Archive for the 'Mammals' Category

Nov 04 2015

Teens Drink More In Crowds

Published by under Mammals

The mouse who gets (roaring) drunk C57BL/6 (image from The Jackson Laboratory linked from

Duh!  “Teens drink more in crowds” is not earth-shattering news.  The news is that these teenage mice drink more in crowds, too.

The discovery was made while looking for something else.

In 2013 psychologists Laurence Steinberg and Jason Chein of Temple University asked the question, “Does verbal peer pressure make teens drink more, or is it actions and not words that prompt them to do it?”  Since it’s impossible to run a controlled non-verbal test on drinking humans, they looked for a critter that voluntarily drinks alcohol.

Enter Mouse C57BL/6, otherwise known as Black-6, the most studied mouse on earth.  He’s an inbred lab mouse known for obesity, alcohol consumption, morphine addiction, a weakened immune system, pain sensitivity, atherosclerosis and age-related hearing loss.  And he can’t use verbal peer pressure. “We chose mice for this experiment, said Steinberg, “because mice don’t know what their friends want them to do.”

Science Daily explains what happened,

For the study, a sample of mice were raised in same-sex triads and were tested for alcohol consumption either as juveniles or as adults, with half in each age group tested alone and half tested with their agemates. The researchers found that the presence of “peers” increased alcohol consumption only among adolescent mice.

They published their findings two years ago in Developmental Science as: Adolescent mice, unlike adults, consume more alcohol in the presence of peers than alone.  I learned about it when I read Elizabeth Kolbert’s August article in The New Yorker:  The Terrible Teens.

The mice had a good time and no one got hurt.  Fortunately mice can’t drink and drive.


(photo linked from the article From Mice To Men at, where it was posted courtesy of The Jackson Laboratory. Click on the image to see the original article at Science Node)

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Oct 23 2015

Here Today, Asleep Tomorrow

Published by under Mammals

A chipmunk looks out from his burrow (photo by Chuck Tague)

A chipmunk looks out from his burrow (photo by Chuck Tague)

Every autumn I miss the moment when the chipmunks disappear.

For weeks they’re vocal and active while they gather food to store in their underground burrows for the winter.  Then one day they stay underground and go to sleep.  Days or weeks later it dawns on me, “I haven’t seen a chipmunk in a while.”

Chipmunks (Tamias (Tamias) striatus) are not true hibernators. Instead they go into periodic bouts of torpor in which they lower their body temperature and sleep deeply, then wake up to eat and defecate. On warm winter days we see them out foraging.

Ironically an unusually warm winter is fatal to chipmunks.  A study by Craig Frank at Fordham University found that chipmunks are less likely to enter torpor when the weather’s warm.  Those who do enter torpor have an 90% winter survival rate.  If they stay awake in warm weather, they die.  (90% mortality. Yow! Climate change is bad for chipmunks. Click here to read more.)

Some day soon the chipmunks will go underground, enter torpor, and not resurface until a warm winter day.  Will we notice their absence?

Here today, asleep tomorrow.


(photo by Chuck Tague)

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Oct 06 2015

Food For The Extinct

The "monkey ball" fruit of the Osage Orange tree (photo from Architect of the Capitol via Wikimedia Commons)

The “monkey ball” fruit of the Osage Orange tree (photo from Architect of the Capitol via Wikimedia Commons)

Why is the Osage orange (Maclura pomifera) “monkey ball” such a prolific fruit when almost nothing eats it?

Why is the avocado seed so large?  (Persea americana)

Open avocado showing huge seed (photo from Wikimedia Commons)

Open avocado showing huge seed (photo from Wikimedia Commons)


Why does the honey locust (Gleditsia triacanthos) have huge thorns on its trunk?  And…

Honeylocust thorns (photo from Wikimedia Commons)

Honeylocust thorns (photo from Wikimedia Commons)

… large seed pods that no one eats?

Honey locust seed pod (photo from Wikimedia Commons)

Honey locust seed pod (photo by Andrew Dunn from Wikimedia Commons)

These fruits are food for giants that are now extinct.

Just 13,000 years ago the Americas were inhabited by mammoths, horses and giant ground sloths whose diet included “monkey balls,” avocados and honey locust pods.  Only a giant could eat such large fruit in one gulp and pass the seeds through its digestive track.

The giant ground sloth (Megatherium) for instance weighed 4 tons (8,000 pounds) and could reach 20 feet up when he put his paw on a tree trunk and stood on his hind legs.  He could also damage the trees so the honey locust evolved big thorns for protection.

Megatherium, extinct ground sloth (illustration from Wikimedia Commons)

Megatherium, extinct ground sloth (illustration from Wikimedia Commons)

He’s been extinct for 10,000 years, but the tree remembers.


