Butterfly Rites of Spring I: Adult Hibernators

February 15, 2021

By Steve Cary

But first, a big “THANK YOU” to Bryan Reynolds for his fun and informative mid-winter posts. I’m learning a lot from him and hope to team up with him on some future stories as we go along.

Here in New Mexico’s mid-continent, mid-latitude setting, all resident life forms including butterflies have ways to deal with challenging times. Winter, for example, is cold enough (regular sub-freezing temperatures), long enough (few to several months), and predictable enough (annual) to effectively sort adapted from non-adapted creatures. Can’t get through a long, cold winter? Then you don’t live here on a permanent, resident basis.

Read more Butterfly Rites of Spring I: Adult Hibernators

Getting to Hibernation: Best Practices for Living with Bears

A black bear crosses a road near Bandelier National Monument in 2018. (Photo by Jonathan Creel)

By James Robinson
Los Alamos County Councilor

I have been receiving many emails, text messages, and phone calls concerning our increased bear activity, and I thought I would share some best practices to use until winter.

First, some education.

An American black bear this far into the year needs to consume over 10,000 calories a day to build the weight necessary for the winter. Bears are the world’s greatest calorie counters, and easy calories are always the best.

Traditionally, bears would get their calories by eating grasses, berries, acorns, and occasional meat sources. However, when these sources are limited due to drought, bears will often find their way into our roll-carts. These carts are full of better tasting, high calorie food than the bear would find in nature, and we tend to line it up nicely for them on the street — an easy way to make their calorie goal. Like a kid in a cookie jar, once they have positive reinforcement, they will keep coming back for more until the cookie jar is removed or they are punished.

Negative reinforcement of bears can range from yelling and screaming, to electric shocks, rubber bullets, and relocation. Ultimately, the bear might have to be euthanized. All because it kept coming for the cookie in the cookie jar.

This is where we, as residents of this area, come in.

As our area continues to experience extreme drought, we will continue to see more and more bears coming into town looking for food. It is up to each and every one of us to make sure that they cannot find easy food. Only then, can we assure that these bears will not have to face relocation or euthanization.

I have asked the County staff to begin procuring more bear resistant roll-carts. My goal is to get every household a bear resistant roll-cart, however, it will take time to get the carts and deploy them. In the meantime, I am asking all residents of Los Alamos to get creative in keeping bears out of our roll-carts. The easiest solution is to lock the roll-cart in a garage or shed until the morning of your scheduled collection. If you have this ability, PLEASE do this right away.

For those, like myself, who do not have a garage to store our roll-carts, my first recommendation would be to find a way to secure the lid of your roll-cart. This video demonstrates how this can be done using ratchet straps. Another option is to purchase an electric fence (similar to those used for dogs) and build a barrier around your roll-carts. Bears are very pain adverse and often will give up after one shock. Here’s some information from Bear Smart Durango on how to use electric fencing to deter bears.

Other options I have heard is cleaning your roll-cart regularly with ammonia, or even storing dirty diapers in the cart. We are a creative community. I feel we can come up with a million ways to build a better bear resistant roll-cart!

Ultimately, it is up to each and every one of us to protect our bears. I will continue to work on community wide efforts to help our citizens, however, due to the limitations of the Anti-Donation Clause, many of these options are up to the individual household.

As the adage goes, “a fed bear, is a dead bear.” Los Alamos has already seen one bear attack, and a mother bear and cubs relocated. Most likely, these bears will not be the last. By changing our habits, and working a little harder, we can make sure we live in harmony with our bears. It is up to us to take responsibility for the waste we generate.

To learn more about living amongst black bears, be sure to tune in for a talk from Kathleen Ramsay on Tuesday, September 1 at 7 PM. She will discuss the ways that bears access food in our communities, and what we can do to prevent this behavior.

If you have any questions or comments, please feel free to email me at james.robinson@lacnm.us.

If you’d like more information on living with bears, I encourage you to visit this website as well for information on preventing problems.

Super Sleepers

A black bear mother and cub. (Photo by Jon Phillips)

By Daryl Ratajczak, Wildlife Biologist and Wildlife for You Instructor

The start of spring means that New Mexico’s black bears are starting to come out of their dens after hibernating through the winter! Our state’s bears tend to enter their dens between late October and early December. Generally, they emerge from late March to early May. 

Hibernation is a general term used to describe long periods of inactivity sometimes due to extreme cold, but mostly due to lack of food. To put it simply, animals decide to “sleep” through the winter since food resources are scarce or non-existent.

But given the fact that winter — especially in the northern climates — can last months on end, how can an animal survive the entire winter without eating or drinking? That, my friends, is the crux of this amazing adaptation. And bears do it better than any other animal.

Complex Biology Made Simple

Instead of starting off by describing the life processes necessary for an animal to hibernate, let’s start by thinking about your car. Say you were to fill up your gas tank to run a test on fuel efficiency. In other words, what’s the optimum rate an engine needs to operate in order to stay running the longest? 

The answer is pretty straightforward: the slower the engine operates, the longer it will take to burn the gas in the tank. For example, a car driving 70 mph down the highway is going to burn through its tank of gas faster than one idling in the driveway, sitting in the parked position.

