to light.  On or off.  No daily clock.

Reindeer need to know the time of year so they can synchronize migration and breeding, but this is easy to do at the equinox when the sun rises and sets.

On Svalbard where this reindeer lives, the sun rose on April 16 and won’t set until August 27.

No wonder he doesn’t care what time it is.  Some days I wish I didn’t care either.

Read more about this study in Science Daily, March 2010.

 

(photo of a Svalbard reindeer, a subspecies of Rangifer tarandus, from Wikimedia Commons. Click on the image to see the original)

One response so far

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