When Do Copperheads Hibernate?

Copperheads are venomous snakes found throughout the eastern and central United States. If you’ve spotted one of these brown, hourglass-patterned snakes near your home, you may be wondering – do copperheads hibernate for the winter? And if so, when do they begin and end their hibernation?

If you’re short on time, here’s a quick answer: Copperheads typically hibernate from late October through mid-April, depending on the local climate and weather conditions.

In this detailed guide, we’ll cover everything you need to know about copperhead hibernation patterns, including what triggers it, how long it lasts, where they hibernate, and how temperature fluctuations impact their activity levels throughout fall and winter.

What Triggers Copperheads to Start Hibernating

Decreasing Day Length

As autumn approaches and the days become shorter, copperheads sense the decreasing daylight which triggers them to start preparing for hibernation. The reduction in day length and sunlight signals to copperheads that colder weather is coming, so they need to find suitable hibernacula sites to see them through the winter months.

Studies show the photoperiod (day length) is key in initiating brumation behaviors in snakes. Once the daylight hours drop below a critical threshold – which varies by latitude and species – physiological and behavioral changes kickstart the hibernation prep process.

The pineal gland in copperheads’ brains detects the shortening days which then triggers hormonal shifts to spur the snakes into action.

Temperature Changes

In addition to decreasing day length, drops in ambient temperature provide another critical seasonal cue for copperheads. As temperatures start dipping in autumn, with more cold snaps and frosts, the snakes sense it is time to retreat underground.

Copperheads typically begin brumation once overnight temperatures regularly plunge below 45-50°F (7-10°C). They can no longer sustain their body heat and metabolism when external temperatures drop so low.

So the onset of sustained cold snaps in fall drives the snakes to seek out suitable hibernacula to see out the winter.

Lack of Prey Availability

The dwindling supply of prey animals in autumn also prompts copperheads to prepare for brumation. Their prey – mice, voles, frogs, toads and other small animals – become scarcer when vegetation dies back and ambient temperatures drop. With limited food supply, copperheads have insufficient energy to remain active so they conserve resources by hibernating underground all winter.

In laboratory experiments with black rat snakes, individuals exposed to warm temperatures but deprived of food still elected to hibernate – demonstrating prey availability is a factor in brumation. This likely holds true for copperheads also.

How Long Do Copperheads Hibernate For?

Hibernation Lasts 5-6 Months

Copperheads typically spend 5 to 6 months in hibernation during the winter. They enter brumation, which is a reptile’s version of mammalian hibernation, in late October or November when temperatures drop.

This allows them to conserve energy and survive the winter when prey is scarce and temperatures are too cold for them to be active.

According to a 2018 study published in Herpetologica, the average brumation period for copperheads is 154 days, which works out to just over 5 months. However, depending on the climate and weather conditions in their locality, this period may be a few weeks shorter or longer.

Emergence Depends on Weather

Copperheads do not hibernate on a strict calendar schedule. Instead, their emergence from brumation depends largely on the weather warming up in their habitat. Typically they will start stirring in late March or April as daytime temperatures reach into the 50s and 60s Fahrenheit more consistently.

However, a cold snap can delay their emergence by a couple weeks.

According to field research by herpetologists, male copperheads often emerge first, followed shortly after by females. The males emerge early likely in hopes of encountering females emerging from other dens. Breeding occurs soon after emergence from brumation.

Where Do Copperheads Hibernate?

Communal Den Sites

Copperheads often gather together in communal den sites to hibernate during the winter months. These communal dens provide additional warmth and protection, allowing the snakes to more easily survive the harsh winter conditions.

Favored denning spots include rocky outcroppings, abandoned animal burrows, hollow logs, and rock crevices. Researchers have documented copperhead den sites containing over a hundred individuals gathered together!According to the South Carolina Department of Natural Resources, the largest winter den of copperheads ever recorded contained 838 individuals.

Underground Burrows

In addition to communal dens, copperheads also frequently use underground burrows and cavities to escape the cold weather. Abandoned rodent burrows are a common choice, as they provide insulation from freezing temperatures.

The snakes may dig further chambers off of the main burrow to give themselves more space. Solitary copperheads unable to find a den mate may opt to brumate alone in a secluded burrow. These single-snake dens can be located under stumps, in abandoned termite nests, or within the root system of fallen trees.

Hollow Logs & Rock Crevices

Hollow logs and rock crevices provide insulating nooks and crannies that copperheads eagerly inhabit during brumation. The small openings allow the snakes to squeeze inside and escape the worst of the cold.

