Animal Diversity Web

Ge­o­graphic Range

Store­ria oc­cip­it­o­mac­u­lata, the red-bel­lied snake, ranges from east­ern North Dakota to Nova Sco­tia, south to Florida, and west to east­ern Texas. The Great Plains may act as a bar­rier to the west, con­sid­er­ing that they are also ab­sent from large areas of rem­nant prairie lands in the parts of the mid­west and east. How­ever, a sub­species, Store­ria oc­cip­it­o­mac­u­lata pa­has­apae, is found in dis­junct pop­u­la­tions in the Black Hills of west­ern South Dakota and east­ern Wyoming. An­other sub­species, Store­ria oc­cip­it­o­mac­u­lata ob­scura, is found in Florida and west along the Gulf Coast to east­ern Texas. Red-bel­lied snakes are lo­cally com­mon in wood­lands through­out their range (Hard­ing 1997, Smith and Brodie 1982).

• Biogeographic Regions
• nearctic
  • native

Habi­tat

Red-bel­lied snakes are most abun­dant in de­cid­u­ous and mixed wood­lands. They gen­er­ally like a damp, moist, and cool en­vi­ron­ment. Un­sur­pris­ingly, they are often found in mesic en­vi­ron­ments, such as river bays, creek bot­tom­lands, and sphag­num bogs where slugs, snails and worms are read­ily avail­able. They often hide under bark, logs, rocks, and leaf lit­ter. How­ever, they are still com­mon in drier sites such as pas­tures and grass­lands ad­ja­cent to wood­lands (Hard­ing 1997, Sem­l­itsch and Moran 1984). Quite often they are seen around human habi­ta­tions. They tend to hide in va­cant lots around trash, under boards, and other de­bris. Oc­ca­sion­ally red-bel­lied snakes are seen bask­ing in the open sun and some­times climb into low shrubs and other veg­e­ta­tion (Hard­ing 1997).

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• forest

• Wetlands
• marsh
• bog

Phys­i­cal De­scrip­tion

The red-bel­lied snake is a very small snake; total body length ranges from 20.3 cm to 40.6 cm (8-16 in) when fully grown. They are usu­ally brown to red­dish brown (al­though some­times gray and rarely black) with or with­out 4 faint, dark dor­sal stripes. Oc­ca­sion­ally there will be only one, light col­ored, mid­dor­sal stripe, or all five stripes may occur to­gether. The belly is usu­ally a strik­ing bright red, but is known to occur in or­ange, faint yel­low, pink, and in­fre­quently in gray or black. The head is usu­ally brown or red­dish brown on top with a white throat and chin un­der­neath. There are three light spots around the neck (one on top and one on each side) that can mix to­gether to form a col­lar. There are 110-133 ven­tral scales and 35-61 cau­dal scales. The mid­body con­tains 15 scale rows. They have keeled scales and a di­vided anal plate. (Behler 1979, Hard­ing 1997, Smith and Brodie 1982).

Red-bel­lied snakes are just 7-11 cm at birth. Com­pared with adults, new­born snakes are darker above and lighter below, and the nape spots cre­ate a more dis­tinct neck col­lar (Hard­ing 1997).

Dis­tin­guish­ing the sex of red-bel­lied snakes is dif­fi­cult un­less the fe­male is preg­nant and there­fore heav­ier and larger. How­ever, males gen­er­ally have longer tails than fe­males. The fe­male tail is ap­prox­i­mately 17-22 per­cent of the total body length and the male's tail makes up 21-25 per­cent of the total body length (Hard­ing 1997).

Store­ria oc­cip­it­o­mac­u­lata sub­species are also hard to dif­fer­en­ti­ate. Some have been know to hy­bridize, and there­fore con­tain char­ac­ter­is­tics of both par­ent species (Hard­ing 1997). How­ever, the Florida red-bel­lied snake, Store­ria oc­cip­it­o­mac­u­lata ob­scura, usu­ally has a more dis­tinct neck col­lar (neck spots more com­pletely fused), while Store­ria oc­cip­it­o­mac­u­lata pa­has­apae of the Black Hills re­gion has very small, faint necks spots or they are com­pletely ab­sent (Behler and King, 1979).

Red-bel­lied snakes can be con­fused with brown snakes, Kirt­land's snakes, ring-necked snakes and garter snakes. How­ever, red-bel­lied snakes are usu­ally much smaller than these species. Kirt­land's snakes also have a red belly, but it con­tains two rows of black spots. Ring-necked snakes have a more uni­form, promi­nent col­lar and they have smooth (rather than keeled) scales. The brown snake has a light belly and 17 mid­body scale rows. Garter snakes also have a lighter belly and an un­di­vided anal plate (Hard­ing 1997).

