First described in 1861 by American palaeontologist Edward Cope—something of a prodigy—the rosy boa is a magnificent snake. It comes in many colors. While there is some taxonomic dispute about Latinate forenames and phylogenetic jargon, the scientific world is largely united on this: the rosy boa is a very cool critter.
In brief, the rosy boa morphs which occur commonly, in the wild are as follows:
- Mexican Rosy Boa (Lichanura trivirgata trivirgata)
- Desert Rosy Boa (Lichanura trivirgata gracia)
- Coastal Rosy Boa (Lichanura trivirgata roseofusca)
More detail on these below, but first, a general introduction, and some…
It is a relatively small, non-venomous, carnivorous boa, normally reaching a total length (inclusive of tail) of 24-34 inches (60-86cm). As such, it is a lightweight snake—not like its cousin, the boa constrictor!
A rosy boa can live for over 15 years, if cared for properly, and will reach adulthood in 3 to 4 years.
Its width, when fully grown, is similar to that of a golf ball, and its color scheme varies dramatically, more than almost any other snake. Each subspecies is also fairly geographically confined to a certain area, which means you can often predict the genus of a rosy boa from where it was spotted.
Having said that, you may well find that two rosy boas, living within a dozen miles of each other, look completely different!
Where Do They Come From?
The rosy boa originates from coastal southern California, USA, and Baja California, Mexico. (Imagine an arm of land continuing from where California turns into Mexico—that’s Baja California) Its name derives from the pinkish streak that runs down the belly of specimens from these areas.
What Sets Them Apart From Each Other—And From The Rest?
Most rosy boas show some semblance of the instantly recognizable three stripes which run longitudinally down its back and lower sides. Variations in these stripes are a key indicator of subspecies. Some lines are dotted, some thick and clear-cut; some stand out like road markings, others seem to blend and pixellate into the surrounding skin. These stripes range from dark, blackish browns and maroons to pale orange.
Highly specific and unique, these colorful creatures have become highly desirable. Indeed, they have become collectors’ items, among herpetologist enthusiasts. As a result, their genetic variance has become a playground for captive breeders. Because their pattern designs are so unique and stark in contrast, there is a high chance of successful cross-coloration!
Where Do They Live?
Rosy boas of several subspecies are currently found, in the wild, in California, Arizona (US), Baja California and Sonora (MX), in the Mojave and Colorado Deserts but also in coastal areas along the stretch from LA County to the Mexican border.
Population statistics for rosy boas are either old or conjecture. One estimate puts their number at 100,000; others are higher. While there are no concrete numbers, they are listed under “Least Concern” by the IUCN Red List, which is good. In 2008, California State listed them as “sensitive”, but considers the population stable.
What Are They Like In The Wild?
In the wild, the rosy boa moves very little—indeed, it is one of the slowest snakes in the world. It waits for prey to come within inches of its hiding place, and then strikes with incredible precision. Its usual prey is small mammals, such as deer mice and kangaroo rats.
Primarily nocturnal, it spends much of its time concealed from the outside world, hidden from the view of predators and the scorching sun. Granite outcroppings and rock formations provide ample shelter, as do volcanic rocks. This docility is part of the reason it is so popular as a pet—rosy boas are typically unaggressive, amenable creatures!
What, So, They’re Perfect Pets?
In many ways, yes! They are generally docile, unaggressive and pocket-sized. Well, not pocket-sized, but small enough so that little Wendy doesn’t fear for her life when she takes him out of his enclosure.
Owing to the popularity of other species, rosy boas haven’t established themselves as popular house pets yet. But that could easily change, as they are frequently captive-bred, and growing in popularity.
Great, 3 more questions
Where Can I Buy One? How Much Do They Cost? And What Should I Feed It?
There are multiple online sellers of rosy boas, or you can go into a store, or direct to a breeder. You’ll also need a terrarium—10 or 15 gallons (35-55L) should suffice.
Because of the level of genetic variance and rarity of certain morphs (keep reading to find out more about this!), prices range dramatically. You could pay as little as $25, or as much as $2200!
