Archive for the 'Mammals' Category

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

Surrounded

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)

Surrounded!

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 audubon.org’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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Jun 26 2015

Not Exactly Squirrel Proof

Published by under Bird Behavior,Mammals

Red-bellied woodpecker and chipmunk at squirrel-proof bird feeder (photo by Jonathan Nadle)

Red-bellied woodpecker and chipmunk dining at a squirrel proof feeder (photo by Jonathan Nadle)

Jonathan Nadle’s neighbor has a squirrel proof bird feeder but it doesn’t keep out all the squirrels.

A small member of the Sciuridae (squirrel) family squeezes though the mesh and helps himself to seeds.

A lot of birds won’t visit while the chipmunk’s there — did you know chipmunks eat bird eggs? — but the red-bellied woodpecker has nothing to fear. His long sharp bill is a formidable weapon.

Red-bellied woodpecker and chipmunk coexist at the squirrel-proof bird feeder (photo by Jonathan Nadle)

(photo by Jonathan Nadle)

“Squirrel proof” might not work for chipmunks but at least it keeps out Pennsylvania’s largest member of the squirrel family –> groundhogs.

 

(photos by Jonathan Nadle)

p.s. Gray squirrels are in the Sciurinae (tree-based) subfamily. Groundhogs and chipmunks are both in the Xerinae (ground-based) subfamily and members of the Marmotini tribe (marmots!).

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Jun 18 2015

TBT: Food For Thought

Gray squirrel (photo by Chuck Tague)

Gray squirrel (photo by Chuck Tague)

Why are songbirds angry at squirrels?

On Throw Back Thursday (TBT), here’s some Food For Thought from June 2008.

 

(photo by Chuck Tague)

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Mar 31 2015

More Deer, Less Moose

Moose and deer (both photos from Wikimedia Commons)

What happens when the interval between spring thaw and leaf out gets longer?  Fifty years of detailed observations in New Hampshire’s Hubbard Brook Experimental Forest tell the tale.

In New Hampshire, where snow covers the ground all winter, spring thaw is a welcome event that finally exposes the soil.  Weeks later after lots of warm air and sunshine the trees leaf out.  In between these two events the sun warms the soil, the plants emerge, and wildflowers bloom.

Hubbard Brook Experimental Forest has kept detailed records of temperature, precipitation, snowpack, plants, animals, birds and invertebrates for more than half a century. An analysis of the data, published in BioScience in 2012, showed that the forest is getting warmer and wetter and the interval between spring thaw and leaf out has increased by 8 days.  Climate change is separating spring’s above ground (air) responses from the soil responses.

In the post-thaw interval severe cold events freeze the exposed soil and kill plant buds and invertebrates. This threatens some deciduous trees (yellow birch and sugar maple in New Hampshire) and birds find fewer invertebrates when they return from migration.  The record shows the mix of plants and animals is changing.

There are even changes in large animals.  For the past 50 years the snowpack has declined, an outcome that favors deer over moose and that seems to be happening at Hubbard Brook.

More deer, less moose.  If you write it down now you can see the trend later.

Read more here in Science Daily, December 2012.

 

p.s. It should be “More Deer, Fewer Moose” but I am quoting one of the articles and happen to like the ungrammatical juxtaposition.

(photo of moose by Ronald L. Bell, USFWS via Wikimedia Commons.  Photo of deer by josephamaker2018 via Wikimedia Commons. Click these links to see the original images.)

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Mar 05 2015

Cover Your Ears

Published by under Mammals

Opossum in winter (photo by Cris Hamilton)

After Tuesday night’s high of 49oF we’re headed for 1oF tonight.  Everything that lives outdoors is in for a huge surprise.  Opossums, in particular, should watch out.

Opossums’ thin ears and naked tails are prone to frostbite.  Though normally nocturnal, they come out during the day when they’re hungry.  That’s how Cris Hamilton photographed this one at her bird feeders in early 2011.

And yes, her backyard possum had a hard winter that year.  His ears are pink because they’re frostbitten.

Opossums! Cover your ears tonight … or stay indoors.

 

(photo by Cris Hamilton)

 

 

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Mar 03 2015

A Mimic On Two Levels

Published by under Mammals

Margay cat or "tree ocelot" (photo from iStockphoto/Jeff Grabert via Science Daily)

One glance tells you this wild cat’s fur mimics his dappled forest habitat.  Amazingly, he can mimic on another level, too.

The margay (Leopardus wiedii) is a nocturnal feline of Central and South America that looks like a small ocelot.  Longer and lighter weight than a pampered house cat, he weighs 5.7-8.8 pounds and is 32-51 inches long (including his long tail!).

The margay lives in trees in the tropical forest and rarely comes to the ground because he doesn’t need to.  He’s so well adapted to climbing that his ankles rotate 180 degrees so he can walk down trees head first.  He can also leap 12 feet straight up to capture small mammals, birds, lizards and tree frogs.

In Brazil one mammal on the margay’s menu is the pied tamarin (Saguinus bicolor), a small primate the size of a squirrel.

Pied tamarin (photo by Whaldener Endo via Wikimedia Commons)

Native Amazonians have long known that the margay can mimic the sound of this monkey, but it wasn’t recently that the rest of the world found out.

In 2005 researchers watched a group of eight pied tamarins feeding high in a ficus tree when a margay, hidden in dense liana vines, tried to lure them by mimicking the call of a tamarin pup. A tamarin “sentinel” climbed down to investigate the noise, then started to warn the rest of the group, but four other tamarins were so confounded by the baby tamarin sound that they too climbed down to see.  At that moment, the margay emerged from the foliage, walking head first down the trunk, and jumped toward the monkeys. Realizing the ruse, the sentinel screamed an alarm and all the tamarins fled. (*)

The Wildlife Conservation Society reported this incident in 2010, the first recorded instance of a wild cat species in the Americas mimicking the calls of its prey.

Pied tamarins are endangered and the margay is “near threatened.”  Large primates (humans) have killed the margay for its fur and the pied tamarin for food.  We’re lucky to have heard of this mimickry trick before it disappeared.

Read more about it here in Science Daily.

 

(Margay photo from iStockphoto/Jeff Grabert via Science Daily. Pied tamarin photo from Wikimedia Commons/Whaldener Endo, Creative Commons license. Click on the images to see their originals.)

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