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The Natural History and Captive Care of the Black (Eastern) Ratsnake, Elaphe (obsoleta) alleghaniensis

Black Rat Snake
Overview
The black rat snake and the related corn snake, E. guttata, were among the first to become firmly established in North American herptoculture, and remain pet trade staples. At least 11 species of the genus Elaphe are found throughout North and Central America.

The taxonomy of this genus is confusing due to a wide variation in the appearance of individuals of the same species, and to the fact that different species inter-breed where their ranges overlap. The black ratsnake was formerly known as E. obsoleta, but that name is now assigned to the Western ratsnake. Recently, genetic evidence has shown that many North American ratsnakes should actually be classified within the genus Pituophis, along with the bull, gopher and pine snakes.

Physical Description
Although usually a uniform black in color, with an off-white underside, some individuals show traces of dark gray blotches and stripes. Juveniles differ markedly from adults, being pale gray and strongly patterned in dark gray or brown. Hobbyists have developed a number of unique color morphs, including albino individuals, and frequently hybridize this snake with related species. Black ratsnakes average 3 – 5 ½ feet in length, with the record holder being a giant of 8 ½ feet recorded from Westchester County, NY by noted herpetologist Raymond Ditmars.

Black ratsnakes living from North Carolina through the Florida Keys vary greatly in appearance from northern specimens, being various shades of yellow and orange in color. Formerly classified as distinct subspecies, known as the Everglades’s ratsnake and yellow ratsnake (both popular in the pet trade), they are now considered to be local color variations of the black ratsnake.

Range and Habitat
Black ratsnakes occupy much of Eastern North America – from SW New England and S Ontario to the Florida Keys and from SW Wisconsin to Oklahoma and N Louisiana. Happily for NYC-based “herpers” such as I, they are still to be found within NYC limits (parks in the Bronx and Staten Island), and in suburban Long Island and Westchester. Quite adaptable as regards habitat, they utilize forests, fields, rocky hillsides, swamps and overgrown suburban lots. It is one of many snake species drawn to farms, stone walls, trash dumps and abandoned buildings in search of mice and rats. In some habitats, black ratsnakes are highly arboreal and shelter in tree hollows.

Status in the Wild
Population levels appear stable in most areas, although the species is listed as of “Special Concern” in Minnesota and elsewhere. It adjusts well to some human presence and, if left alone, may become common on farms and near refuse disposal areas. Large scale captive breeding has removed collection pressures from wild populations.

Diet
Black ratsnakes are powerful constrictors. They tend, as adults, to focus on mammalian prey such as squirrels, chipmunks, rabbits, bats, voles, deer mice, rice rats, small opossums and similar creatures, but also take birds and their eggs. Young snakes include lizards, frogs and large insects (i.e. cicadas) in their diet.

A colleague of mine observed 6 foot-long (yellow-phase) black ratsnake attempting to constrict a white-tailed deer fawn on St. Catherine’s Island, Georgia. The fawn, which might have set a new “snake swallowing record” had it been overcome, eventually escaped.

Reproduction
Mating occurs from March to May, with 6-30 eggs being laid 27-28 days thereafter. Second clutches, laid in August, have been reported in captive situations but not in the wild. The eggs are secreted in cavities below fallen trees and rocks, or within rotting logs and stumps. The young, 11 – 13 ½ inches in length, hatch in 47-85 days.

Miscellaneous
The black ratsnake frequently shares hibernation dens with rattlesnakes, copperheads and other species. In some parts of the country it is known as the “pilot blacksnake” or “rattlesnake pilot”, in the mistaken belief that it guides rattlesnakes to their winter retreats.

Black Ratsnakes as Pets

General
With their moderate size and even temperaments, black ratsnakes make excellent pets. They are hardy enough for beginning hobbyists, and yet are so interesting that even well- experienced keepers often reserve a place for 1 or 2 in their collections.

