by Eileen Underwood and Matt Smith
Originally Published in The Cold Blooded News, V24: 6, Jun, 1997.
The rosy boa, Lichanura trivirgata, is one of only two boas found in the United States. Because of their gentle disposition and moderate size rosy boas make excellent pets. The rosy boa is a small boa, ranging from 24 to 42 inches (61 to 107 cm.) and weighing about 125g. They can live for 18 years in captivity. They have small eyes with vertical pupils, small head scales, and males can be distinguished from females based on the presence of spurs. Most rosy boas have three dorsal stripes, varying from well-defined to poorly-defined, and can be quite variable in color depending on subspecies and locality of origin.
Prior to recent suggested rearrangements, there were four distinct subspecies recognized: the desert rosy boa (Lichanura trivirgata gracia), whose range includes southeast California and southwest Arizona; the coastal rosy boa (Lichanura trivirgata roseofusca), found along the southwest California coast; the Baja rosy boa (Lichanura trivirgata myriolepis), from Baja; and the Mexican rosy boa (Lichanura trivirgata trivirgata), found in western mainland Mexico, southwest Arizona, and Southern Baja. The reader is referred to the article by Merker and Merker (1995) for references describing current taxonomic arguments.
Rosy boas are usually nocturnal but are diurnal in early spring. They are primarily terrestrial but will also climb low shrubs. Their normal habitat consists of desert, arid scrub, brushland, rocky chaparral, and ravines, in places where moisture is available. They spend much of their time hiding under rocks. In nature, they eat small mammals, including pinkie cottontails, and birds. Rosy boas are calm snakes, seldom biting, but will coil into a ball with head in center if frightened.
Captive care of rosy boas is not difficult as long as care is taken to avoid excess moisture. They can be housed in 10-20 gallon aquaria with escape-proof screen lids. They need good ventilation. Sweater boxes also make suitable enclosures as long as they have numerous holes in sides for ventilation. Undertank heating is essential, especially for gravid females. Substrates which have been used successfully include: newsprint, course sand, dried pine, aspen and Care Fresh. Rosy boas will utilize low climbing branches and require a shelter or hide box. Excess humidity is not tolerated well by rosy boas, but they do need access to fresh water. A small water bowl can be placed in the cage occasionally, e.g., for two days every one to two weeks, or if continuous access is desired, a smaller container will keep down soaking and humidity buildup. If using sweater boxes, a small deli cup can be glued to the bottom to serve as anchor with a second deli cup inserted into the first. The inner cup is filled about half way with water and can be cleaned and refilled weekly.
As with all snakes, rosy boas do best when provided with a temperature gradient. Rosy boas do well with a nighttime low of 68°F (20°C), a daytime high 82°F (28°C), and an additional basking site of 85° to 90°F (30° to 32°C). 90°F is the absolute maximum this snake can tolerate. Access to undertank heat of 85°F is mandatory for gravid females. Brumation temperatures should be in the low to mid 50’s with brumation lasting from 6 to 10 weeks.
In captivity rosy boas will eat appropriately-sized mice (pinkie, fuzzy, small adults) or chicks. Adults will eat one to three small mice weekly. It is important not to overfeed rosy boas to avoid the health problems associated with obesity.
Rosy boas are live bearers. They mate early to late spring (depending on subspecies) and have a gestation period of approximately 4 months. It is mandatory to have 85°F (30°C) undertank heat for the female while gravid. Clutch sizes vary with subspecies, with desert rosy boas giving birth to 2-5 babies and coastal rosy boas producing 2-10 babies (ave. 5).
Behler, John L. and King, F. Wayne (1979) The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, New York. 719pp.
Cobourn, John (1995) Boas & Pythons and other friendly snakes. T.F.H. publications, Inc., Neptune City, NJ. 191pp.
Mehrtens, John M. (1987) Living Snakes of the World. Sterling Publishing Co., Inc. New York.
Merker, Gerold and Merker, Cindy (1995) The Allure of Rosy Boas. Reptiles 2(4): 48-63.
Ross, M.D., Richard and Marzec, Gerald (1990) The Reproductive Husbandry of Pythons and Boas. Institute for Herpetological Research, PO Box 2227, Stanford, CA 94305.
Walls, Jerry G. (1994) Boas, Rosy and Ground. T.F.H. publications, Inc., Neptune City, NJ. 64pp.