Montana Field Guide

Milksnake - Lampropeltis triangulum

The back and sides of the body of the milk snake are marked with whitish, black, and reddish or orange bands, with the reddish-orange bands bordered by the black; the snout is blackish and sometimes with whitish flecking. The bands often extend across the belly, but sometimes may be incomplete or absent, in which case the belly is whitish. Dorsal scales are smooth (unkeeled). The anal scale is not divided, as are most of the scales on the ventral surface of the tail. The neck is relatively short and thick. Total length of adults in the western Great Plains is usually 39 to 85 centimeters. Hatchlings are similar in appearance to adults, and 16 to 29 centimeters in total length. Eggs are slightly granular and range from 29 to 44 millimeters x 13 to 16 millimeters in length and breadth, depending on locality.

The whitish, black, and reddish to orange banding or rings around the body, an undivided anal scale, and smooth (unkeeled) dorsal scales distinguish the milk snake from all other snakes native to Montana.

Montana Range

No information on the movement or migration of milk snakes is available for Montana. The species is believed to be non-migratory. Little information is available on movements of milk snakes throughout the species' range. They may migrate between hibernacula and summer ranges in some areas (Vogt 1981, Fitch and Fleet 1970, Hammerson 1999), and home ranges are about 20 hectares in northeastern Kansas.

Little specific information is available. Milk snakes have been reported in areas of open sagebrush-grassland habitat (Dood 1980) and ponderosa pine savannah with sandy soils (Hendricks 1999, B. Maxell personal communication, L. Vitt personal communication), most often in or near areas of rocky outcrops and hillsides or badland scarps, sometimes within city limits.

A carnivorous species, milk snakes eat mostly small vertebrates, including snakes, lizards (sagebrush lizard, prairie lizard, six-lined racerunner), reptile eggs, birds, bird eggs, small mammals (especially mice), and occasionally insects and worms (Hammerson 1999, St. John 2002, Stebbins 2003). The food habits in Montana have not been reported or studied.

Milk snakes are mostly crepuscular and nocturnal, although they may on occasion be active during the day, particularly during moist surface conditions. In Colorado, milk snakes emerge from dens in April and re-enter hibernacula in mid-October (Hammerson 1999), although they have been seen as late as mid-November. The active period in Montana is poorly documented; records extend from late May to October (B. Maxell personal communication). Predators are largely unknown, including in Montana, but milk snakes exhibit predator defense behavior, and rear up and strike, or vibrate the tail, when disturbed, although they are usually docile when handled.

No information specific to the reproductive habits of the milk snakes is known for Montana. Based upon information from other states, courtship and mating are believed to occur in spring, generally in May. Milk snakes lay clutches of 2 to 17 eggs; typical clutches in Colorado and adjacent areas are 4 to 6 eggs (Hammerson 1999). Eggs are laid usually in mid-June to mid-July. Eggs hatch in about 6 to 9 weeks, beginning in late August and most often in September. Some females reach sexual maturity in their 3rd or 4th year (45 to 50 centimeters snout-vent length) in Kansas (Fitch and Fleet 1970), and evidence indicates this is also the case in Colorado (Hammerson 1999). Longevity in wild populations is unreported, but captive individuals have lived more than 20 years.

So few recent milk snake records exist for Montana (Maxell et al. 2003) that it is difficult to determine if management activity is needed. Nevertheless, the widely scattered recent records indicate that milk snakes continue to occupy a large part of the known range in the state, and some sites near a large urban center have remained occupied for the last 40 to 45 years (L. Vitt personal communication). Management for this species is hampered by a lack of basic information on abundance, food habits, and habitat associations. No specific management activities are suggested at this time, other than to protect dens and regulate or restrict commercial harvest for the pet trade.