• Other Physical Features
• bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

• Range length

  20.0 to 40.0 cm

  7.87 to 15.75 in

Re­pro­duc­tion

• Mating System
• polygynous

Red-bel­lied snakes typ­i­cally mate in spring and early sum­mer, but may also mate in late sum­mer and fall. They give birth to live young usu­ally be­tween late July and early Sep­tem­ber in north­ern re­gions and some­times later in the south. Lit­ter size ranges from 1-21, but nor­mally only 7 or 8 are born (Hard­ing 1997), with ap­prox­i­mately equal num­bers of each sex (Blan­chard 1937). The largest fe­males in­vest more en­ergy in re­pro­duc­tion, pro­duc­ing a higher num­ber of young (but not nec­es­sar­ily larger young) than smaller fe­males (Brodie and Ducey 1989). Stud­ies have shown that nearly all fe­males cap­tured in the spring are gravid, sug­gest­ing that they are very suc­cess­ful breed­ers (Sem­l­itsch and Moran 1984).

New­born snakes grow quickly, often dou­bling their length within the first year (Hard­ing 1997). By their sec­ond year they are sex­u­ally ma­ture and begin mat­ing. Min­i­mum length for sex­ual ma­tu­rity is 22 cm (Blan­chard 1937). It is not known how long they live in the wild, but cap­tives may live at least four years (Hard­ing 1997).

• Key Reproductive Features
• iteroparous
• seasonal breeding
• sexual
• fertilization
  • internal
• ovoviviparous

• Breeding interval

  Red-bellied Snakes breed once or twice each year.

• Breeding season

  Red-bellied Snakes have their young in late summer and fall.

• Range number of offspring

  1.0 to 21.0

• Average number of offspring

  7.0

• Average age at sexual or reproductive maturity (female)

  2.0 years

• Average age at sexual or reproductive maturity (female)
  Sex: female

  730 days

  AnAge

• Average age at sexual or reproductive maturity (male)

  2.0 years

• Average age at sexual or reproductive maturity (male)
  Sex: male

  730 days

  AnAge

Fe­male Red-bel­lied Snakes nur­ture their young in their bod­ies until they are born. At that point there is no fur­ther parental care.

• Parental Investment
• precocial
• female parental care

Lifes­pan/Longevity

Red-bel­lied Snakes have been known to live 4 years in cap­tiv­ity. They may live longer in the wild but this is poorly known.

• Range lifespan
  Status: captivity

  4.0 (high) years

• Average lifespan
  Status: captivity

  4.6 years

  AnAge

Be­hav­ior

Red-bel­lied snakes are typ­i­cally di­ur­nal, but may be­come noc­tur­nal dur­ing hot or dry weather. They tend to be more ac­tive after rain­fall, most likely be­cause their main prey is more ac­tive at these times (Hard­ing 1997). How­ever, in South Car­olina sur­face ac­tiv­ity was found to in­crease dur­ing pe­ri­ods of hot dry weather and low water lev­els. This is pre­sum­ably be­cause dry­ing of their home range forces them to seek moist areas to es­cape des­ic­ca­tion and to find slugs, snails, and worms. Dur­ing this type of weather red-bel­lied snakes may be en­coun­tered more often be­cause they are forced to fol­low soil mois­ture gra­di­ents (Sem­l­itsch and Moran 1984).

Red-bel­lied snakes are quite cold tol­er­ant, as many are lo­cally com­mon in north­ern por­tions of their range. They re­main ac­tive year-round in the south and from April to Oc­to­ber or No­vem­ber in the north. In the north ac­tiv­ity may in­crease dur­ing large mi­gra­tions to and from hi­ber­nat­ing sites. They hi­ber­nate un­der­ground in anthills, build­ing foun­da­tions, aban­doned an­i­mal bur­rows, and other suit­able cav­i­ties. They usu­ally hi­ber­nate in large num­bers with their own kind as well as with other snake species (Car­pen­ter 1953, Hard­ing 1997). An ex­ca­vated ant mound in Man­i­toba Canada yielded 257 hi­ber­nat­ing snakes of which 101 were red-bel­lied snakes, 148 smooth green snakes and 8 Great Plains garter snakes (Oliver 1955).

