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Eastern Hognose Snake - Heterodon platirhinos 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 Eastern Hognose Snake  

Synonyms: Eastern Hog-nosed Snake.

Status

Hognose snake, Heterodon platyrhinos
Eastern Hognose Snake, Heterodon platyrhinos, neck spreading, from Van Buren County, Iowa
 

PROTECTED. It is illegal to kill or collect this species by law in Iowa. Although eastern hognose snakes are widely distributed in Iowa, they are relatively uncommon in most parts of the state.

Description

This is a medium to large Iowa snake that may be 24 to 46 inches long and has a very stout body. It is not considered venomous. They are rather variable in pattern and color; two phases may be found: spotted and solid. Spotted specimens have a brown or yellow ground color with darker brown or black blotches. These alternate with smaller dark spots on the sides. The blotches may turn into rings on the tail. There may be red or orange pigment in the skin between the scales, and this pigment may occasionally infringe upon the scales themselves. In some populations, adults are a solid color that may or may not have remnants of blotches. The ground color on solid individuals may be black, gray, or olive. Olive is the most common solid color phase in Iowa.

Heterodon platyrhinos, Eastern Hognose Snake
Eastern Hognose Snake, Heterodon platyrhinos, from Van Buren County, Iowa
 

The labial scales (lip scales) are light colored on all the variations. Regardless of dorsal coloration or pattern, the belly is yellow, gray, or pinkish, sometimes with gray or greenish mottling. The underside of the tail is always lighter colored than the belly. Eastern hognose snakes always have a dark longitudinal blotch behind each eye extending some distance onto the neck. These blotches are black in eastern hogs, not brown as in its cousin, the western hognose. The western hognose also has a light anal plate and the underside of the tail is black; the same color as the belly. The eastern hognose snakes underside of the tail is lighter than the belly. The rostral scale is enlarged, pointed, and keeled, just as in the western hognose, but it is not as upturned. The scales are keeled, and the anal plate is divided.

Subspecies

There are no recognized subspecies of the eastern hognose snake, Heterodon platirhinos (sometimes was spelled "platyrhinos").

Range

In Iowa, eastern hognose snakes are found statewide, except for the north central region.

 

County Records for the Eastern Hognose Snake in Iowa
County Records for the Eastern Hognose Snake in Iowa

Habitat

Eastern hognose snakes are not as choosy about their habitats as their western cousins. Heavily wooded areas, prairies, and grasslands are common habitats. They are even found on bluff prairies on occasion. Like western hognose snakes, however, these snakes prefer sandy or loamy soil in which to burrow. Eastern hognose snakes can be found with western hognoses where their ranges overlap in Iowa (Berberich, Dodge, and Folk, 1971; Christiansen, 1983). Easterns also adapt to many other habitat types than westerns and therefore are more widespread and common in Iowa. Eastern hognose snakes are found in more damp situations as they feed heavily upon amphibians. They are also found under flippable cover (as that afforded by rocky hillsides or logs) more often than the western hognose, although still rarely.

Eastern Hognose Snake, Heterodon platyrhinos
Eastern Hognose Snake, Heterodon platyrhinos, from Johnson County, Iowa
 

Habits

Heterodon platirhinos will fan its head and neck much like a cobra when alarmed. Loud and prolonged hissing is accompanied by short jabs with the head as often away from the attacker as toward it. The snake will not open its mouth to bite, and hognose snake bites originating from defense are rare. Even a large 43 inch specimen I found in Johnson County would not bite, but it acted as though it would.

If the attacker continues to press upon the hognose, it will open its mouth, writhe as if in pain and finally roll onto its back with its mouth open and tongue hanging out. It cannot be induced to move. Because the snake keeps its mouth open during the entire death scene, lining at the back of the mouth closes off the opening to the esophagus to prevent the swallowing of dirt. This is also aided by an increase in saliva production, which may run out of the mouth (readily seen when the snake is picked up), taking much of the dirt with it. If it is righted, it immediately rolls onto its back again. Not until the snake feels safe will it right itself and continue on with its normal activities. Eastern hognose snakes are more elaborate with their act than the western hognose, and even though they will perform the act in captivity for a longer period of time, they soon quit acting in captivity.

Eastern Hognose Snake, Heterodon platyrhinos playing dead
Eastern Hognose Snake, Heterodon platyrhinos, playing dead, from Van Buren County, Iowa

Eastern hognose snakes are diurnal and actively hunt for food. They may be observed basking in early morning and again at dusk. They are one of the few snakes that dig their own burrows, although they do not live in them for prolonged periods of time. Logs, rocks, boards, and other cover are used-especially just before shedding.

These snakes breed in the spring. They are oviparous and lay 10 - 30 eggs in a sandy area. The eggs hatch in about two months and the young are 5 - 12 inches at hatching. They are much brighter colored than the adults. H. platirhinos overwinter from October to late April in mammal or self constructed burrows.

Eastern Hognose Snake, Heterodon platyrhinos
Eastern Hognose Snake, Heterodon platyrhinos, head, from Van Buren County, Iowa

Food

Eastern hognose snakes consume amphibians, mainly toads, and use their snout to dig them up as toads spend much time in self made burrows. They also consume small mammals, birds, birds eggs (ground nesters), insects, lizards, snakes, reptile eggs, and carrion. They are immune to the toxic secretions that toads produce via the partoid glands. Eastern hognose snakes are not constrictors and swallow their prey alive.

Hognose snakes have enlarged rear maxillary teeth and some believe they may use this feature to deflate toads which may puff themselves up with air to unswallowable proportions. The teeth are more likely used to assist in the introduction of saliva into prey, however. I mentioned previously these snakes were nonvenomous, but there is some evidence that they may be mildly venomous (LeClere, 1996). Although there have been many cases of Heterodon envenomation, its toxicity is controversial. McAlister (1963) took extract from the salivary glands of H. platirhinos and injected white mice, spring peepers, Fowler's toads, and boreal chorus frogs in the thighs. The mice were unaffected.

Eastern Hognose Snake, Heterodon platyrhinos
Eastern Hognose Snake, Heterodon platyrhinos, head, from Muscatine County, Iowa

Fifteen of the seventeen amphibians died within two days. Subcutaneous hemorrhage, edema, and inflammation led McAlister to conclude that the venom is hemotoxic. Other authors have concurred that this genera of snakes is venomous; others discount it. Anderson tried several times to induce a H. platirhinos to envenomate him. He even made an extract and administered it to himself. It produced nothing more than slight burning.

 

More studies must be done to give a more concrete answer. Even so, it may be concluded that individual sensitivity plays the most important role in producing a malevolent affect. Bacteria cannot be discounted in these cases. With as many people that have had toxic symptoms from hognose snakes, there are many who have not. I have had a H. nasicus chew and embed one fang into my thumb without producing any ill effects, but I have a friend that did get a reaction from one. I have also experienced some of the swelling and itching described for some of the Heterodon accounts, to a lesser degree, from a "yellow" rat snake, and got a bad reaction from a bite from a Madagascar giant hognose snake, Leioheterodon modestus. This could possibly be individual sensitivity to a particular saliva. A study conducted on a greater number of humans and different species of amphibians, reptiles, and mammals may provide better answers.

 
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