Category Archives: Mammals

Cute and Disappearing

Young hedgehog (photo by Reinhold Möller on Wikimedia Commons)

The cutest animal in the UK is disappearing at an alarming rate. The European hedgehog, the adorable star of children’s books, is now vulnerable to extinction in Great Britain.

Since we don’t have hedgehogs in the U.S. you might not realize what a loss this is.

Only half the size of house cats, European hedgehogs (Erinaceus europaeus) have soft spines that are prickly but not dangerous. Unlike porcupine quills the spines have no hooks. Here’s a young one held in the hand.

Juvenile hedgehog (photo from Wikimedia Commons)

Though they are nearsighted, nocturnal and solitary, hedgehogs are blessed with a keen sense of smell that helps them find beetles, slugs, insects and grubs. In summer they are lightweights (1.8 pounds) but in autumn they double their weight to get ready to hibernate.

Hedgehogs are surprisingly athletic. According to Dr. Krista Keller at Univ of Illinois, “They often run several miles a night and are adept climbers and swimmers.” In this way they roam a home territory of 2 to 50 acres.

Hedgehog lapping water in Hyvinkää, Finland (photo by Tero Laakso via Flickr Creative Commons license)

In most of Europe the hedgehog population is stable but by 2007 people began to notice they were disappearing from Britain. A 2018 census found that the population had dropped 66% in just over 20 years. The Guardian reported:

There are perhaps just a million left, representing a 97% fall from the 30 million estimated to have roamed in the 1950s.

No one’s sure why hedgehogs have declined so precipitously but theories include a lack of habitat, a lower insect population, pesticides, road kills, and an increase in predators and competition, especially from badgers.

Climate change is also a factor. Warmer autumns allow baby hedgehogs to be born too late to fatten up for hibernation. This fall more than 500 underweight young hedgehogs were rescued and housed at Tiggywinkles Wildlife Hospital in Buckinghamshire, England. The Suffolk Hedgehog Hospital was so full in October that they ran out of space for new rescues.

Fortunately UK residents are mobilizing to protect and restore hedgehogs to gardens and hedgerows. This video from Amazing Grace: Saving Britain’s Hedgehogs explains how gardeners can help hedgehogs.

With efforts like these, the hedgehog will make a comeback in Britain.

(photos from Wikimedia Commons and Tero Laakso on Flickr Creative Commons license; click on the captions to see the originals)

p.s. Hedgehogs are much easier to find in Scandinavia. This mother and baby were photographed crossing a rural road in Sweden. I saw my “Life Hedgehog” in a friends’ backyard in Finland. So cute!

Mother and baby hedgehog, Avesta Sweden (photo from Wikimedia Commons)

A Massive Rack

Bull Elk near Benezette, PA (photo by Paul Staniszewski)

Though elk (wapiti) resemble white-tailed deer they are much larger and have huge antlers. A bull elk’s rack can reach 3.9 feet across and weigh 40 pounds! That’s twice as wide and five times the weight of the largest antlers on white-tailed deer.

Like all Cervids elk rub their antlers on trees to remove the velvet that coated the bone while it was growing. The velvet had nerves in it so the bull learned the dimensions of his antlers as they grew. When the rack is complete he remembers how big it is. This usually keeps him out of trouble when he rubs on trees or spars with another bull .

This month Paul Staniszewski captured photos of a bull elk rubbing his antlers and grooming in Benezette, PA. It’s amazing how the bull maneuvers in the tight space among the trees. What a massive rack!

  • Antler rub (photo by Paul Stansizewski)

(photos by Paul Staniszewski)

Who’s Outsmarting Who?

Juvenile raccoons contemplating their next move (photo courtesy PBS NATURE)

This morning I went out the back door at 6am — in the dark — with a bag of garbage. I do this every Friday to outsmart the raccoons.

Raccoons are thriving in my neighborhood though we rarely see them. Last night, for the first time in many months, I saw a hunched shadow cross the street on a nocturnal ramble. They’re still here.