For a fun 5-minute video about the fruits that point to missing mammals, watch below.



(photos from Wikimedia Commons. Click on each image to see its original)

Notes and links:

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Sep 23 2015

Tock Tock Tock

Published by under Mammals

Here’s a hollow sound you often hear in the woods but you rarely see who’s making it.

Tock Tock Tock Tock, the sound travels and is echoed by additional singers.  Who’s making this sound and what does it mean?

The knocking is a chipmunk warning call that means “Danger From The Air!”  One chipmunk has seen an aerial predator and has frozen in position to warn everyone they’d better watch out.  The other chipmunks freeze, too, and echo the call until it’s impossible to tell where the warning began.

The video below shows the sound as we usually encounter it — a disembodied knocking.  In this case it’s louder than thunder.


If I’d known the sound’s meaning I would have looked for a raptor during my walk in the woods.


(videos by Mark Czerniec and MyBackyardBirding on YouTube)

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Sep 16 2015

Which Weasel?

Published by under Mammals,Travel

A stoat or short-tailed weasel, Mustela erminea (photo from Wikimedia Commons)

Short-tailed weasel, Mustela erminea (photo from Wikimedia Commons)

“Best Mammal” on my trip to Maine was an animal with three or four names but I don’t know which ones until I identify him — and that’s mighty hard to do, even for professionals.

While puttering around the South Lubec sand flats looking for shorebirds, I noticed animal prints in the damp sand.  They were almost the size of cat prints but the toes showed claws and the prints weren’t using direct register (hind prints stepping into front prints).  They looked sort of like this:

I guessed weasel but not necessarily the short-tailed weasel illustrated here. It may have been a long-tailed weasel.  (Click here to see his prints.)

On my way out I saw a weasel cross the dirt track ahead of me and disappear into tall weeds.  He was a long russet-colored mammal about the size of a red squirrel with short round ears, stubby legs, and a long black-tipped tail. His tail was at least as long as his body.

“Size of red squirrel” says short-tailed weasel.  “Long-as-body tail” says long-tailed weasel, shown below(*).

Long-tailed weasel (photo from Wikimedia Commons)

Long-tailed weasel, Mustela frenata (photo from Wikimedia Commons)

With such a short glimpse I can identify him generally but not specifically. His genus is weasel (Mustela), his species is either short-tailed (Mustela erminea) or long-tailed (Mustela frenata).  The two are notoriously hard to tell apart.  I’ll never know for sure.

No matter what he is he will soon shed his brown fur and turn white to match the winter landscape. If he’s a short-tailed weasel (erminea) you’ll recognize him as the ermine or stoat that’s native to Eurasia and North America.  His long-tailed North American cousin is just larger.

I’d like to see this weasel in his winter clothes but I’m not going to Maine in winter to find him. 😉


(photos from Wikimedia Commons. Weasel tracks linked from U.S. Forest Service Pacific Southwest Research Station.  Click on the image to see the original)

(* I didn’t take his picture — these photos are from Wikimedia Commons — so I had to rely on my memory.  Luckily least weasels don’t live in Maine so that narrows it to 2 possibilities.)

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Aug 25 2015

How Fast Do Antlers Grow?

Published by under Mammals

Bull elk with large velvet antlers, late July (photo by Paul Staniszewski)

Bull elk with large antlers in velvet, 22 July 2015 (photo by Paul Staniszewski)

When you see elk antlers and realize they’re shed and regrown every year, it makes you wonder, “How fast do these antlers grow?”

Antlers are a key component of the elk’s (Cervus canadensis) reproductive cycle.  Only males have them and they use them to fight over mating rights.  Sometimes a bull’s body and antler size are enough to intimidate a smaller male but if no one backs down they fight head to head — and can be seriously injured in the contest.

Bulls shed their antlers in early winter so every male starts with a bare head in the spring and grows a complete set by mid August when the rut begins.

Here’s a typical bull on May 30 with short antlers in thick velvet, photographed by Paul Staniszewski in Elk County, Pennsylvania.  The velvet is a soft layer of highly vascularised skin that protects the growing bone.

Bull elk with velvet antlers, 30 May (photo by Paul Staniszewski)

Bull elk with growing antlers, 30 May 2015 (photo by Paul Staniszewski)

Only 53 days later, on July 22, the antlers are still in velvet but nearly done growing as shown at the top of this article.

Just before the rut begins the antlers stop growing and the males rub off the velvet against shrubs and trees to shed the dead skin.  Below, a bull has shed all his velvet except for a bit hanging from the tip.

