Last update: 02/12/2008

Thanks to Christophe Simoncelli for their photos.

Hibernation (winter sleep) : is the state of dormancy in which some animals spend the winter in colder latitudes.  (typically October through April in the Northern Hemisphere).

The estivation
(Summer sleep ) : an other state of dormancy in which like other species snails spend periods of heat or drought in warmer latitudes.


1 - estivation:

The snail lives short periods of great activity, which are essential for building up its reserves. These allow him a  slowed down long term life.
Mais l'activité provoque l'usure et le vieillissement tandis que la vie ralentie apporte un repos réparateur. Activity causes wear and aging while slowed  life brings a refreshing rest.
The snail's rest periods frequent and regular assure a relatively long life.
The snail sleeps in summer during digesting, or pending the favourable weather to eat.

Drought and heat cause sleep therefore long-term (no feeding), while the daily sleep is the need for rest successive after a great activity.

2 - The hibernation: adapt or ..... Perish!

Winter is a long rest period, the prolonged fasting. Snails must deal this with a maximum of reserve because it can take rest 4 to 6 months.  They will come into hibernation when the temperature falls under 12 at 15 ° C.

In many ectotherm animals , ie unable to regulate their temperature, winter also corresponds to an entry in life slowed. From October to March, helix aspersa seal its shell by an operculum (épiphragm) and stops feeding. His oxygen consumption decrease from 0035 cm3/g/h in activity to 0,014 cm3/g/h during hibernation. This decline in consumption is explained not only by the immobility of the animal, since at rest, during the summer, it is 0026 cm3/g/h. The reason is a slowdown of the vital functions : the heartbeat spend from 100 per minute at 38 ° C, to 1 per minute below 0 ° C. The metabolism, among ectotherm as escargot, depends on temperature : a minimum temperature is crucial for the functioning of enzymes necessary for any biochemical reaction. Many ectothermes (lombric, frog, snake ,...), therefore burrow in the ground or in a cavity, numb with cold, and can become active in a timely warming. petit gris epiphragme

Herewith, a defense thesis: Hibernation and cold resistance at the snail squirrel Helix aspersa Müller (Gastéropode, Pulmoné)
By Armelle ANSART

In Britain, terrestrial snail Helix aspersa Müller (Gastéropod, Pulmoné) enters into hibernation around October, under the combined action of  the decreasing day length  (from 16 to 12 hr depresses significantly mean supercooling points (SCP) and water content of Helix aspersa Müller ) and low temperatures. With a limited capacity of cooling and survival limited to the freezing of is tissues, H. Aspersa can be seen as an animal "partially freezing tolerance."  During the winter, its survival at temperatures negative is improved mainly by the occupation of boxes of hibernation and the moderate expansion of its capacity for cooling. It is caused by a set of characteristics specific of the animal and  the process of achieving dormant : the decline of the water causes the concentration of solutes and less likely nucleation, the formation of an epiphragm , coupled with the presence of the shell, is a barrier against freezing, fasting due to the cessation of the activity involves the evacuation of nucleants agents in the digestive tract. Meanwhile, the relatively large size of this species, its particular shape and the presence of the shell, it has a certain ability to withstand the freezing of tissues. If this capability does not seem to have adaptive value in the learning environment, where temperatures rarely descend below the crystallization temperature of snails, it could prove essential for animals subjected to a cold environment. The interim status of H. Aspersa in terms of strategy hardiness, as compared to the conventional models of insects and vertebrates, is discussed, in view of its implications in the evolution of land snails into circles to colder climate.

Jury compoed of de :
M. Jacques Daguzan, Université de Rennes 1
Mme Maria Lazaridou-Dimitriadou, Université de Thessalonique (Grèce)
M. Martin Holmstrup, National Environmental Research Institute (Danemark)
M. Philippe Vernon, Université de Rennes 1
M. Michel Matthieu, Université de Caen
M. Alain Canard, Université de Rennes 1

3 - The Pomatia case:

pomatia hibernation To protect him of the winter,  Burgundy hollow a small cavity in the ground, turns and hidden a large limestone cap called "seal." For more than a century, we are trying, but we do not know operculer artificially Burgundy snail.

According to some books, essays hibernation "deprivation" have been realized; lines have become sterile beyond 2 generations.

4 - Drying:

Before making snails hibernate, it is necessary drying they.