As a rule, they are happy feeding on frozen rodents, warmed to room temperature—appropriately sized! Remember, these aren’t large snakes. Do not use a microwave, and do not prepare the rodents in the same place that you cook your own food!
Juvenile snakes need feeding once per week; adults can go a bit longer. Make sure to provide a bathing bowl (large enough to soak in), filled with chlorine-free freshwater.
OK, OK… How Many Rosy Boa Morphs Are There?
Good question. There is no concrete answer, for a few reasons.
- Firstly, there are disputes over whether two subspecies are in fact different at all – sometimes, subspecies, or morphs, are so similar that there are scientists who argue they are not distinct at all.
- Secondly, no one can keep track of all the rosy boa morphs in the wild – naturally occurring genetic deviations occur without observation! Examples include albinism or anerythrism (absence of red pigment).
- Finally, it is also difficult to stay up date with all the captive-bred variations which, in turn, can be split into two categories:
- “Designer” morphs, which result from the genetic confluence of two pre-existing rosy boa morphs, e.g. snow rosy boa
- Selectively bred morphs, which exist because of the manipulation of patterns and colors via artificial selection, over multiple generations, with a particular goal in mind.
With that in mind, let’s take a closer look at the three most common rosy boa morphs in the wild.
Mexican rosy boa (Lichanura trivirgata trivirgata)
Native to: western Sonora and southern Baja California, Mexico, plus a population in and around the Maricopa Mountains in Arizona.
Price: $80 ($50-150).
What does it look like? Whitish, yellow-white or off-white base color, with three thick black (or very dark gray-brown) stripes running from its eyes to the tip of its tail. Stripes are almost equal in thickness—classic stripe.
Anything else? This is the nominative subspecies, i.e. the rosy boa most typically representative of the species as a whole. It was the first to be discovered and named. This explains the repeated second word in its Latin name. Some people call them ‘Triv trivs’, or simply ‘rosy boas’.
Desert rosy boa (Lichanura trivirgata gracia)
Native to: Southern California and southwest Arizona.
Price: $90 ($50-150).
What does it look like? Somewhat larger than their Mexican cousins, desert rosy boas have lighter patterning, rosy pink or light brown, on a cream base. The subtlety of their pattern helps them blend into their desert surroundings.
Anything else? Found in desert areas and scrubland, anywhere where there are rocky outcroppings, cacti and canyons.
The desert rosy boa is sometimes called the Morongo Valley rosy boa, because it is most often found in this location. Its natural range is located in San Bernardino County, in California, at the centre of which lies the Morongo Valley.
Coastal (California) rosy boa (Lichanura trivirgata roseofusca)
Native to: West coast of Baja California (Mexico) and California. As such, they can sometimes be found in the vicinity of the nominative species.
Price: $100 ($60-200)
What does it look like? Coastal rosy boas are the darkest of the three, but also the most variable, in pattern and overall color. They can have red stripes on cream background, orange or brown stripes on a bluish-gray background, or even pink stripes. Their stripes are dotted, or pixelated, as if painted on, in the pointillist fashion.
Anything else? They may be known as ‘coastal’, but this rosy boa morph has been spotted at a height of 6000 feet (1800m) above sea level!—way up in the San Bernardino Mountains.
Other, Less Common Rosy Boa Morphs
As I mentioned earlier, there are a plethora of other morphs out there, from colorful to plain, uncommon to extremely rare. Here I will provide a brief description of each.
First, two rosy boa morphs about which there is some controversy. Some argue that, because they are so similar to other, more established subspecies, they should not be treated as separate morphs at all:
Lichanura trivirgata myriolepis
In the absence of a common name, we have to use the full Latin title. You can call these myriolepis rosy boas, for short.
They are almost indistinguishable from coastal rosy boas. If you look very closely, you will see that they are typically more orange, and have a more distinct stripe pattern. They are only available from a few breeders.
Price: $150 ($100-200)
Lichanura trivirgata bostici
Again with the Latin name—but you can call them bostici rosy boas. These boas are similar in size and shape to Mexican rosy boas, their stripes are just ever so slightly slimmer. Hence, some people argue they are not different at all.
Albino rosy boa
Albinism is defined as the “congenital absence of any pigmentation or coloration […] resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish.” As such, albino rosy boas are rather less ‘rosy’ than their name suggests.