These solitary winter refuges are often hidden under leaf litter or buried by snow, keeping the inhabiting snake safely out of sight. Research by the University of Georgia found that copperheads rely heavily on hollow logs for winter shelter in forested areas of the southern Appalachian Mountains – over 70% of transmitter-implanted copperheads chose logs as hibernacula.

Copperhead Activity During Winter Warm Spells

Brief Periods of Activity

Copperheads typically become inactive during the winter months, holing up in underground dens or rock crevices and entering a state of brumation. However, they may become active for brief periods if temperatures rise above 50 degrees Fahrenheit for a few days.

These winter warm spells can rouse copperheads from brumation and cause them to emerge in search of food and water.

According to herpetologists, copperheads are ectothermic or “cold-blooded.” This means they rely on external heat sources like the sun to warm their bodies. When ambient temperatures climb high enough, their metabolisms speed up and they become more active.

A sunny day in the dead of winter may be just enough to awaken a copperhead from its slumber and stimulate it to move around.

During these temporary warm periods, copperheads typically do not wander far from their dens. They may crawl out to bask in the sunshine or hunt for small prey like mice and insects near their brumation site.

But as soon as the weather cools again, they will return to the safety and insulation of their underground retreats.

Impacts of Climate Change

Some research indicates that climate change may be having an impact on copperhead brumation patterns. Studies have shown the winter activity periods for copperheads are starting earlier and ending later in some regions, likely due to rising temperatures and fewer days below freezing.^[1]

For example, a 2020 study published in the journal Ecosphere examined copperhead brumation in the southern Appalachian Mountains. The researchers found that the snakes were emerging from dens a mean of 8 days earlier and immersing 13 days later over the past 20 years compared to historical data.

They attributed this change to increasing average winter temperatures caused by climate change.

More frequent and prolonged warm spells during winter may allow copperheads greater opportunities to bask, hunt, and replenish their energy stores before the next cold snap. However, emerging too early or late in the season could also expose them to dangerous cold snaps or predation.

It remains to be seen whether these brumation changes give copperheads an advantage or added stress in the long run.

Avoiding Encounters with Hibernating Copperheads

Cautious Yard Work in Fall & Spring

Copperheads typically begin hibernating in late October or November, when temperatures start dropping below 60°F consistently. They will remain dormant throughout the winter months until late March or early April, when temperatures begin rising again.

This means the months of highest risk for encountering copperheads around homes and yards are the fall and spring seasons.

During these transitional months, copperheads may venture out during warm, sunny mid-day temperatures to bask and raise their body temperature. However, the snakes quickly retreat to their underground dens when temperatures drop again in late afternoons and evenings.

Homeowners doing yard work need to be especially vigilant for basking copperheads during the spring and fall.

Here are some tips for cautiously doing yard work when copperheads are most active:

• Wear tall, rubber boots or snake gaiters when working in leaf litter or dense vegetation.
• Use thick, leather gloves when moving logs, boards, or debris piles where snakes may hide.
• Keep grass and undergrowth short to reduce potential hiding spots for snakes.
• Use long-handled tools like rakes, hoes, and pruning shears to avoid putting hands near possible snake hideouts.
• Check any piles before placing hands inside – use tools or gloved hands to shift debris.

Taking precautions like these when doing yard work in the spring and fall can help prevent painful and dangerous copperhead bites.

Watch for Basking in Sunny Areas

Copperheads love basking in sunny spots to raise their body temperature after emerging from hibernation dens. Areas near foundations, steps, sidewalks, and rock walls exposed to sunshine are prime basking habitat for copperheads in early spring.

Homeowners should be vigilant when walking near these places and avoid stepping or reaching into hidden areas before carefully inspecting them first. Wearing closed-toe shoes and long pants provides some protection if accidentally stepping near a hidden snake.

Here are some tips for being watchful of basking copperheads around the yard:

• Inspect sidewalks, steps, and rock walls before using or sitting near them on sunny spring days.
• Keep wood piles, debris, and dense plantings away from foundations and walkways to reduce snake hiding spots.
• Consider keeping pets indoors during the early spring basking hours (typically 10am – 2pm).
• Teach children not to reach under elevated porches, stairs, or into wood piles blindly.
• Use a stick or long tool to shift debris or vegetation before picking items up.

Staying alert and inspecting sunny areas around the home’s perimeter can help avoid surprising hidden copperheads that may be basking in early spring.

Conclusion

In most regions, copperheads begin hibernating in late October and don’t reemerge until mid-April. The exact hibernation timing is influenced by decreased daylight, dropping temperatures, and the unavailability of prey. While in hibernation, copperheads congregate communally in underground dens.

They may briefly become active during unseasonal warm spells. Use caution when working or playing outdoors near potential hibernacula to avoid surprise encounters.