B. c. nebulosus
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Natural History



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  Terry L. Vandeventer
1016 Andover Street
Clinton, Mississippi 39056



Abstract:          The snake species Boa constrictor occupies one of the largest ranges of any land serpent.  The reptile is deeply ingrained in the mind of the general public who frequently refers to any giant snake as a "boa constrictor." Considerable mention is made of B. constrictor in scientific literature but much of this is anecdotal or even fanciful.  The species has figured significantly in the pet trade for decades.  Still, the natural history of B. constrictor is virtually unknown and its taxonomic status poorly understood.  Observations on the natural history and incidental notes on captive husbandry are presented here. 

As might be expected with such a wide ranging species as Boa constrictor many geographical races, of subspecies, have been assigned over the years.  Several of these (constrictor, amarali, sabogae, imperator, occidentalis, nebulosus, orophias) are widely accepted, while others (melanogaster, ortonii, sigma, longicauda) are either considered invalid or highly questionable.  These races in question may, in fact, be genuine entities deserving of subspecific recognition, but either insufficient evidence or poor taxonomic methods render these names inappropriate at this time.

Boa constrictors from the Lesser Antilles have been known for many years.  Ditmars (1931) illustrated a "West Indian boa" and stated that it inhabited both St. Lucia and Dominica, and further elaborated that babies were sometimes inadvertently transported to neighboring islands with produce.  Stull (1935) referred to boas from both St. Lucia and Dominica as constrictor orophias. Upon examining the preserved head of a boa taken on Dominica by Samuel, Garman, James Lazell of the Harvard Museum of Comparative Zoology (where Garman was previously employed) felt that he saw differences which warranted some investigation.  Being familiar already with orophias from St. Lucia, Lazell decided to spend some time looking at boas on Dominica.  In 1964, he described Constrictor constrictor nebulosus from Woodford Hill, the Commonwealth of Dominica.  It was through my association with and the subsequent urging of James D. "Skip" Lazell that I decided to revisit Dominica 26 years later.

The island of Dominica is often confused with the Dominican Republic far to the north.  Pronounced "dom-in-EE-ka," this tiny island is only 29 miles long and 13 miles wide.  It lies in the Lesser Antilles north of Trinidad and the South American mainland.

Jutting out of gin-clear tropical waters, it is the tallest Caribbean island at almost 5000 feet on its highest volcanic peak.  It receives over 300 inches of rainfall yearly, producing lush rain forest over most of its area, thus the nickname, "the Emerald Island."

Dominica was discovered by Christopher Columbus on November 3, 1493.   He was impressed by its beauty but was unable to land on its rocky coastline.   As he passed by on a Sunday evening, he named it Dominica for the day of the week.   Although one of the poorest Caribbean nations, Dominica is rich in flora and fauna and leads many of its neighbors in its efforts to preserve its unique natural heritage.

In February of 1990, Robert A. Young, Tyler Miller, and the author spent eight days on Dominica observing and collecting herpetological specimens.   Special emphasis was placed on the endemic Dominican clouded boa, now known as Boa constrictor nebulosus.  During this time, we observed 15 adult nebulosus in the wild and examined another two very large females in a private zoo on the island.   At the end of this time, having painstakingly acquired the proper permits, five adult pairs were exported to the United States.  These specimens are housed in two facilities (TLV & RAY) and upon their deaths will be deposited at Harvard University and the University of Texas at Arlington.

Through the assistance of a local snake catcher who served as our guide, we were able to photograph, videotape, and capture the Tete’chein with some ease.  The name "Tete’chein" is French for “dog head" and is used on both Dominica and St. Lucia.  Nowhere did we hear any other names used, including "boa constrictor."

The Tete’chein has an unusual habit which it reportedly shares with the boas of St. Lucia whereas they tend to aggregate in small groups called a "cavalesche tete’chein" or loosely, a "snake tunnel." These dens were piles of rocks, a root system, or most frequently, a shallow undercut in a stream bank.  The site is in full sun but shaded by tall sedges and grass.  All were in the immediate vicinity of hot springs and sulfur gas vents along volcanic mountain streams. On a single occasion, we found a large, lone female, completely opaque in preparation to shed, basking in a patch of sunlight in the rain forest.  All others were found in groups.

Most days during our visit were mild, ranging from the mid 80s (Fahrenheit) during the day and dropping to the 60s at night.  Cool, moist ocean breezes made daytime activities quite pleasant, but cool nights limited our observations to the little geckos, Hemidactylus malbouia, which hung around the hotel hall lights.  Most mornings were rainy until about 11:00 a.m., at which time the sun warmed things up and scattered clouds prevailed for the remainder of the day.

After about an hour long drive along narrow mountain roads, we would meet our guide and continue on foot.  We hiked up beautiful creeks and rivers, always noting the large Anolis oculatus when we saw them. Of equal interest were the boiling springs and blowing gas vents along the way.  Near these blow-holes, the rocks and vegetation were covered with yellow sulfur deposits and we soon learned how to hunt snakes with our noses!  Here the boas set up their cavalesche.  During our forays, we discovered three such aggregations numbering 2, 5, and 7 adult snakes.   No offspring were observed on the trip.

These dens are very reliable and host snakes year round.  It is reasonable to think that mating occurs here but the true reason for gathering is not understood.  None of ours were in copula when they were discovered (boas often remain in copulation in excess of 48 hours) and the snakes remain here throughout the year.   Our guide hunts the tete’chien for "medicinal" oil and is very familiar with its habits.  He does not own a cage but simply visits his favorite cavalesche when he needs a snake, plucking out those that he wants and leaving the rest for a later date.

