Category Archives: Mammals

Winning and Losing: Rabbits versus Virus

Invasive rabbit eating invasive rabbit-resistant plant in Australia (photo from Wikimedia Commons)

You would not think that something this cute could be a problem but European rabbits (Oryctolagus cuniculus) have plagued Australia for 160 years. After a century of recurring population explosions (think “plagues of locusts”!) scientists found a virus that kills only European rabbits. They introduced it in 1950 and it worked amazingly well for a while but the rabbit and the virus both evolved. Here’s their story.

Introduced for hunting in Geelong, Australia in 1859, the European rabbit immediately went feral and the population went out of control. Without any predators they covered most of the continent by 1910.

Range of the European rabbit; pink means “Introduced” (map from Wikimedia Commons)

Periodic population explosions, called rabbit plagues, became the norm. The rabbits eat everything. They devastate native plants, push out native animals, denude the countryside and cause dust bowls. In the photo below, at dusk, they are everywhere but probably not a plague yet since there’s still some grass.

So many rabbit holes. No trees or shrubs (photo from Wikimedia Commons)

Hunting and poisoning were ineffective.

Then in 1950 scientists found a virus in South America, called myxoma, that killed European rabbits. They released it in Australia (and in France) and it cut the rabbit population by 99%. Wow!

But a few rabbits lived and so did the virus. Science Magazine reports that “within a decade, rabbit numbers were on the rise again as some evolved resistance to this deadly infection and the virus itself became less deadly.”

This month, a new DNA study of both the rabbit and the virus shows that:

Rabbits on two continents evolved the same genetic changes to beat back the virus—before the virus itself changed and regained the upper hand. […and…] In the 1970s the virus developed a greater ability to suppress the rabbit’s immune responses. That change, as well as the natural emergence of another rabbit-killing virus, has caused populations to decline again.

— Science magazine, 14 February 2019

The arms race continues.

Don’t worry about the rabbits. They had another population explosion in 2004. At last count there are about 200,000,000 of them in Australia.

After all, they breed like rabbits.

For more information, read “Seventy years ago, humans unleashed a killer virus on rabbits. Here’s how they beat it” by Elizabeth Pennisi in Science Magazine.

(photos and range map from Wikimedia Commons. click on the captions to see the originals)

Kits in March

Pair of red foxes, Hain’s Point Golf Course, Washington, DC, Jan 2013 (photo from Wikimedia Commons)

January-to-February is mating time for red foxes in Pennsylvania and the Mid-Atlantic region.

Red foxes pair for life. They remain together from midwinter through summer. In autumn the foxes are solitary but reunite in winter for mating in January or February. Following a period of about 51 days, four to six young are born in late March or early April.

— Guide to the Mammals of Pennsylvania, p. 252 — Joseph F. Merritt

People usually don’t see foxes mating but Carly Lesser & Art Drauglis came upon this pair in January 2013 at Hain’s Point Golf Course in Washington, DC. Click here for another photo and scroll down to read the description.

If foxes mate in January, they have kits in March.

(photo by Carly Lesser & Art Drauglis at Wikimedia Commons; click on the caption to see the original)

Squirrel Appreciation Day


Eastern gray squirrel contemplates another raid on the bird feeders (photo by
Ken Thomas via Wikimedia Commons)

When January 21 is the third Monday of the month, an unofficial celebration falls on Martin Luther King Jr. Day (3rd Monday in January). Today is also Squirrel Appreciation Day (January 21).

Founded in 2001 by North Carolina wildlife rehabilitator Christy McKeown, Squirrel Appreciation Day is a good excuse to learn about squirrels:

How shall we celebrate Squirrel Appreciation Day? This one suggests that we give him a handout.

Grey squirrel, St. James’s Park, London (photo from Wikimedia Commons)

Pittsburgh’s squirrels will be grateful for extra food today. It was 2 degrees F this morning!

(photos from Wikimedia Commons; click on the captions to see the originals)

Truly Sunken Garden Trail

Evidence of beavers: downed trees and orange stump, Moraine State Park (photo by Kate St. John)

Last Saturday I tried to enjoy the Sunken Garden Trail at Moraine State Park but there were challenges along the way. The trail was very soggy, trees were down on the Short Loop, and part of the trail was under a few inches of water.

The flood is the work of beavers who backed up water in the wetlands (above) about 600 feet from the trail entrance (below).

Flooded Sunken Garden Trail, 5 Jan 2019 (photo by Kate St. John)

The Sunken Garden Trail is truly sunken here. Fortunately ankle-high muck boots were more than enough to keep me dry.

Be prepared for mud in this winter’s warm weather. And watch out for black-legged ticks. I got one on my pants after I bushwhacked around downed trees. They’re moving around out there, though in slow motion.

(photos by Kate St. John)

There’s Never Just One Mouse

Emmalina looks at the source of the mousey sound, Nov 2011 (photo by Kate St. John)

On Throw Back Thursday:

Seven years ago when my cat alerted me to a mouse under the heat duct, I knew in my head that there’s never just one mouse.  But my heart refused to listen and I said to myself, “Of course there’s only one mouse, and when I catch that one I’m done.”

