By Plato StefanopoulosThis article is mainly focused on Squamata (lizards, snakes) and only briefly mentions Testudines (turtles, tortoises)
Contrary to popular belief, reptiles don’t hibernate in the winter in milder weather regions. It’s a very common misconception that reptiles completely disappear in fall only to emerge again in spring, while that is not the case at all. In fact, winter can be a somewhat productive time of the year for herping, well, perhaps about as productive as late summer, as seen from my January-to-mid-February 2021 herping exploits. What is important to note about winter herping though is that the outcome of our endeavors is completely at the mercy of the weather.
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| Ocellated skink (Chalcides ocellatus) found in February |
Each reptile, being an animal that cannot generate its own body heat (ectotherm), has a specific minimum and maximum temperature that allows it to remain active, and that varies greatly from species to species (more on that later). In the case of winter, once the temperature gets below that in which local reptiles can be active, they enter what is called brumation. In this state, their metabolism slows down to a minimum, and they sit still at a hidden site that isn’t freezing (hibernaculum), and activity is suspended, until the minimum specific temperature of activity of the reptile arrives. The minimum temperature of each reptile is dependent mostly on two things: the climate they’re mostly adapted to, as well as the animal’s size. For example, Chalcides ocellatus is more heat-loving than Ablepharus kitaibelli and has a higher minimum temperature requirement for surface activity. Also, since Ablepharus kitaibelii is so tiny (less than 2g), it can warm up enough to be active extremely fast even in 8-9 degrees celsius if there are 2-3 hours of good sun, whereas a snake that has a similar minimum temperature but weighs one or two hundred times that weight will take a substantially longer time to reach a decent enough internal temp to be active. Obviously though, there are exceptions to the rule. Snakes and lizards affected by illness will try to bask in temperatures that are too cold, in a desperate attempt to increase their metabolism to fight the disease. Also, tortoises, and weird cold-loving species, for example Natrix natrix and Zamenis situla may become active in the winter in unexpectedly low temperatures without much sun. Freshwater turtles also fall into that category, perhaps to an even more exaggerated degree. They will come out of their underwater hibernacula to become active in days with cold weather. All things considered, reptile activity is so nuanced and unpredictable that we can only say things with so much certainty, however there seems to be a general rule.
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| This adult male balkan green lizard was found basking outside of its refugium on a 18C day with drifting cloud cover in February |
So, the conclusion here is that during winter, we herpers are, as always but to an even higher degree, at the mercy of the weather, waiting for a decent enough warm spell to come by and awaken as many of the reptiles from their slumber as possible for a short amount of time. It is seemingly easier to herp in conditions like these than summer. That’s because of the fact that the windows for activity are small and the weather isn’t that warm. This means that not only do the reptiles come out in numbers and therefore the densities rise, but their behavior and placement each hour of the day becomes more predictable and they are easier to find. For example, they will thermoregulate under shallow cover or by basking in the morning, or will stay like that all day if their internal temperature doesn’t reach levels that allow them to become active, and they may be on the crawl in the noon-afternoon window and then they will gradually retreat again in the late afternoon-evening. These happen in short intervals, so that makes it easier. And on top of all that, since the weather isn’t terribly warm even during the highs of the warm spells, a large proportion of our local reptiles are most often not performing at 100% capacity. Due to them still being relatively cold, so, cool to the touch, they become more slow, and one can get otherwise uncatchable species in hand very easily, like my lifer Dahl’s.
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| Dahl's whip snake young adult found basking outside its refugium on a 21C sunny day of a considerably lengthy warm spell in early January |
Even in the spring season, before road cruising became a thing for me, i would always look for days that reminded me of warm winter days, with temperatures in the high 60s and clouds/dense overcast, which are always useful conditions because they are warm enough to lure reptiles out of their refugia but won’t allow complete thermoregulation and in turn major movement, forcing them to stick close to hiding places and making them more easy to find.
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| Marginated tortoise young adult found foraging at an urban park in the peak of a warm spell in early February |