Space and Other Physical requirements
Black ratsnakes do well in glass terrariums or aquariums which, ideally, should be a bit longer than the snake itself and as wide as possible. Be sure to secure the tank’s screen top with cage clips, as snakes are notorious escape artists. Cypress mulch or other substrates designed for use with snakes should cover the cage bottom. A reptile-safe disinfectant should be used to swab the cage floor after the snake defecates.

Rat snakes appreciate a shelter in which to hide and a bowl large enough for soaking. The water bowl should be filled to a level such that it will not overflow when the snake enters, as damp terrarium conditions may lead to respiratory and skin infections. If space permits, a stout branch for climbing and basking should be included.

American hobbyists favor a fairly “sterile” set up for rat snakes, but in Europe they are commonly kept in large, planted exhibits. Black ratsnakes take well to these, and, while management is a bit more complicated, the range of behaviors exhibited by snakes in such settings makes the undertaking well-worthwhile. I shall write more about keeping snakes in naturalistic exhibits in a future article.

Light, Heat, Humidity, etc.
Cage temperatures should range from 75 – 82 F, with a basking spot of 88 – 90 F. This species has no need for UVB light, but full spectrum lamps emitting UVA may be of some value. The cage should be kept dry at all times (see above).

Feeding
Black ratsnakes thrive on a diet of mice and rats. They take readily to dead prey and should not be offered live rodents due to the likelihood of injury to the snake. Adults should be fed every 7-10 days.

Captive Longevity
The captive longevity record for this species is just over 34 years.

Handling
Although black ratsnakes will, like most animals, bite in self-defense, they are, as a whole, mild-tempered. Most respond well to gentle handling, but individual animals vary greatly in this regard. Never startle a snake by picking it up suddenly, and do not handle snakes after you have touched food animals. Future articles will deal with the specifics of handling in detail.

Breeding
Breeding will be covered in depth in a future article. Except for snakes originating in the southern-most portions of the range, black ratsnakes breed most reliably when subjected to a winter cooling period. This species has been bred in captivity through multiple generations.

Miscellaneous
A number of European and Asian relatives, such as the Russian ratsnake, E. schrencki, may be kept as described for the black ratsnake. Other species referred to as “ratsnakes”, such as the arboreal red-tailed ratsnake, Gonyosoma oxycephala, have slightly different husbandry requirements. Please be sure to research potential pets carefully, as trade names can be misleading.

Additional Resourceshttp://people.wcsu.edu/pinout/herpetology/eobsoleta/index.html (detailed information on natural history)

21 comments

  1. avatar

    Hi Frank:

    Maybe you can help; I almost ran over a snake yesterday and am trying to figure out what kind of snake I (just!) missed. It was shiny black with regular yellow blotches (not stripes). Approx as long as the length between 2 front tires (I really thought I was going to run over one end!). I’m in Westchester NY, and after coming across your blog I am pretty sure it was a Black rat snake, but figured I’d ask.

    Alli

  2. avatar
    Frank Indiviglio

    Hi Alli,

    Thanks for your comment.

    I believe you are correct in identifying the snake you saw as a black rat snake. The snake you describe was just about at the size where it would still have a blotched pattern (as they mature, the color goes to all black). Black rat snakes are no longer common in Westchester, but have managed to hold on better than have other large species (the record specimen, 8.5 feet long, was collected there). The largest I have come across in the county (I am a New Yorker) was just over 5 feet.

    The other large black snake that is sometimes encountered there is the black racer, but juveniles do not have a blotched pattern. Timber rattlesnakes are still occasionally to be found in Westchester also – there is a black and a tan form, and some speciemens resemble juvenile rat snakes, but they are quite rare now (and very stocky in build).

    The identification of reptiles in the field is complicated by the existence of large numbers of escaped and released pets. I have found an African pancake tortoise in Breezy Point Park, Queens, a South American red-footed tortoise in a park on Long Island, 12 foot long Burmese pythons living for years in buildings in the Bronx, a reticulated python (in the process of swallowing a cat!) in Brooklyn , and so on. Florida leads the country in introduced species – Burmese pythons, Nile monitors, green iguanas and scores of other reptiles and amphibians are breeding there, as well as at least 80 species of non-native fish, and a good number of birds and mammals.

