The Northern Pacific Rattlesnake inhabits most of northern and central California where habitat & populations exist, with the intergrade between the Southern Pacific Rattlesnake & Northern Pacific Rattlesnake running along a fairly straight west-to-east line starting around San Luis Obispo county, east to Kern county. That said, the region where the two subspecies cross over may also extend north and south slightly into adjacent counties.
Our (being northern California’s) species of rattlesnake can be found northward into Oregon, Washington, and even in British Columbia. They are active from early to mid-spring (depending on weather conditions), through the summer & into early fall, and hunker down during the cool season at den sites that can house a few to many snakes. They are most commonly found out and about doing snake business during the day when temperatures are between 75 – 85 °F, though when temperatures are hot (around >90 °F), they tend to become nocturnal, as getting caught out in the open during a hot day can prove fatal rather quickly.
Their appearance can vary in color and pattern a bit, but most individuals have dark blotches/spots along back (to view photos, click here). The color of their patterns can vary from very dark, to a noticeable green, yellow and orange tints. Brown, orange, and yellow tints tend to be the most common color hue of individuals and populations seen, with green tints seemingly more common in coastal forest environments. The average size of adult northern Pacific rattlesnakes is roughly 2.5 – 3 feet long, and are the widest species of snake we have in northern California. Their chunky appearance generally stands out compared to other large snake species we have, like the Pacific gopher snake — which can grow longer than our rattlesnakes, but are not as wide-bodied.
Newborn rattlesnakes are indeed born with a single button, though it is essentially silent. Newborns are around 4 – 5″ long, and grow to be about a foot long (give or take a couple inches for some) once they hit a year old. The snakes will continue to grow for several years, with growth stopping or slowing notably between (roughly) 5 – 8 years old.
Rattlesnakes favor rocky terrain, tall grasses/weeds, and areas with solid cover such as wood or other objects they can get under for shelter. In places where their habitat meets up with humans, they tend to spend most of their time in places where similar aforementioned habitat exists for shelter from predators or weather conditions (typically from heat, so cooler places). They are attracted to areas with prey animals, which include smaller rodents such as mice, rats, voles, and gophers, but younger snakes will also prey on lizards, and large rattlesnakes occasionally take on larger mammals such as squirrels or rabbits. Main predators to snakes, rattlesnakes included, are hawks, eagles, owls, skunks, cats, foxes, coyotes, bobcats, mountain lions, and especially humans.
Rattlesnakes, given their name, acquire a new segment (also known as a “button”) to its rattle every time it sheds, which can range from a couple to several segments a year depending on the age, location, and health of the snake. You cannot tell the exact age of a rattlesnake by counting its rattle segments given the variability in shed patterns. Additionally, as they crawl through rocks and other rough debris, sections can break off and lower the total count.
Speaking of age: rattlesnakes can rack up many more years on their lives than most of us think. On average, rattlesnakes tend to live anywhere from 7 – 10 years — however, in places where there’s less human interference, it’s possible healthy snakes can rack up double that. The oldest northern Pacific rattlesnake was a captive named Striker, who was raised by Placer High School for 31 years before being transferred to Sacramento Splash for another 3 years, when he passed away in 2015 at 34 years old due to complications with a tumor.
Rattlesnakes are not the evil beings some believe they are, and they don’t go out seeking humans to attack. It may not seem like it, but snakes are (much) more scared of us humans than we are of them. The only reason they strike is if they fear for their lives, as a last resort. Most bites occur by stepping on a snake when someone is walking or jogging, not watching where their stepping. A good amount of bites also occur when inexperienced people try to catch or kill snakes. Just give a professional a call to come out and remove one if you don’t want it around to avoid any risks you don’t have to take.
Weather and Rattlesnakes
Weather plays a major role in the amount of activity snakes engage in. After all, snakes are cold-blooded, and that goes for all reptiles, meaning the sun and other external sources of heat are what warm up their bodies and allow them to become active (and survive).
Over the last several years, I’ve noticed rattlesnakes are generally most active during the day when temperatures are between 75 and 85. In addition to air temperature, clouds and precipitation are also major factors in snake activity. When rattlesnakes are active through the warm season, we (very) occasionally get some shower or thunderstorm activity. Snakes much enjoy warm season rain, as do most other wildlife species. Notable (if not significant) spikes in snake activity tend to occur after warm season rain, as they take advantage of the somewhat cooler temperatures, increased moisture, and the increase in prey animal activity.
Cloud cover plays a major role in snake activity as well. On a warm or hot day, if cloud cover increases to near 100% coverage, it begins to block out deadly direct sunshine. This amount of cloud cover on a hot day can lift some constraints of hot weather, sometimes allowing snakes to become active at the surface even if air temperatures are rather warm. A sunny 95 degree day is too hot for most snakes, however, a cloudy 95 degree day is much more likely to allow snakes to become active for short periods at a time. Cloud cover on a hot day can prevent the sun from overheating a snake at the surface, as typically, the sun is a dangerous element to a snake during hot weather.
Once temperatures climb into the 90s, they’ll be ducking for cover in the shade as much as they can, and once the 100s arrive, shade is about the only thing on their mind. In the 90s and 100s, snakes will become (more) nocturnal in order to move around and seek prey without overheating, as exposing themselves to the sun on a hot day could kill them if they are caught out in the open with nowhere to hide. When overnight low temperatures stay at or above the upper 60s to around 70, snakes can remain active all night, before retreating to cover as the sun rises again and gives way to another hot day.