Side-blotched Lizard

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.


Okay, changing things up a bit. I had planned on presenting a different species; however, I came across this guy at the beginning of the week and thought he’d help the sequence flow along a little better. This is Uta stansburiana, the Side-blotched lizard, a species that at first glance can look somewhat similar to the Western fence lizard we just looked at. Like the Western Fence lizard, the Side-blotched lizard is a small, fast, diurnal (active during the daytime) species of lizard that feeds primary on insects. Hmmm, why is it called a Side-blotched lizard?

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Boom! Regardless of dorsal pattern and coloration, Side-blotched lizards will display an axillary (near the arm pit) dark patch, as seen here. They are present bilaterally (on both sides) and both sexes have them. In addition to these blotches, which Fence lizards do not have, the Side-blotched lizard has fine, granular scales, as opposed to the spiky, coarse scales of the Fence lizard.
In most instances one cannot get very close to these flighty little lizards. This individual, however, was a very bold male that stood his ground when I approached. His machismo allowed me to show you another key difference between the two species…..

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Have a look at the obvious differences on the ventrum between the male Side-blotched lizard (left) and the male fence lizard. Again, the hemipenal buldges and large femoral pores are indications that this Side-blotched is a male (in addition to his territorial behavior). Take a close look at the chin/throat area of the Side-blotched lizard on the left: notice the orange-tinge to the throat? Three sub-populations of males with different behavioral characteristics have been identified based on their throat coloration. Per californiaherps.com:

Orange-throated males – are dominant, aggressive and territorial and mate with many different females.
Yellow-throated males – do not defend territories. They mimic females and sneak past territorial orange-throated males to mate with their females.
Blue-throated males- guard their mates, chasing off the yellow males, but they are run off when confronted by orange males. Blue males also cooperate with neighboring blue males to protect their respective mates from the orange and yellow males, and their breeding is much more successful when they do so.

Pretty amazing stuff! Our arrogant orange-throated male certainly lived up to his reputation!

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Western Fence Lizard

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.


Okay, let’s change gears a bit and discuss one of our most familiar scaly faces, Sceloporus occidentalis, the Western Fence Lizard. These spiky little lizards can be found just about anywhere, including courtyards and city parks. They’re insectivorous, meaning they feed primarily on insects; larger males will, however, eat smaller lizards on occasion, even those of their own species! They are also important prey items for many species, including raptors and snakes. Western fence lizards can show a bit of variety in their behavior and coloration based on gender. The most striking differences in coloration occurs within the breeding season from March – June; during this time, males love to strut their stuff, showing off beautiful colors and performing physical ‘push-up’ displays to intimidate rival males and impress nearby girls. Male Western fence lizards, such as the one seen here, can have beautiful flecks of cyan on their dorsal scales. Let’s take a closer look:

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Here we can fully appreciate the dapper of a male Western Fence Lizard; just get an eye-full of that green!

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Now let’s take a look at the females: Female fence lizards tend to have a ‘dainty’ build when compared to the rather robust build of males and have a somewhat discreet pattern of dark, horizontal waves on the dorsum (back).

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A different female: Female Western fence lizards typically lay 1-3 clutches of 3-17 eggs that hatch after 60 days. Since Spring was the mating season, baby fence lizards should be making an appearance soon! Keep an eye out!

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Let’s look at other ways males can be distinguished from females: One of the most obvious visual differences occurs on the belly. The male, seen on the left, has areas of striking metallic blue on the lateral margins of the belly (2) and in the gular (chin) area (3)- hence the ‘blue belly’ moniker that is often applied to Western Fence lizards. Additionally, males will have more yellow in the thigh area and rather prominent femoral pores (1). These femoral pores secrete a waxy substance that is used to mark territory.The female, seen on the right, has greatly reduced blue markings (2,3) and much smaller femoral pores (1).

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Let’s have another look at those femoral pores and genital area: Within the blue box one can see a small, horizontal row of dots; these are the femoral pores. Notice the difference in prominence when compared to the female (pink borders). Also, take a look at the tail – notice the male has a thicker tail that bulges on either side (blue dots). These are the hemipenal bulges; they are absent in the females.
Next time we’ll take a look at another somewhat common species of lizard – and discuss a really neat defense mechanism!

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Pacific Gopher Snake

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.


Having introduced the only venomous snake in our area, let’s now take a look at a harmless species of snake that can be confused with the rattlesnake: The Pacific Gopher Snake (Pituophis catenifer catenifer) is perhaps one of the most commonly encountered snakes of the area. This large, nonvenomous snake can reach lengths of over 5 ft in length. It is a powerful constrictor that utilizes the strong muscles of its coils to asphyxiate its prey. Gopher snakes feed on small mammals (pocket gophers are a favorite), birds, and bird eggs. Smaller individuals will eat insects and lizards. The gopher snake has a few features that can easily lead one to mistake it for a rattlesnake, especially when exhibiting a threat display. Let’s learn how to distinguish the two:

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The pattern of the gopher snake at first glance can look remarkably similar to that of a rattlesnake; however, there are a few morphological (body shape) differences that can be used to distinguish the two. The most obvious, of course, is that the Gopher snake does not have a rattle. One of the defense mechanisms of this species, however, is to quickly vibrate the tip of the tail when alarmed – which can sound remarkably similar to a rattle when the tail comes into contact with surrounding vegetation! Secondly, gopher snakes have a much narrower head that is relatively indistinct from the neck. The rattlesnake, on the other hand, has a very wide, diamond-shaped head that is significantly wider than the neck. Again, things get tricky; an angry Gopher snake will adapt a defensive stance in which the head is flattened and the body is recoiled into an ‘S’ shape, like the specimen seen here.

