Alsophis portoricensis anegadae (Squamata: Colubridae): Morphometric Characteristics, Activity Patterns, and Habitat Use
From 2001–2005, we collected and individually marked 219 Alsophis portoricensis anegadae from Guana Island, British Virgin Islands, during the months September–October to determine morphometric characters, evaluate incidence of scarring and tail damage, and assess habitat use and activity. Males were longer than females and significantly heavier and heavier per unit length. Sex ratio was almost exactly 1:1 (102 M:104 F). Undamaged tails of males were significantly longer than those of females, but rates of tail damage did not differ by sex. Scarring and tail damage were more abundant posteriorly on the body and tail, and were cumulative, occurring with significantly greater frequency in larger individuals. Most damage was probably attributable to unsuccessful predation attempts by Soldier Crabs (Coenobita clypeatus). We found snakes in all habitats except an open grassy plain. Activity appeared to be bimodal, with a depression during the heat of the day. Although usually diurnal, three snakes were observed active at night. Most snakes were on the ground, but a small number were in water or climbing on vegetation or human-made structures. Most were in full shade and very few in full sun when first observed. Snakes most frequently were sprawled, rarely coiled, and many were first seen while moving.Abstract

Sizes (SVL) of Alsophis portoricensis anegadae on Guana Island (n = 219).

The relationship between body length and mass in females (dots, full line) and males (triangles, dotted line) is significantly different.

Damage presumably inflicted by Soldier Crabs (Coenobita clypeatus) on Alsophis portoricensis from Guana Island, British Virgin Islands. (A) Damaged tail tip. The arrow indicates scarring just above the stump. (B) Recent damage to the posterior part of the body. The arrow indicates exposed bone. (C) Healed damage to tail. The arrows indicate two of three such scars on this individual.

Frequency of injuries as a function of size in Alsophis portoricensis. The number above each column represents sample size. (A) Tails are significantly more likely to be damaged as snakes grow larger. (B) The frequency of overall scarring increases with body size.

Activity time of Alsophis portoricensis on Guana Island, British Virgin Islands. Snakes are significantly more active during the morning and afternoon hours, when ambient temperatures are slightly cooler. (A) Effort controlled transect study (n = 20). The line shows ambient temperatures measured during the study. (B) Total observations over the five-year study period (n = 205).

Insolation conditions at locations where Alsophis portoricensis were observed on Guana Island, British Virgin Islands, as a function of activity time. Despite ongoing availability, snakes avoid direct sunlight during the warmest parts of the day.
Contributor Notes
(AB) Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37936; and (GP) Department of Natural Resource Management, Texas Tech University, Lubbock, Texas 79409; (RWH) Section of Vertebrate Zoology, Milwaukee Public Museum, Milwaukee, Wisconsin 53233-1478, and (RP) Department of Biology, Avila University, Kansas City, Missouri 64145, E-mail: (AB) abarun@utk.edu; (GP) gad.perry@ttu. edu; (RWH) rh@mpm.edu; (RP) robert. powell@avila.edu. Send reprint requests to GP.