Velvet is nearly gone, 22 August 2015 (photo by Paul Staniszewski)

His antler velvet is nearly gone as this bull elk reaches to eat a pear, 22 August 2015 (photo by Paul Staniszewski)

When complete the rack weighs 25 to 40 pounds and can be 3.9 feet long with a span 5 feet wide.  To reach this size the bone grows nearly an inch a day!

And now, in mid-August, the rut begins.

Bull elk sparring (photo by Paul Staniszewski)

Two bull elk sparring (photo by Paul Staniszewski)

If you’d like to see elk sparring visit Elk County, PA from mid-August to October.  Learn more here at the Elk Country Visitors’ Center website.


(photos by Paul Staniszewski)

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Aug 14 2015


Published by under Mammals

Elk bellowing, Benezette, PA (photo by Paul Staniszewski)

Bull elk at Benezette, PA, 3 August 2015 (photo by Paul Staniszewski)

When photographer Paul Staniszewski saw this bull elk resting in a field in Benezette, he set down his camera bag and moved in for a closer shot.

Soon he heard a sound behind him.

Another bull was checking out his camera bag.

Radio-tagged elk, 2D, inspects Paul Staniszewski's camera bag (photo by Paul Staniszewski)

Radio-tagged elk, 2D, sniffs Paul Staniszewski’s camera bag (photo by Paul Staniszewski)


These 600 to 1,000 pound animals are dangerous when irritated.  Fortunately Paul is very familiar with Pennsylvania’s elk and knows their moods.  He waited quietly to retrieve his bag.

In early August the bulls are curious but their attitudes will change in a matter of weeks.  When the rut (mating season) begins they’ll be irritable and aggressive, sparring for dominance and mating rights.

September and October are a good time to see their power on display as the bulls battle with their impressive antlers.  Just don’t get surrounded.


(photos by Paul Staniszewski)

p.s. The Pennsylvania Game Commission has placed radio tags on some of the elk to track their movements.  “2D” is one of them.

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Jul 23 2015

TBT: City Raccoons

Published by under Mammals

Raccoon family (photo by Chuck Tague)

Raccoon family (photo by Chuck Tague)

On Throw Back Thursday (TBT), a look back to the time when there were fewer raccoons in my neighborhood:  City Raccoons in July 2008.


(photo by Chuck Tague)

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Jul 08 2015

Too Many Ticks? Hire a Possum

Virginia opossum (photo by Drcyrus from Wikimedia Commons)

Pennsylvania won an award again though there’s no reason for applause.  For the third straight year we lead the nation in reported cases of Lyme disease.

One could argue that we won because Pennsylvania is a big state with a large population, but we also have too many black-legged ticks, too many tick hosts that carry Lyme disease (mice), and too many deer carrying ticks long distances to other locations.  Black-legged ticks are now present in every county in the state.

What to do?  In April I wrote about the many effective ways to reduce ticks around your house and protect yourself outdoors.  But here’s an unconventional solution.  Get yourself a ‘possum.

Like all mammals, Virginia opossums pick up ticks in their travels but the good news is that they don’t carry Lyme disease and they groom so meticulously that ticks don’t stay on them for long.  In fact, when a possum finds a tick on its body, it eats it!

Weird as they are, possums have some advantages.  They consume up to 5,000 ticks in one season and are practically immune to rabies and venomous snakes.

So as we do our best to combat Lyme disease — especially in May through July when black-legged ticks are so hard to see in their tiny nymphal stage — remember that having a possum in your yard is a good thing.

Too many ticks? Hire a ‘possum!


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

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Jul 01 2015

Mr. Mouse Went A-Courting

Published by under Mammals

House mouse (photo via Wikimedia Commons)

House mouse (photo from Wikimedia Commons)

Did you know that male mice sing to attract the ladies?

We can’t hear their songs because they’re way too high for our audio range but each species has its own song and they vary the tunes to fit the social setting.

I learned about this in April’s Audubon news when they highlighted Duke University’s research into mouse songs.  The article included this video of two mouse songs with the audio track digitally lowered so we can hear it.

First a researcher places fresh female urine in the male’s enclosure. Mr. Mouse can smell her but can’t see her so he sings a loud and complex song.  Next they put a female in the male’s enclosure.  When he finds her (why does it take so long?) he snuggles up and sings a softer, simpler song.

What do the lady mice think?  When placed alone in an enclosure with a speaker playing male songs, most females stay close to the speaker when the complex songs play.  Perhaps those songs say “Come hither!”

Click here to read more in Audubon Magazine.


p.s. We can’t hear mice sing at 50 kHz, but cats can. 😉

(video from’s Vimeo site. photo of a house mouse from Wikimedia Commons; click on the image to see the original.)

The title is a reference to “Frog Went A-Courting” in which Frog sings to woo Miss Mouse.

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