Mostly we see their evidence so we try to outsmart them.

The garbage truck arrives in our back alley as early as 6am but we’ve learned from experience that if we put the garbage out the night before the raccoons rip it open and scatter the contents. Nowadays I take out the garbage as close as possible to the garbage truck’s arrival. One morning I missed the truck. Dang!

Seven years ago PBS NATURE premiered a program called Raccoon Nation that showed how creative urban raccoons can be. One of the scientists remarked:

The more obstacles you throw in their way become more challenges, so it’s quite possible that by providing more and more obstacles we are in fact selecting for smarter raccoons.

— from Raccoon Nation program on PBS NATURE

I’ve changed my Friday morning schedule to foil the raccoons. Have I outsmarted them or have they outsmarted me?

Click here for a short web exclusive video of raccoon babies + more exploring in a kitchen.

(photo and video clip from PBS NATURE)

Who Made These Holes?

Empty black walnut shell with holes (photos by Kate St. John)

This nutshell is empty and carved with large holes. Their shape and placement tell us who made them.

In the autumn black walnuts ripen and fall from the trees. They’re covered in yellow-green husks that exude a black stain when you open them.

Black walnut in husk, Schenley Park, 27 Sep 2019 (photo by Kate St. John)

Squirrels don’t care about the stain. They chew off the husk and gnaw the wooden shell.

Fox squirrel making the sawdust fly as he opens a black walnut (photo by Donna Foyle)
Fox squirrel chisels a black walnut (photo by Donna Foyle)

They make four holes, two on each side of the shell. The side that opens quickly is gnawed into one large hole. By their shape you can tell that a squirrel ate the nutmeat.

This fox squirrel gnawed a black walnut in Donna Foyle’s backyard in 2014. Find out how long it took him in How To Open A Black Walnut.

(photos by Kate St. John and Donna Foyle, per the captions)

Very Tame

White-tailed deer are numerous and very tame in Schenley Park. Last week I encountered a doe with twin fawns near the swimming pool.

The family became alert while I was staring at them, but the mother has learned that we humans aren’t dangerous and is teaching it to her kids. How many generations does it take for the herd to become this tame?

Doe in Schenley Park, 29 July 2019 (photo by Kate St. John)
Her twin fawns, 29 July 2019 (photo by Kate St. John)

In the past ten years I’ve seen the landscape change in Schenley Park while the deer population has grown exponentially. Where there used to be thick slopes of false Solomon’s seal and yellow jewelweed there is nothing green now, just carpets of fallen leaves. Having eaten the good stuff they are working on less tasty food, avoiding the poisonous plants such as white snakeroot at their feet in these photos. Some day their range will fail them.

I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.

Aldo Leopold, “Thinking Like A Mountain,” A Sand County Almanac

p.s. Click here for a photo of an 8-point buck I saw in the park yesterday, August 3.

p.p.s. Also see this article: Too Many Deer: A Bigger Threat to Eastern Forests than Climate Change?

(photos by Kate St. John, Schenley Park, 29 July 2019)

Blonde Groundhog

Blonde-colored groundhog near The Waterfront (photo by Bob Holder)

If you bike the Great Allegheny Passage at the eastern end of The Waterfront near Bristol Metals you may see this blonde-colored groundhog. His color has earned him the nickname “Lou.”

Lou isn’t the normal color for a groundhog. They’re usually brown like this one.

Groundhog in a tree at Flag Plaza, 31 May 2014 (photo by Kate St.John)
Groundhog in a tree at Flag Plaza, 31 May 2014 (photo by Kate St.John)

Lou is leucistic, a condition that has a partial loss of pigment in his skin or fur but not in his eyes. Pigment loss in the eyes — making them red (or green or blue) — indicates albinism.

Thanks to Yale Cohen for mentioning Lou and to Bob Holder for the photo.