    Thanks again for your interest – I’m always happy to hear about animal sightings.

    Best regards, Frank

  3. avatar

    Frank –

    What a great website and resource for pet owners. I have had some reptiles when I was younger, and have been known to catch the occasional snake that wanders through our or a neighbor’s yard. A couple of weeks ago, I caught a juvenile black rat snake in our garage. It’s approximately 13″ long now, and I have it in a ten gallon aquarium. I know that black rat snakes can reach five to six feet in length, but I don’t know how quickly they grow. How quickly do you think that the snake will out grow this current tank?

    Jonathan
    =====================================

  4. avatar

    Hello Jonathan, Frank Indiviglio here.

    Thanks for the kind words; much appreciated

    Growth rates vary widely among different populations and are also heavily influenced by diet. Snakes seem able to adjust their metabolisms to food availability; black rat snakes have even been observed to add size during experimental fasts lasting several months! You may be able to get away with the tank for 6-12 months or so; wild caught snakes sometimes go off feed in winter, even if kept warm.

    If the snake seems to grow quickly, it would be best to go right to a 29 gallon for its next home, as a 20 may also be too small in time. Especially large adults will need a 55 gallon or larger tank.

    Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

    Best regards, Frank Indiviglio.

  5. avatar

    Frank –
    A little update on our rat snake Stanley. He is doing well. He has shed twice, he is about 16″ now, and is now taking frozen fuzzies. I think he might be hibernating of sorts. He is mostly in hiding, only occasionally coming out during the day. He is still occasionally snappy when I try to pick him up, but for 90% of the time he is fine.

    Jonathan
    ============================

  6. avatar

    Hello Jonathan

    Thanks for the update and glad to hear the news. You may need to change his feeding schedule if temperatures drop at night; if you’d like further info, please send me some details re day/night temperatures.

    Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

    Best regards, Frank Indiviglio.

  7. avatar

    Hey frank,

    I got a everglades rat snake a while ago and she’s still pretty much a baby, so I was just wondering how often should I feed him? I mean I’ve been doing it every seven days, but I’ve read that when their young three to four days days works. Is that safe? I have the same exact question for my “pretty much a baby” rainbow boa too, is every four days or so okay?
    thanks so much sir, you truly bring me peace through your knowledge, always answering my questions

  8. avatar

    Hi Michael,

    Thanks for the kind words. Both snakes are favorites of mine, Once weekly is fine…snakes are very effective at utilizing their food, and captives expend little energy moving about, hunting etc. There are n=many feeding strategies that can be used, but billions have been successfully raised on once weekly feedings. Enjoy, pl keep me posted, Frank

  9. avatar

    Do black rat snakes tend there eggs as they incubate like pythons do ?

  10. avatar

    Hi Jon,

    That has not been observed. Have you seen anything to suggest it?

    Best, Frank

  11. avatar

    Hey. I just recently uncovered 12 snake eggs in rotted bales of straws I was moving around. All indications are Black snake…king snake…rat or corn snake. Did not see an adult around. I saved them along with a lot of the damp moist straw in an aquarium. I am monitoring the temperature along with the moistness of the straw. Any other advice to keeping them healthy an well? I have always been a snake fan and I would love to keep these guys alive.

  12. avatar

    Hi Mark..thanks for the note, brought back some fond memories.

    You can use straw, although there is a tendency for fungus to develop. Vermiculite is safer in this regard, and also allows oxygen to penetrate below the eggs; sphagnum moss works well also. But the eggs will likely hatch soon, so you may be fine staying as is. watch for fungus, and let me know if you see anything suspicious.

    Covering the aquarium with plastic will keep humidity up, if needed..please see this article for some tips…can be applied to an aquarium incubator. No need to weigh etc at this point. Best not to handle, as skin-oils can block pores.