There are other external features that less apparent from a distance that delineate the two: The gopher snake has round pupils (the black central portion of the eye) whereas the rattlesnake has vertical, slit-like pupils. The head scalation of the Gopher snake also consists of large, plate-like scales when compared to the much smaller, finer scales of a rattlesnake’s head. In the end, if there is any doubt as to what species of snake you are encountering, LEAVE IT ALONE!

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Rattlesnake – Part 2

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.


Okay, I promise this is the final bit about rattlesnakes, we will soon move on! Until then, however, let me share this specimen with you: This little guy was found at Montana de Oro and exemplifies the color and pattern variability of this species. Get a load of those striking gold eyes!

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Let’s examine the venom of rattlesnakes and how it is delivered! Rattlesnakes (and other vipers) have a unique type and pattern of teeth, known as a SOLENOGLYPH pattern which includes the following characteristics: The front fangs are very long – so long that, when the snake’s mouth is shut, the fangs fold flat in order to fit inside. They are also hollow, which allows venom to flow through them. They are, essentially, like two large needles attached to the front of the snake’s jaw. When the snake strikes, its mouth opens very wide and very fast; the folded fangs are sprung outwards into a position that allows for deep penetration into the tissue of the prey item.

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So what exactly is venom? Well, in the case of vipers (which includes rattlesnakes), their venom is actually a highly modified saliva that contains many strong protein chemicals known as ENZYMES that have a variety of actions. All animals contain enzymes in their saliva; however, the enzymes in viper venom are very, very strong. These enzymes, further divided into HEMOTOXINS (Hemo = blood) and CYTOTOXINS (Cyto = cells) are so strong that they can actually digest and dissolve blood and tissues, such as organs, muscles, and skin! This means that an animal (or person) who is unfortunate enough to get bitten by a rattlesnake will experience severe tissue destruction as far as the venom can reach. In humans, the bites of rattlesnakes are rarely fatal. They are, however, excruciatingly painful and, because the venom destroys tissue, some people who are victims of a rattlesnake bite and do not receive treatment quick enough may lose function of the bitten area – or worse. Severe bites can result in permanent disfiguration or amputation of limbs!

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Rattlesnake – Part 1

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.


Rattlesnakes belong to a subfamily of vipers known as Pit Vipers – I want you to look closely at his face; notice that, just to the side of his eyes, there are two large holes. These are what give “Pit Vipers” their name. These “pits” are actually sensory organs capable of detecting even the most minute of changes in temperature. They are, essentially, infrared cameras that allow the pit viper to “see” the body heat map of it’s prey. Let’s take a look at how they work!

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The mechanism of how these pits work is complex and a bit tricky to explain. The best way to think of these pits are as little “heat eyes”: The pits themselves are are composed of a thin, suspended membrane (think of a structure similar to your eardrum) that has a surface that is very, very sensitive to temperature. This surface essentially “sees” different temperature wavelengths and constructs a thermal image based on all of the temperatures in range, similar to the image seen here. Interestingly, these pits are also found in other types of snakes, including some species of pythons and boas!

There are three hypothesized advantages to snakes that have these pits: The first is rather obvious based on the picture; the snake can locate its prey much easier! Similarly, predatory animals will also be “seen” with greater accuracy, helping the snake to avoid them, if possible. Finally, snakes, like all reptiles, are cold blooded. This means that snakes must regulate their body temperature in accordance with the external temperature. If a pit viper, for example, is feeling too hot, it can simply “see” where the cooler area is and move there!

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Reptiles, Amphibians, and Birds of the Central Coast

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.

Dr. Anthony Colbert
Dr. Anthony Colbert

Here we have a beautiful example of Crotalus oregonus oregonus, the Northern Pacific Rattlesnake. This species is the only venomous snake found in central California and is an incredible animal! Adults can reach nearly 5 feet in length; however, an adult size of 2.5-4 feet is much more common. Like all snakes, the Northern Pacific Rattlesnake is a carnivore, meaning that this species only eats meat. Smaller individuals will feed on lizards, frogs, and insects; adults will eat birds, ground squirrels, mice, rats, and rabbits. As far as rattlesnake species go, the Northern Pacific Rattlesnake is rather mild-mannered. Contrary to popular belief, the rattlesnake will usually only bite if startled, cornered, or provoked. When happened upon, most rattlesnakes will normally try to avoid confrontation by making a slow retreat into a nearby hiding place.

snake7In a bit, we’ll take a closer look at some of the features that make the rattlesnake such an amazing animal!