Hah!  Every fall I’m reminded that there are victories but in a 111 year old house you’re never done. Thankfully there are so few mice this fall that Emmalina has not noticed them.  Does this mean there are none or that she’s too old to care?

On Throw Back Thursday, here’s how naive I used to be about mice.  It started with Mouse in the House and followed up with The Observer Effect.

p.s. The photo at top is seven years hold. Here’s a recent one of Emmy, 12 years old now, playing with her treat ball.

Emmy plays with her treat ball, Nov 2018 (photo by Kate St. John)

(photos by Kate St. John)

Catnip For Cheetahs

Cheetah at Pittsburgh Zoo, 16 May 2018 (photo by Kate St. John)

When my husband and I visited the Pittsburgh Zoo last spring we stopped by the cheetah exhibit to watch these graceful cats and learn about them from the zoo’s cheetah experts.  We were amazed to find out that cheetahs like perfume. It keeps them from being bored.

Zookeepers have known for years that big cats, including lions and tigers, react to some perfumes the way housecats react to catnip.  They sniff and flemen and rub their faces on the scented spot.  My cat Emmy shows how it’s done with her catnip toy.

Emmy rubbing her face on a catnip toy (photo by Kate St. John)

Instead of catnip the big cats prefer perfume and they don’t like the expensive stuff.   Watch how perfume turns them on in this National Geographic video.

Apparently Calvin Klein’s Obsession for Men is catnip for cheetahs.

(photos by Kate St. John; video by National Geographic on YouTube)

Elk Putting On A Show

Sparring bull elk in Elk County, PA (photo by Paul Staniszewski)

The elk are putting on a show in northcentral Pennsylvania right now and they don’t care if we watch.

Elk or wapiti (Cervus canadensis) are one of the largest members of the deer family.  Males weigh up to half a ton(!) and can be five feet tall at the shoulder with antlers five feet across.  The females, without antlers, are only 3/4 their size. The difference is due to their lifestyle.

From late August through mid-October the elk herd assembles for the mating season, called “the rut.”  The males sound off and fight to win females for their harems.  Bigger is better. The strongest males have the most offspring. 

Their bugling and sparring is fascinating to watch and you can get fairly close because the herd is distracted.  Paul Staniszewski photographed these two locking antlers.

And here’s a 6-minute video shot in Benezette, home of Pennsylvania’s largest elk herd.

Visit Elk County, PA to watch the show. Click here for more information.

p.s. Wapiti were reintroduced in Pennsylvania in 1913 after we extirpated them in the late 1800s. Did you know white-tailed deer were reintroduced to Pennsylvania, too? 

(photos by Paul Staniszewski)

Schenley Park Outing: September 30, 8:30a

Chipmunk (photo by Cris Hamilton)

At the end of September the weather’s fine and there’s plenty to see outdoors.  Goldenrod and asters are blooming but everything else has gone to seed, fruit, and nuts.  This is great news for chipmunks.

Join me for a bird and nature walk in Schenley Park on Sunday, September 30, 8:30a – 10:30a.

Meet at Bartlett Shelter on Bartlett Street near Panther Hollow Road. We’ll see birds, fall flowers, fruits, seeds, acorns and busy chipmunks.

Dress for the weather and wear comfortable walking shoes. Bring binoculars and field guides if you have them.

Before you come, visit my Events page in case of changes or cancellations.

Hope to see you there!

(photo by Cris Hamilton)

Ooops! It Fell

Spray of white oak leaves found on the ground, Sept 2018 (Kate St. John)

In September I often find sprays of oak leaves littering the woodland trails. I used to think they fell in windstorms but I’ve discovered a more common reason. In autumn it’s squirrels at work.

Gray squirrel (photo by Chiswick Chap via Wikimedia Commons)

Gray squirrels build leaf nests high in the trees for shelter in winter, nests for their young, and for sleeping at night.  The outer layer is composed of leaves and twigs that make a water resistant blob about the size of a beach ball. The inside is lined with moss, grass, shredded bark and other soft vegetation. The entrance faces the trunk. 

Squirrel nests can be as much as 70 feet off the ground. Here’s what one looks like. 

Gray squirrel nest (photo by Marcy Cunkelman)
Gray squirrel nest (photo by Marcy Cunkelman)

To gather building materials, the squirrel gnaws near the branch tip — often an oak — until the spray of leaves comes loose.  If he isn’t careful to hold the twig, it falls. Oh well. The squirrel gnaws another one.  

You can tell when a spray of leaves is a squirrel’s handiwork.  The tip of the twig looks chiseled. Teeth made this mark!

Tip of a white oak twig chiseled by a squirrel (photo by Kate St. John)

Last week I found many leafy twigs on the trails in Pittsburgh.  After four days of cold rain the squirrels were making nest repairs.

As winter approaches you’ll find them, too. The squirrels are fortifying their nests and they don’t have much time. The leaves will be gone in November.

(photos by Kate St. John, Marcy Cunkelman and from Wikimedia Commons; caption has a link to the original)