Voilà!!! You just learned everything you need to know about hibernation!

Much like a car, animals more-or-less have to put their bodies in “Park” so they can survive the winter on their respective tank of gas (fat reserves). Placing their bodies in “park” and idling through the winter, however, is what is truly interesting and amazing.

Hibernating animals need to drastically reduce the amount of energy (gas) they expend. As most of you know, being active and exercising burns up a lot of energy. So the first thing an animal must do when entering hibernation is to stop moving, hence the “sleeping” part.

Here is the issue … all mammals, even when sleeping, must maintain a constant body temperature and must continue to perform basic life functions. Things like breathing and maintaining a heartbeat to keep their blood pumping are just a few of the more important functions, since they keep them alive. It takes a considerable amount of energy, even when sleeping, to maintain these basic bodily functions. This is what makes a hibernator so special.

Hibernators almost completely shut off their bodily functions:

  • Their respiration rate drops to next to nothing.
  • Their heartbeat is barely detectable at only a beat or two per minute.
  • And their body temperature drops to just above freezing.

In more technological terms, their overall metabolism drops 50 percent for roughly every 20°F they lose in body temperature. This means they’re burning half the energy they would if they were only sleeping. When they go into complete “hibernation mode,” their bodies are literally in a frozen coma. Punxsutawney Phil, the groundhog, is perhaps the most notable hibernator of this sort!

In this nearly-frozen state, they barely expend any energy, but they’re also barely alive. In fact, it takes them quite a bit of time — possibly a day or so — to “wake up”. It’s kinda like trying to start a car that hasn’t been started in a long, long time. It may actually take a while to get it going.

Pretty neat, huh?

And then, there are bears:

A mother black bear in hibernation with her two cubs. (Photo by Daryl Ratajczak)

But wait a minute … aren’t bears hibernators?

Yes and no.

Bears hibernate … but they are not true-hibernators. They are what we call super-hibernators. Or as I like to call them “super sleepers.” Here’s why bears are so extremely special and a phenomenon in the animal world.

When bears hibernate:

  • Their breathing slows to only about a breath per minute.
  • Their heart may beat only about once every 20 seconds.

But this is where it gets interesting …

Their body temperature only drops a smidgen, from roughly 99°F to 92°F. Yet, with only this slight temperature drop, their metabolism has already decreased by 75 percent. They’re literally just sleeping, but barely expending any energy in the process. Because their body temperature is so high and close to normal, they can literally wake up in just a few minutes.

Pregnant females give birth to cubs in the middle of their hibernation, usually from late January to mid-February. The mothers wake up periodically during the rest of hibernation to tend to the cubs, but the newborn cubs stay tucked in close to mom and simply nurse off her the first few months.

Crazy is the fact that although they are sleeping fairly close to how you and I would, they won’t have a need to eat, drink, or poop for up to six months! I could barely make it through the night without doing one of those three! Black bears usually form a fecal plug (kind of like a cork) that keeps them from defecating throughout their slumber.

If humans tried going that long without removing waste, we would die of toxicity from our kidneys not adequately filtering the waste products in our bloodstream.

And craziest of all … bears barely lose any muscle mass, they primarily burn only fat. Bedridden humans, on the other hand, usually lose muscle and bone mass first if they stay in bed too long. Black bears can lose up to 30 percent of their body weight during hibernation!

Now you can see why bears are completely amazing creatures!

Storytelling – A Gift of Winter by Terry Foxx

Terry Foxx storytelling with the help of Eli the eagle.
Storyteller Terry Foxx getting help from Eli the eagle.

Winter! Words and images that come to mind are snow falling, chilly temperatures, crisp air, hugging yourself to keep warm.

Winter is a time of bundling up with mittens, boots, and hats to play in the snow or enjoy the out-of-doors.

Winter is a time of year to snuggle down before a fireplace, drink hot chocolate, read a book, and listen to music.

But winter is also a time of year when young and old used to gather together to tell stories. It was a time when people questioned why the world worked the way it did. The ancient ones told stories to explain the mysteries of life, how fire came to be, how animals survive the cold, and how the world was created. Our electronic world has changed this time of community, of coming together to listen and have fun.

This next Saturday, 11:00 AM, at the Nature Center, storytellers Terry Foxx and Kimberly Gotches will bring back the ancient practice of storytelling during the winter. Using wisdom of the ancients and modern-day science, they will explain how fire came into the world and how animals survive the cold in a fun and interactive program for both children and adults.

So how does science explain how animals survive the winter?

How animals survive has been a curiosity since the beginning and still is one of those marvels of nature that challenges scientists. Scientists are finding more and more about the interesting and complex ways animals survive through periods of cold.

Today we understand there are three basic ways animals survive the winter: migration, adaptation, and hibernation. Although we can categorize three basic forms, the survival of any one animal is sometimes a complicated mixture. Let’s explain a little of the science behind these three survival mechanisms and look at examples.

flight by Terry Foxx

Cranes over Bosque del Apache. Photo by Terry Foxx.