The red-bel­lied snake ex­hibits a cu­ri­ous be­hav­ior known as "lip-curl­ing." While both in­gest­ing prey and being threat­ened, they flick their tongue and curl their lips up­ward to show their small max­il­lary teeth. This is thought to have some ben­e­fit for prey seizure, but it may be just as im­por­tant as a de­ter­rent to preda­tors. When han­dled roughly they will some­times ex­hibit the lip-curl­ing, then rub their head side­ways on the cap­tor scratch­ing their teeth against the flesh. The teeth are too small for this to be harm­ful to hu­mans and is barely even no­tice­able. As with many other snakes when cap­tured, they often re­lease musk and smear the cap­tor with cloa­cal mat­ter (Ama­ral 1999). Oc­ca­sion­ally they may even play dead by going com­pletely limp until they think the coast is clear (Wa­ter­molen 1991). A much more dra­matic dis­play of death-feign­ing has been recorded. The par­tic­u­lar snake wig­gled its tail, twitched the back of its body, rolled over ex­pos­ing the red belly, held its mouth open, pro­truded its tongue, con­torted its body, and then went com­pletely stiff in­stead of the usual limp dis­play (Jor­dan 1970). It is not known if this is ac­tu­ally a death-feign­ing dis­play or a stress in­duced seizure (Hard­ing 1997).

• Key Behaviors
• diurnal
• nocturnal
• motile
• migratory
• solitary

Com­mu­ni­ca­tion and Per­cep­tion

Red-bel­lied Snakes com­mu­ni­cate with each other pri­mar­ily through touch and smell, es­pe­cially dur­ing breed­ing. Out­side of the breed­ing sea­son they do not in­ter­act much with other snakes. They use their forked tongues to col­lect chem­i­cals from the air and in­sert these forks into a spe­cial organ in the roof of their mouth, which in­ter­prets these chem­i­cal sig­nals. Snakes are also sen­si­tive to vi­bra­tions and have rea­son­ably good vi­sion.

Food Habits

Red-bel­lied snakes are spe­cial­ized feed­ers of gas­tropods. Stom­ach con­tent analy­sis has re­vealed that at cer­tain times they may feed ex­clu­sively on slugs (Brown 1979, Sem­l­itsch and Moran 1984). Earth worms and snails are also very com­mon food items, while in­sect lar­vae and pill bugs, and pos­si­bly young sala­man­ders serve as food items (Hard­ing 1997).

They have a num­ber of adap­ta­tions to aid their spe­cial­ized gas­tro­pod diet. The teeth of S. oc­cip­it­o­mac­u­lata are es­pe­cially slen­der and in-curved so they can more eas­ily grasp and hold on to the slimy, soft bod­ies of slugs and snails (Ama­ral 1999). Their skulls are also pro­por­tion­ately smaller than other snakes, which may aid in ex­tract­ing snails from their shells (Ross­man and Myer 1999). It is pos­si­ble that they re­lease very weak venom from their Du­ver­noy glands dur­ing prey seizure. This venom may serve to both weaken the prey (re­duc­ing prey-han­dling time) and re­duce the ef­fects of the snail's mu­cous se­cre­tions (Ama­ral 1999).

• Primary Diet
• carnivore
  • eats non-insect arthropods

Pre­da­tion

Red-bel­lied snakes are eaten by a num­ber of preda­tors, in­clud­ing Amer­i­can crows, milk snakes, hawks, shrews, thir­teen-lined ground squir­rels, rac­coons, and do­mes­tic cats. They do not bite in re­sponse to a threat but will flat­ten their bod­ies and curl their upper 'lips' as a form of warn­ing. These snakes are very small, though, and their teeth wouldn't harm any but the tini­est of preda­tors. They can emit a foul-smelling sub­stance and smear it on their at­tacker if ha­rassed. Some will stiffen and roll onto their backs when ha­rassed, play­ing dead. This ex­poses their bright red belly and may be enough to star­tle a preda­tor mo­men­tar­ily and allow es­cape.

• Known Predators

  • American crows (Corvus brachyrhynchos)
  • milk snakes (Lampropeltis triangulum)
  • raccoons (Procyon lotor)
  • shrews (Soricidae)
  • hawks (Accipitridae)
  • thirteen-lined ground squirrels (Spermophilus tridecemlineatus)
  • domestic cats (Felis silvestris)

Ecosys­tem Roles

Red-bel­lied Snakes help to con­trol pop­u­la­tions of slugs, snails, and earth­worms. They are also a valu­able food source for the an­i­mals who prey on them.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Al­though seem­ingly in­signif­i­cant, red-bel­lied snakes may be im­por­tant to us in any num­ber of un­forseen ways. They are likely an im­por­tant link in the food web as both preda­tor and prey, and are there­fore im­por­tant in sus­tain­ing the in­tegrity of our nat­ural ecosys­tems. The con­di­tion of our ecosys­tems will likely, in time, be re­flected in our econ­omy.