This stage will last for one week during which the snails bailed their intestine and make the emptiness of their water.
They can be dried either in a box, or on pallets:

Drying snails in a box fitted with a fan to promote ventilation.

Snail drying on pallets, wrapped in potatoes bags.
If you do not have a lot of snails, you can dry them in a wooden box.
Close-up of a snail épiphragme eventually drying. On the left is ok, right, it's not good.

In the 2 following photos, early formation of the epiphragm (left photo). He  is transparent.
Right, épiphragme well trained. The latter is completely opaque.

début de formation de l'épiphragme Gros plan de l'épiphragme
Start Development of epiphragm. Epiphragm full developed.

Focus on the formation of the snail epiphragm before hibernation.
La formation de l'epiphragme

When the drying period is over, snails should be put into hibernation (cold room).

5 - The hibernation:

When the number of snails is limited, the purchase of a cold room is not profitable. I will therefore introduce other 2  cheaply methods for hibernation : the refrigerator and leaves.

The refrigerator:

The refrigerator can easily replace the cold room. Il suffit de mettre les sacs sur les étagères et de surveiller la température qui doit être de 6° environ. Simply put bags on the shelves and monitor (the temperature should be around 6 °). The disadvantage of this method is the need to monopolize a fridge only for snails. Indeed, the smell of dead snail is particularly important, so if you do not want to hear your wife screaming or playing  with the rolling pin ...........

You may use the thermometer mini-maxi to allow the well temperature.


This method will be able to use the ower of "insulation" from dried leaves.

In a escargotière, put a plastic sheet on the ground to avoid rising damp in the event of significant rainfall.
Put a wooden pallet on which to base bags snails.

If you have only one specie of snail, it 's not necessary  install a palett, but a layer of dead leaves on which rest your snails.
Put  bags on the pallet, and cover it with a good layer (20 or 30 cm) of dried and crushed leaves.

The indispensable tool remains is the thermometer mini-maxi to be installed at the snails level. He is the one who will tell you the temperature gain of your "isolation" compared to the outside temperature.  Normally, you can earn 10 ° C without any problem, it depends on the region and orientation. One of my escargotière is oriented south, it is preferred for hibernation.
On the pile of leaves, install a layer or two of P17.  It is a veil for wintering plants susceptible to cold, for sale everywhere.
On the backbone of the escargotière, put a plank of wood to protect against a net overweight due to snow, cats, etc. ....

Then a plastic tarpaulin to protect it from rain.
The most important thing is to avoid moisture!.     

It is necessary to monitor weather bulletins. The "peaks" at -15 ° C are not a danger (it took several hours before reaching snails).
If the weather announcement is -15 or -20 ° C for a while, and your gain is 10 ° C, it will take the necessary precautions if you do not want that your snails crystallize: P17 additional layers, blankets , etc. .....

If the cold became intense, put them in the garage waiting to milder climes (have put snails in bags is a good idea !!!).
Likewise for the temperature too high. It's not very serious if the temperature sometimes reaches 15 ° C during the day. They are not going to wake up to that.

As for the system of the fridge, remember to remove the deads to avoid contaminating the whole batch.

Personnely, I use the 2 methods. That way, if an accident occurs (flood, power outage, fridge down, Siberian cold, ...), and you limit the losses.

In early spring, if you have not put your snails in bags, you should see them rise to the surface.  It was the right time to wake them up. Otherwise, it's up to you to get out of the bags.

6 - Losses:

Remind yourself that hibernation is a natural selection, and the snails weak and sick will not survive! And it is NORMAL !!!!!
It is important to pass these 2 steps (drying and hibernation) in order to limit losses. In fact, a revival of snails in the winter and then a return to cold is fatal. I lost 5000 last year.

Les juvéniles dont le grand diamètre de la coquille ne dépasse pas 19 mm restent potentiellement actifs pendant la phase hivernale et subissent une mortalité importante en période de froid. Juveniles whose large diameter of the shell does not exceed 19 mm still potentially active phase during the winter and undergo a significant mortality during cold.

By the Numbers: a mortality rate of 10-15% of adults seems normal, more for the funds of park (50-80%).
To reduce the losses of "non-lined" (fund park), the smallest (less than 1 cm) can stay in the garage in a box of hibernation, or in mini-greenhouses. They will join the fleet in feedlots in the spring, when frosts are no longer feared.