(photo by Bob Holder)

Deer Damage in The City

Arborvitae showing deer damage, Greenfield neighborhood, Pittsburgh PA, 17 July 2019 (photo by Kate St. John)

Yesterday in Schenley Park when we saw several white-tailed deer quite close to us, I remarked that the deer population is too high for the park.

How can you tell if your neighborhood has too many deer? Take a look at the arborvitae.

Many species of arborvitae (Thuja spp.) are planted as privacy hedges including our native Thuja occidentalis or northern whitecedar.

In the wild and in our yards Thuja trees are a favorite food of white-tailed deer. They browse it from the ground up to the height of their outstretched necks.

When the number of deer is in balance with the landscape, arborvitae have a normal tapered shape. You’d never notice that the deer are eating them.

Normal tapered shape of arborvitae tree (photo from Wikimedia Commons)

When there are more deer than the landscape can handle, their browsing is intense. The trees are cropped close to the trunk — even down to the bark — because the plants can’t replace their branches fast enough.

If your arborvitae trees look like the row shown at top, there are too many deer in your neighborhood, the landscape is out of balance. “Too many” can happen fast. Deer can double their population in just two to three years.

I photographed that row of damaged trees just six blocks from my house. Yes, my city neighborhood has too many deer now. We could protect our trees with netting as described in this video. Or we could give up and never plant arborvitae again.

p.s. There are too many deer everywhere in the eastern U.S., even in the forest. Read more here.

(photo by Kate St. John)

The Measure Of A Mouse

What size of a hole can a mouse get through? If you have ingenuity, time, and tools you can find out.

Matthias Wandel of takes an engineering approach to woodworking. When a mouse got into his woodshed he made a wooden gauge to find the smallest hole the mouse could squeeze through. His seven-minute video, above, became an Internet sensation.

The mouse tried many holes but gave up quickly if they were too small. What limits the mouse from squeezing through? It’s the size of his skull, not the size of his belly that stands in the way.

Near the end of the video a shrew appears. What limits the shrew?

(video by Matthias Wandel of click here for more of his videos)

Easter Lilies Are Poisonous To Cats

Easter lily (photo from Wikimedia Commons)

A flower that’s poisonous to one particular mammal …

If you have a cat, keep this plant far away from him. Easter lilies are extremely poisonous to cats.

Cat montage (image from Wikimedia Commons)

Native to Taiwan and the Ryukyu Islands of Japan, Easter lilies (Lilium longiflorum) are popular flowers at this time of year. Unfortunately every part of the plant is poisonous to cats: the flowers, the leaves, the stem, even the pollen.

Easter lilies are so poisonous to cats that if the pollen touches her and she grooms it away, it will poison her. The result is severe kidney failure.

The poisoning occurs quickly. Signs are evident within 6-12 hours of exposure. There is no antidote but immediate veterinary attention will improve the cat’s chance to live.

The Pet Poison Helpline recommends:

If your cat is seen consuming any part of a lily, bring your cat (and the plant) immediately to a veterinarian for medical care.

Pet Poison Helpline — Lilies Poisonous to cats

Do you have a dog? No worries. Easter lilies are not poisonous to dogs. This message only applies to cats.

Read more about cats at the Pet Poison Helpline. Read about dogs and lilies here.

p.s. Members of the Lilium genus are favorite foods for deer. I have not seen deer eating Easter lilies but I bet they love them.

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

Confuse A Meerkat

Did you know that meerkats have complex alarm calls?

Related to mongooses, meerkats (Suricata suricatta) live in colonies in southern Africa where their biggest enemies are jackals and eagles. Because they’re highly social they warn each other when danger is near. They even have special sounds to describe the source and threat level for each danger — combinations of “danger from the ground” or “danger in the air” with low, medium and high threat levels.

In this BBC Earth video, scientist Marta Manser tests the meerkats under various threat conditions. Everything goes as planned until she tests for “danger from the air!” by presenting them with a taxidermy jackal arriving by balloon.

“The results of that experiment were inconclusive.”

The meerkats looked up, confused. There is no alarm call for “flying jackal.”

(video from BBC Earth on YouTube)