Migration is the movement of animals from one place to another. It can be a short distance to find a warmer niche or long distances to a warmer climate. Migration is stimulated by the changes in day length and temperature.

Some birds fly amazing distances. For example the artic tern nests near the north pole in the summer but in the autumn it flies all the way south to Antarctica, returning north in the spring. That is over 10,000 miles! Amazingly, they find their way to the same place each year. They seem to navigate using the sun moon and stars for direction and have an internal compass for using the Earth’s magnetic field.

A fun place to go in New Mexico is the Bosque del Apache near Socorro. Every year migrating Sandhill Cranes, Snow Geese, and other birds can be seen in the fields and ponds of the Wildlife Refuge. When you get up early in the morning, you can see thousands of birds waking up and flying off to their feeding grounds. It is a breathtaking experience. On their way to and from the Bosque, the Sandhill Cranes fly along the Rio Grande and White Rock Canyon. You can hear them calling as they fly over White Rock.

A fascinating way to record your observations about when birds appear in the spring and leave in the fall is to join the Nature Center’s on-line birders group (www.peecnature.org, press on the header “Learn.” From the pull down menu go Interest Groups and sign-up.). Someone has already heard cranes heading north—and it is February (we still think it is winter)! Other birds are of particular interest in their coming and going. Nature Center birders anxiously await the first hummingbird signaling summer.

When we think of migration we often think of birds, but other animals also migrate, sometimes not long distances. For example an earthworm can move farther down into the soil below the frost line to survive freezing. They have been found six feet beneath the soil surface (for an earthworm that probably is a really long way!). When the soil warms, they move back up toward the surface.

Insects also migrate. Most well-known is the migration of the Monarch Butterfly. Butterflies can migrate 2500 miles! Those butterflies that live in the East migrate to Mexico and hibernate in oxyamel fir trees. If the butterfly lives west of the Rockies, it heads for Southern California. Monarch butterflies are very important pollinators and are disappearing because of urbanization and agricultural practices. A fun citizen science project is to track the path of the Monarchs.

The Nature Center has an interest group called “Butterfly Watchers.” Sign up on the website www.peecnature.org and follow the directions above. You will learn about different butterflies and you can report when you see a Monarch.

Abert's squirrel with winter ear tassels. Photo by Beth Cortwright
Abert’s squirrel with winter ear tassels. Photo by Beth Cortright.


Adaptation is another way animals survive the winter. To keep warm some animals grow a thicker coat of fur. Examples include coyote, big horn sheep and deer. In some animals, the hairs are hollow, making them more insulating.

As a protective mechanism from predators, the new fur may be white to hide them in the snow. Examples are the Snowshoe Rabbit and Arctic Fox. Other animals gather extra food in the fall and store it. Animals like the fox may eat berries in the summer and small mammals in the winter, changing their food source. Rabbits and deer spend winter looking for moss, twigs, bark. and leaves to eat.

A variety of animals find winter shelter in holes in trees or logs, under rocks or leaves, or underground. These shelters are warmer and animals like mice, raccoons, and squirrels huddle together to stay warm.

Black bear in hibernation.
Sleeping black bear.


Hibernation is a complex and fascinating process. Heart rates drop sometimes as low as 4 four beats per minute and respiration drops to one breath every three to four minutes! Scientists distinguish between true hibernators and those who use torpidity as a mechanism. Regardless, many animals sleep for extended periods of time and spend a lot of time in the late summer and autumn finding food to increase their fat stores within their bodies. True hibernators don’t wake up until spring regardless of the stimuli. Examples of hibernators are chipmunks, ground squirrels, bats, and some mice. They have enough fat reserves to carry them through the winter.

Animals like raccoons and tree squirrels use torpidity to help them survive. Torpidity is a reduction of the metabolism which allows for lower body temperature and oxygen consumption. This is a special, very deep sleep. The animal’s body temperature drops, and its heartbeat and breathing slow down. It uses very little energy. These animals can sleep for weeks at a time and then wake up to eat and defecate. During their wake time they seek out their hidden caches of food collected during the summer and fall.

So what about bears? Are they true hibernators or not? Scientist disagree with terminology. But one thing is for sure, don’t disturb a bear in his sleepy state because he can wake up in an instant, attack, and then go right back to sleep!

We have mostly talked about warm-blooded animals, but cold-blooded animals such as frogs, snakes, and lizards must also survive through winter. They lack internal control over their metabolism. They depend on the warmth of the sun to keep them active. In the winter they would freeze if they did not seek shelter and undergo chemical changes to prevent freezing. They can burrow into the mud or congregate in small caves. Rattlesnakes, for example, congregate in rock crevices to hibernate for the winter. Those spots are known as “snake dens” and they are used every year.

If you want to learn more about how animals survive the winter, here are some books you can find in Mesa Public Library. Some are entertaining stories and others are informative non-fiction.

Hibernation by Anita Ganeri

The Mitten by Jan Brett

Bear Snores On by Karma Wilson

Time to Sleep by Denise Fleming

Animals Hibernating by Pamela Hickman

Do Not Disturb: The Mysteries of Animal Hibernation and Sleep by Margery Facklam