Build a Hibernaculum

Photo © Michael Himbeault

Hibernaculum in its Latin roots means, “winter quarter”, with hibernus being Latin for winter. Thus, hibernacula are places of refuge that creatures seek-out in cold climates during winter when resources are limited and temperatures are frigid. As you may have guessed, it shares its origins with the verb hibernate, which describes the behavior of small mammals that spend winter months in small, protective dwellings due to the physiological shifts they experience for cold-weather survival.

hibernating bear

Photo © Jethro Taylor

True hibernation requires an organism to lower its body temperature to near freezing and slow its heart rate from a beat that is in the +100s to a rate as low as four beats per minute. This allows mammalian metabolism to slow down and conserve energy reserves. Small mammals will consume small amounts of stored food during their hibernation while larger mammals, like bears, will abstain from food entirely and live only on their fat reserves.

Common Gardner Snake

Photo © Dave Huth

Scientists banter over the semantics of whether animals such as reptiles, amphibians, and larger mammals technically go into “dormancy,” “brumate,” “experience winter lethargy,” or “hibernate” Most have accepted the general use of the term “hibernate” to describe any changes in behavior, or physiology, made by animals in colder, northern climates during winter months. This often entails burrowing into some structure to conserve energy until food availability and temperatures increase in the spring.

fox den

Photo © Eric Begin

Hibernating animals will use caves, old earthen burrows made by other animals, deep rock crevices, crawl-spaces under houses, attics, tree cavities, fallen logs, and stone walls. The depth and size requirements of the space they overwinter in depends on the organism and whether they are solitary or communal hibernators.


Photo © Eskling

Reptiles and amphibians are ectotherms, which means they are unable to regulate their body temperatures. This makes burrowing into hibernaculum structures an important survival strategy in winter conditions. The availability of sufficient hibernacula is increasingly threatened as land is cleared and converted to urban and suburban developments.


Photo © Erin

A group of researchers in New Jersey tracked threatened Pine snakes’ (Pituophis melanoleucus) use of hibernacula for 26 years to discover patterns in habitationopen_in_new. They found that each year fewer and fewer hibernacula were available for hibernating snakes, mostly due to environmental pressures such as development, habitat loss, and fragmentation. They also found that snakes would regularly return to the same hibernaculum each season, seeking familiar places of refuge. One could speculate that over time, with fewer of these legacy hibernacula, populations of reptiles like these could suffer.


Photo © sprout appreciation

If you are a homeowner in a colder climate, you can support wildlife in your yard by building and maintaining a hibernaculum. These small caves can be used by a variety of small animals seeking shelter to ride-out the winter months; but, may be especially important for snakes and lizards.


Photo © David Kingham

Snakes, lizards, and other reptiles are ecologically important animals that are often misunderstood and underappreciated. Though some homeowners may balk at the idea of using their yards as habitat for snakes, the vast majority of snakes found in northern latitudes are non-venomous and help keep populations of mice and other small mammals in check. Snakes are also an important food source for many beloved birds-of-prey, such as Red-Tailed Hawksopen_in_new.

hibernaculum in progress

Photo © Gareth Christian

Are you convinced? Explore this link to the Toronto Zoo where you’ll find a nice step-by-step guide on building a hibernaculum.

hibernaculum complete

Photo © Gareth Christian

These are a fun and out-of-the-ordinary feature to add to your habitat map. Install one and you may eventually be rewarded with some interesting hibernating visitors on your property. Just remember, it takes wildlife time to discover new habitat and put it to regular use, so don’t be disappointed if your new feature goes unused at first.

Add a hibernaculum to your Map


Photo ©

While logged into your map, click on the Toolshed and choose the third step; adding objects. Scroll all the way over in the objects to find the hibernaculum icon. Select it and add the object to your map.


Photo ©

Make sure to complete the characteristics for this object by telling us whether you monitor your hibernaculum, the type of space that it is, and whether you constructed it or it is naturally occurring.