Within the cavalesche, we found the boas in close piles with heads resting on top.  The boas were hooked or pulled into the open where we could work with them more easily.  The snakes were quite hot to the touch as a result of coiling directly on the volcanically active soil.  Each defended itself in typical boa fashion, hissing, striking, and releasing musk. Oddly, these snakes soon calmed down and a few hours later in our hotel room, we were handling them as if they were old pets.

Although Dominica lacks the big lancehead pitvipers (bothrops) of nearby Martinique and St. Lucia, the people still fear their native tete’chien.   It is often killed on sight.  The Dominican Government discourages this practice and some individuals recognize the snakes' value as ratters, but old fears run deep.  Boas routinely take fowl, which certainly doesn't help its reputation with the impoverished country folk.  Like all Boa constrictors, nebulosus is sexually dimorphic in size, and additionally, color, and probably eye diameter.   Males average 4 to 5 1/2 feet long, while females went from 6 to 8 1/2 feet.   Males were slender and more distinctly patterned.  Females were lighter gray, and except for the tail, were nearly patternless anteriorly.  Very large, old females were virtually solid shiny black.  Since size dictates diet, it is reasonable to believe that it is most often large females which tend to raid the henhouse.  In the jungle, boas feed on birds, the native "manacou," or opossum (Didelphis m. insularis), and the introduced Rattus rattus. Juveniles may feed upon lizards, as well as small mammals.

The subspecific epithet nebulosus refers to the poorly defined or "nebulous" dorsal pattern of the race.  After the island was colonized by hurricane waifs from the mainland, natural selection produced the more somberly colored snakes we see here now.  Since this species is totally isolated from all other races and interbreeding does not occur anywhere, there exists a good case for elevating nebulosus (and orophias) to full species status.

After returning, fulfilling C.I.T.E.S and U.S. Fish & Wildlife obligations, and finally arriving home, we were pleased to see how well our new charges adapted to the captive state.  The first morning after our return, 8 of the 10 boas accepted dead rats as food.  By the next morning, the remainder had fed.   They were housed initially in two groups (2.2 and 3.3) in standard wood and glass snake cages.  Newspaper served as substrates and although hide boxes were provided, they were shunned.  The snakes preferred to coil in piles much like we had found in nature.  Each cage had a floor area of 2 x 6 feet.  At one end, the floor was heated from beneath by means of an electric heating pad.  Ambient temperature was maintained at 84 degrees fahrenheit and the snakes rarely utilized the hot spot provided.

All of the boas had ticks but none of them exhibited the "cauliflower" scarring on the heads and necks which ticks produce on B. c. constrictor from Guyana and Surinam.  It is thought that mainland boas soak in pools to alleviate ticks.  The ticks migrate to the snake's head and neck from under the water, forming concentrations (and perhaps infection) which produces the scarification.  Dominican clouded boas were not observed in pools, and ticks were located randomly over the dorsum.  Removal with forceps was effective.  Internal parasites included tapeworms, roundworms, protozoans, and pentastomes.  Metronidazole (250 mg/kg), Niclosamide (150 mg/kg), and Ivermectin (200 mcg/kg) was administered with good results.  Pentastomes were forcibly expelled from the lungs within 30 minutes of receiving Ivermectin I.M. injection.

During the latter part of March, breeding activity began among the boas.  This continued through most of April and four females exhibited distinct mid-body swelling.  As is typical for Boa constrictor, this lump lasted for 36 hours, then redistributed along the posterior half of the female.  Gestation lasted about four months with three litters (7, 9, and 11) in late July and August of 1990.  The neonates were average in size (approximately 17 inches) and were more vividly marked than the parents.  A fourth female dropped 13 infertile ova and one premature neonate in early July.  The baby did not survive.

The offspring from all three litters were initially difficult to feed. Offspring from other races are quite hearty by comparison but these young, born from different litters in two different facilities, steadfastly refused food.  All manner of fare was offered under a variety of conditions and ultimately most began feeding, seeming to prefer newborn rats while confined in a small container.  Three refused food, and although great efforts were extended by experienced curators, they succumbed.   Of the survivors, growth was rapid and unremarkable once feeding became regular.

Since the breeding of these naturally cycled wild captives took place in 1990, no new reproduction has occurred.  Standard techniques used to stimulate breeding in other subspecies (winter cooling, precipitation, photoperiod manipulation, etc.) has been ineffective.  One adult female has expired and was placed at U. T. A. All of the remaining 5.4 continue to thrive as of this presentation (6/92).


  Thanks is extended here to my fine friends Robert A. Young and Tyler Miller, who accompanied me to the Emerald Isle; to James D. Lazell , William W. Lamar, and Louis Porras, who assisted with permits and advice; and to Bob Sears and Terry Wilkins, who generously relayed their personal experiences on earlier trips to Dominica, thereby aiding in our success.


Booth, R., 1990.     Dominica. National Geographic. June: 100-120

Ditmars, R. 1931.   Snakes of the World. New York, Mamillan Co., 207pp

Lazell, J.D., 1964.  The Lesser Antillean representatives of  Bothrops and constrictor. Bull. Mus. Comp. Zool., Harvard U., Vol. 132, No. 3

Stull, O.G., 1935.  A check list of the family Boidae. Proc. Boston Soc.  Nat.  Hist., 40(8): 387-408

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