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Eastern Racer - Coluber constrictor PDF Print E-mail
 A Field Guide to Amphibians and Reptiles of Iowa


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See the Minnesota HerpNet Site for more on the Racer  

 Synonyms: North American Racer, Eastern Yellow-bellied Racer.


PROTECTED. It is illegal to kill or collect this species by law in Iowa. Common throughout nearly all of Iowa, they are protected under state law.

Racer, blue racer snake, Coluber constrictor in Louisa County, Iowa
Adult Racer, from Louisa County, Iowa


The eastern racer is a large Iowa species measuring between 23 and 50 inches in length (Conant and Collins, 1991). Adults are uniformly blue, bluish black, greenish, or light brown. There are no head or dorsal markings. The undersurface is dirty white, porcelain, or yellow with no markings. The throat and neck are bright yellow and the chin and upper labials may be yellow or white.

Juvenile racer, venter. Van Buren County, Iowa
Juvenile Racer, Coluber constrictor, venter, from Van Buren County, Iowa

Juvenile racer, blue racer, black racer, blacksnake
Juvenile Racer, Coluber constrictor, from Van Buren County, Iowa

This is one of the few Iowa snakes that go through a remarkable ontogenetic color and pattern change. The young are vividly marked above and below having a white or gray ground color with black, brown, or reddish blotches. The belly is white with small brown or reddish spots.

Racer, blueracer, blackracer, snake, Muscatine county, Iowa
Adult Racer, Coluber constrictor, from Muscatine County, Iowa

Young eastern racers will be difficult to distinguish from other small spotted snakes. The most useful characteristic for a specimen in hand is the tail. Even newly hatched racers have an unmarked brown tail above and below; all other small spotted snakes have rings or bands on their tail almost to the tip. They lose these markings and develop adult coloration in one to two years. Eastern racers have smooth scales and divided anal plates.


Racer, snake, yellow bellied racer, western racer
Adult Racer, Coluber constrictor, from Woodbuy County, Iowa

The yellowbelly racer, Coluber constrictor flaviventris, is found in most of Iowa. Some still recognize the blue racer, C. c. foxii, and is supposedly found in eastern Iowa. Both subspecies intergrade where their ranges meet in Iowa. Even outside of this intergrade zone, I find specimens that could be either.

Black racer, blackracer, snake, blacksnake, Lee County, Iowa
Adult Racer, Coluber constrictor, from Lee County, Iowa

The yellowbelly subspecies is quite variable in coloration, and encompasses the characteristics of the blue form. I generally consider Iowa populations to be made up of a few color variations of the yellowbelly racer, C. c. flaviventris. In extreme southeastern Iowa large specimens are charcoal black.

Range map for Coluber constrictor in Iowa
County records for the Racer in Iowa


The eastern racer is found statewide in Iowa. Only parts of north central Iowa may not have eastern racer populations (Christiansen and Bailey, 1991).


Eastern racers prefer open prairie, woodland edge, and bluff prairies. They live in fields, grasslands, and railroad grades adjacent to these habitats.


Adult Racer, Coluber constrictor, head, from Louisa County, Iowa

Eastern racers are the quickest snakes in Iowa and also our most visually oriented. They are active hunters, moving quietly through grass and brush in search of food. They are diurnal even in hot weather. This thermoregulatory habit enhances their ability to chase down and capture fast moving prey. When they feel threatened, they can flee with incredible speed.

They seem to have good home range orientation as they will slither, often toward an intruder, and zip into a preferred hiding spot. Some people contend that eastern racers will chase them. I have not had this happen, but I have had them slither toward me, only to shoot down a burrow they seem to be familiar with.

Racer, (blue racer, black racer) young, Louisa County, Iowa
Racer, Coluber constrictor, young, from Louisa County, Iowa

Even if eastern racers were chasing someone, humans can run much faster than the fastest racer, and if they did strike, their bite is harmless and could not penetrate sturdy shoes, boots, or pants. When cornered, however, they may raise their head, strike, and vibrate their tails, (which is much slower; just rapid tail wagging when compared to faster vibrations in rat, bull, or fox snakes).

Generally, if they are picked up, they will musk, defecate, and bite by striking and chewing with their long teeth. However, I have seen some specimens curl up in a ball and hide their head in their coils. I have observed this behavior on hot and cool days alike. On cool rainy days, eastern racers may be found hiding under rocks, logs, boards, or in rocky crevices. They are active from April to October and hibernate below the frost line, often with other species of snakes such as garter snakes, milk snakes, bullsnakes, timber rattlesnakes, fox snakes, and other eastern racers.

Adult racer, venter (blue racer, black racer, Woodbury County, Iowa
Adult Racer, Coluber constrictor, venter, from Woodbury County, Iowa

They breed in spring, and the female lays 5-25 rather granular feeling eggs which hatch around late August.


This snake probably has the most diverse eating habits of any Iowa snake. They will eat about anything they can chase down. Food items include: rodents, insects, frogs, toads, lizards, snakes, reptile eggs, birds, and birds eggs. They are not constrictors, but they may use a loop or two of their coils to press victims to the ground. Large prey are shaken violently and rapidly chewed upon with the eastern racers strong jaws, while smaller food is simply swallowed alive. I have found the fecal matter of many wild eastern racers to be comprised largely of locust exoskeletons (LeClere, 1996). Many people have witnessed eastern racers chasing and consuming six-lined racerunners (not an easy task), and other snakes. On two occasions, young fox snakes were being consumed by eastern racers when they were discovered (Jessen, 1993; Bergquist, pers com.) and a large eastern garter snake on another (Lydon [Kaufman], pers com.). These events took place in Minnesota. Young eastern racers have been seen eating small brown and redbelly snakes (LeClere, pers obs.).






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