    Be sure lid is well-secured…use 6-8 cage clamps or duct tape until you are sure of species, etc…most hatchlings can squeeze through surprisingly small gaps. With the exception of coral snakes, all venomous native species in the USA are live-bearers.

    Please keep me posted, interested to hear what you have found (where are you located?), enjoy, Frank

  13. avatar

    Hey Frank. New to blogging,and ended up replying to email and not blog. Very good information thanks. As I mentioned in email one egg was damaged and I opened it and saw a translucent snake heart beat and all ten inches long coiled up. I will be keeping everybody up to date as time progresses with the hatchlings. Stay tuned…thanks again

  14. avatar

    I have a 5 foot black snake I got beginning of spring. It’s been eating rats pretty regularly since then. The last two weeks it hasn’t shown any interest in food. It’s in my basement and the temperature has dropped about 10 degrees down here since summer, however the lights on the terrarium haven’t gotten any different and the other snakes I have don’t seem affected and are still eating fine. I Was wondering if I’m dealing with some sort of biological clock issues here where it knows its typically the time of year it should go into hibernation. If that’s the case what is the best course of action? Do I remove lighting and put it in a dark corner for a month or so or just keep everything the se and not allow it to actually hibernate? Or will it do it regardless of all factors? Is it necessary for their health to hibernate or is it just a defense mechanism from the cold? So lots of questions on the hibernation end of things and how I should or shouldn’t handle it…

  15. avatar

    Hi Jeremiah,

    Assuming there’s no underlying health prob, it almost certainly is due to a biological clock/circadian rhythm reaction; especially common in wild caught animals, but can occur in CB…can be affected by origin of parent stock, etc. I’ve kept bl rats and northern watersnakes at 58-65 for the winter, with access to a water bowl; digestive tract needs to be empty. They move about a bit but do not lose weight….many snakes can regulate metabolism to fit food availability…black rats have even been shown to grow during enforced fasts of 3-4 months! Some prefer to keep them warmer..i.e. with a basking spot but in a cool room; benefit of this is that immune system functions better than when very cool. Chilled animals are sometimes afflicted by health problems that would otherwise be kept in check. Let me know what temps you have for ambient and basking…might be safest to leave as is, esp. if you have a WC individual (parasites will be present); it will not lose significant weight, perhaps none at all, if it has been feeding regularly. Hibernation seems not necessary for health in general, but most temperate species do need a cool period if they are to breed. Normal room fluctuations may be enough in some cases. Pl keep me posted, best, Frank

  16. avatar

    Hi Frank –

    Another update and a question about our pet Stanley. It’s been about two years since I found him as a baby, and he is now about 32″ long, and doing very well. He has been eating large mice very easily and quickly. I have been feeding him about every 10 days. I think it’s time to start feeding him small rats. I tried feeding him a frozen one today, but he didn’t seem interested in eating it. He smelled it a lot, but he didn’t eat it. Should I wait and try again, or go back to the mice, but feed him more frequently? Also, since he has only eaten mice, could the new smell of a rat be strange to him?

    Thanks again!

  17. avatar

    Hi Jonathan,

    They often prefer one of the other. No need to use rats. Add an extra mouse if need be, but only if snake appears hungry, restlesss etc; they are very efficient at processing food, and are not expending much energy in most captive situations. Enjoy, best, frank

  18. avatar

    Thanks Frank, for all your interesting and educational articles!

  19. avatar

    My pleasure, thanks very much for the kind words. Please keep me posted, enjoy, Frank

  20. avatar

    just caught a juvenile black rat snake in southern Indiana. it is 10 inches long. the month is October. I guess that part about only having a second clutch in captivity isn’t quite right.

    although it has been som mighty peculiar weathe we have had this last winter and this whole summer too. really cold winter followed by a cool wet summer

  21. avatar

    Hello,

    Thanks for this observation. It’s difficult to judge age by size, as growth is affected by so many factors. However, there are a few anecdotal reports of doble clutching in the wild, so it could very well be that you’ve seen a recently hatched animal. Best, frank

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About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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