Albino rosies are naturally occurring, but used frequently during experimental captive breeding programs. They are vivid orange, or cream, and have bright red eyes.
Price: Approx $200
Anerythristic rosy boa
Anerythristism is a condition whereby an animal lacks red pigment. Anerythristic rosy boas vary widely in appearance: some have bright blue eyes; others have jet black eyes. Some are dark blue in color, with brown stripes; others are an off-white, lavender-cream color, with no stripes.
Price: Approx $80
Axanthic rosy boa
These snakes are uncommon – difficult to find among both pet stores and breeders. Try looking online. Because they’re hard to find, you might have to pay a bit more for one.
Dark in color, exhibiting gray and brown hues.
Hypomelanistic rosy boa
Highly variable in appearance, these rosy boas have diffused stripes. For this reason, the snake’s pattern appears fuzzy or blotchy, and stark in contrast.
They are variable in appearance, but tend to be cream with brownish red coloration.
Snow rosy boa
Like albinos, this rosy boa loses its dark pigmentation. This beautiful morph is a combination of albino and anerythristic snakes. As such, their coloration has a mystical quality – they can be anything from cream-silver to silver-white. Lacking both general pigmentation and red pigmentation, they are lighter in color than albino rosy boas.
Price: Minimum $200
Moonglow rosy boa
The combination of a snow rosy with a hypomelanastic rosy, ‘moonglow’ rosy boas are very rare—the rarest of this list. Now you get an idea of how captive breeders can create new subspecies, simply by finding genetically compatible combinations between the pre-existing morphs!
Price: As yet unavailable—you’ll have to be patient!
Very Rare, Anomalous, Early-Days, Under-Development or Contestable Rosy Boa Morphs
- Picasso – very rare
- Development started in 2003, subspecies emerged 2014
- Combination of selective breeding and natural morph introduction
- Two pastel-yellow stripes and three lilac stripes—the lilac stripes turn light green with age
- Deep red eyes
- Pearl – very rare
- Iridescent pearl color
- Very faint light gray outline of a pattern
- Enchanting jet black eyes
- Ivory – very rare
- This one-off snake was the result of a long term breeding project. It has a white-rose hue, with minimal patterning
- Two slim, broken yellow stripes running either side of the centre of its back
- Mono-Stripe Albino – under development
- Yellow-white background and displaying a smattering of lavender speckles, very light and sporadic
- Mono-stripe trait refined over many generations in order to eliminate fully the two lateral (side) stripes
- Ghost / San Flipe Hypo – rare, selectively bred
- In the vernacular, the term “ghost” is used to designate a snake bearing and exhibiting the genetic combination of hypomelanism and anerythrism, thus making it almost patternless!
- Cream overlaid with tan dorsal (on top) stripes and a faded, almost transparent-looking lateral stripe, very washed-out appearance
- Atkinson Albino Ajo – early-days
- Bizarre, unique and mesmerizing pattern
- Paradox Albino – natural anomalous
- Albino Whitewater: “Goldeneye” – contested
- Albino Coastal – early-days
- The albino coastal rosy boa is remarkable for its large size and extreme orange jagged speckling and striping
- Very vivid in its patterning
- Pure red eyes
- Discovered to be genetically incompatible with the Albino Whitewater subspecies in 2002
- Calico Coastal, Calico Corn Springs and San Ignacio Axanthic
- Anomalous and contestable, as they have yet to be confirmed as having a unique and inheritable trait
To Sum Up…
So which rosy boa is the best match for you? Well, that depends on your budget, and how colorful you’re feeling.
One thing is for sure, there are a wonderful variety of rosy boa morphs out there, and more subspecies popping up by the decade. These calm and amenable snakes make for a good first choice if you’re thinking of owning a snake. Remember, each one is unique—so treat them with care!
Which one do you like best?
Thanks to Michael Goldberg’s invaluable resource on Rosy Boa Morphs (link), without which this article would not have been possible.
I was originally commissioned to write this guide for Exo Pet Guides. However, their version – along with every article I ever wrote for them – falsely credits a different author.