In ad­di­tion to food web re­la­tion­ships, their con­sump­tion of slugs, snails, and oc­ca­sion­ally in­sects and lar­vae, may aid in con­trol­ling these pests in our farm­lands and gar­dens (Hard­ing 1997).

• Positive Impacts
• controls pest population

Con­ser­va­tion Sta­tus

Red-bel­lied snakes often turn up around lum­ber, sheet metal, and other de­bris around homes, aban­doned build­ings, and trash dumps. Their prox­im­ity to hu­mans can often re­sult in death by some fear­ful per­son.

Red-bel­lied snakes are, cur­rently, lo­cally com­mon in areas of suit­able habi­tat. How­ever, habi­tat frag­men­ta­tion is prob­a­bly re­duc­ing their num­bers to some de­gree. They are often killed in large num­bers while cross­ing road­ways dur­ing mi­gra­tions to and from their hi­ber­nac­ula. Peo­ple should be ed­u­cated on the harm­less­ness and value of this species (Hard­ing 1997).

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Matthew Gates (au­thor), Michi­gan State Uni­ver­sity, James Hard­ing (ed­i­tor), Michi­gan State Uni­ver­sity.

Ref­er­ences

Ama­ral, J. 1999. Lip-curl­ing in Red­belly Snakes (Store­ria oc­cip­it­o­mac­u­lata): Func­tional mor­phol­ogy and eco­log­i­cal sig­nif­i­cance. Jour­nal of Zo­ol­ogy, 248(3): 289-293.

Bar­ret, G., M. Vil­lar­roul. 1994. Store­ria oc­cip­it­o­mac­u­lata oc­cip­it­o­mac­u­lata (North­ern Red-bel­lied Snake). Pre­da­tion. Her­peto­log­i­cal Re­view, 25(1): 29-30.

Behler, J., F. King. 1979. Na­tional Audubon So­ci­ety Field Guide to North Amer­i­can Rep­tiles and Am­phib­ians. New York, NY: Chan­ti­cleer Press and Al­fred A. Knopf, Inc..

Blan­chard, F. 1937. Data on the nat­ural his­tory of the Red-bel­lied Snake, Store­ria oc­cip­it­o­mac­u­lata (Storer), in north­ern Michi­gan. Copeia, 1937: 151-162.

Brown, E. 1979. Stray food records from New York and Michi­gan snakes. Amer­i­can Mid­land Naturlaist, 102(1): 200-203.

Car­pen­ter, C. 1953. A study of hi­ber­nac­ula and hi­ber­nat­ing as­so­ci­a­tions of snakes and am­phib­ians in Michi­gan. Ecol­ogy, 34(1): 74-80.

Hard­ing, J. 1997. Am­phib­ians and Rep­tiles of the Great Lakes Re­gion. Ann Arbor, Michi­gan: Uni­ver­sity of Michi­gan Press.

Jor­dan, R. 1970. Death-feign­ing in a cap­tive Red-bel­lied Snake, Store­ria oc­cip­it­o­mac­u­lata (Storer). Her­peto­log­ica, 26: 466-468.

Knapik, P., J. Hodg­son. 1986. Life his­tory notes. Ser­pentes. Store­ria oc­cip­it­o­mac­u­lata (Red belly Snake). Her­peto­log­i­cal Re­view, 17(1): 22.

Oliver, J. 1955. The Nat­ural His­tory of North Amer­i­can Am­phib­ians and Rep­tiles. Prince­ton, New Jer­sey: D. Van Nos­trand Com­pany.

Ross­man, D., P. Myer. 1990. Be­hav­ioral and mor­pho­log­i­cal adap­ta­tions for snail exrac­tion in the North Amer­i­can Brown Snakes (Genus Store­ria). Jour­nal of Her­petol­ogy, 24(4): 434-438.

Sem­l­itsch, R., G. Moran. 1984. Ecol­ogy of the Red­belly Snake (Store­ria oc­cip­it­o­mac­u­lata) using mesic habi­tats in South Car­olina. Amer­i­can Mid­land Nat­u­ral­ist, 111(1): 33-40.

Smith, H., E. Brodie Jr.. 1982. A Guide to Field Iden­ti­fi­ca­tion: Rep­tiles of North Amer­ica. Racine, Wis­con­sin: West­ern Pub­lish­ing Com­pany.

Wa­ter­molen, D. 1991. Store­ria oc­cip­it­o­mac­u­lata oc­cip­it­o­mac­u­lata (North­ern Red-belly Snake). Be­hav­ior. Her­peto­log­i­cal Re­view, 22(2): 61.