Texas A & M University Study Abroad: Dominica Dr. Robert Wharton Devra Hunter

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1 Texas A & M University Study Abroad: Dominica 2003 Dr. Robert Wharton Devra Hunter Anolis oculatus Habitat Selection By Samara Ferrara June 9, 2003 Springfield Station Roseau Syndicate Trail Emerald Pool Desolation Valley Ferrara 1/14

2 Abstract The Anolis oculatus or Tree Lizard, locally known as Zanndoli, is endemic to Dominica. The Anolis is approximately 9.8 cm SVL (snout vent length) and the tail is at least as long. For three weeks, I collected a total of 50 Anolis and recorded the sex, perch height and diameter, orientation of the body, SVL, tail length and hind limb length. I marked their hind limb with gold fingernail polish in order to avoid recording the same Anolis twice. My results confirmed my hypothesis, which stated that Anolis would prefer to be above the ground in a perch diameter smaller than or equal to 5 cm. Introduction Dominica is called the Island of Splendor for many reasons. It is a considerably small island (800 square kilometers) but has a great variety of amazing creatures. There are many species endemic to the island and one of them is the Tree Lizard or Anolis oculatus, locally known as Zanndoli. The Tree Lizard is the most widely distributed and most commonly encountered endemic species of wildlife on Dominica. The Tree Lizard is often abundant, particularly in dry forest, scrub and littoral woodland habitats (Evans & James 1997: 20). Lizards are diurnal (active during the day) and sedentary, occupying and defending their territory against any intruder. Most of these creatures will sleep in exactly the same place for their entire life span (Sutty 1993: 36). The Anolis varies in coloration according to its location among different habitats on the island. They vary from yellow (around Roseau) to dark green (Syndicate, Emerald Pool, Desolation Valley) to golden brown with numerous circular dots (Springfield Plantation) to grayish-cream (). Camouflage serves as a means of protection against predation. The adult males are bigger in size and more colored than the adult females and they have a yellow or orange throat fan or dewlap. The SVL can be up to 9.8 cm long (Anonymous: 45). In this three week long period I examined the Anolis habitat selection by looking at perch height. My hypothesis was that Anolis would prefer to be above the ground in a perch diameter smaller than or equal to 5 cm. Ferrara 2/14

3 Materials Headlamp Waterproof Pen Project Notebook Gold Fingernail Polish Ruler Methods The method I decided to use for my experiment was to look for Anolis on random days, particularly at night, when they are less active and easier to catch. I randomly observed and/or collected anoles at Springfield Plantation,, Roseau, Syndicate Trail, Emerald Pool and the Valley of Desolation. In my project notebook with my waterproof pen I recorded the perch height from the ground, the perch diameter or width and body orientation (up, down or straight). I measured the SVL, tail size and hind limb size with a ruler. Finally, I marked their hind limb with gold fingernail polish to determine which lizards had already been marked. I recorded the date and location where each particular anole was found. Results I collected a total of 50 Anolis and recorded the sex, perch height and diameter, orientation of the body, SVL, tail length and hind limb length. Discussion All of my data is recorded in Table 1. The first part of my experiment consisted of comparing the sex of the anole to the perch diameter. I found that over 50 percent of males and females select a perch diameter between 2 and 5 cm wide. The 10 cm perch size was the second most selected perch size for both males and females. Males selected perch diameters from 0 to 40cm wide (Table 2) but females were only found at perches Ferrara 3/14

4 from 0 to 10cm wide (Table 3). Graph 1 and 2 represent the numbers of males and females per perch diameter. The second part of the experiment involved comparing the size (SVL) of the Anolis to the perch diameter. Table 4 represents the number of Anolis at the different SVL (cm). A significant number of Anolis had a SVL of 5 cm. Refer to Graph 3 for the percentage of Anolis for each perch diameter for this group. Table 5 represents the total percent of Anolis at the different SVL (cm) vs. perch diameter (cm). I found no correlation between the size and perch use. The anoles with a SVL of 3.5 cm and 7.5 cm were both found on perches that are 5 cm wide. Between the different individuals with a SVL of 5 cm there were 61.1% using a 5 cm wide perch. For SVL values numbering 3.5, 5.5, 6.0 and 7.5 cm, the perch they selected the most was also 5 cm wide. I did not analyze the perch height, orientation of the body, tail or hind limb length, but the data are available for future use. If I had the opportunity to do my project in a different way I would try to catch more anoles using a noose, instead of by hand. I would also like to collect more anoles at each different location or habitat to see if there is any correlation between them. I would compare perch use vs. type of habitat or location. Conclusion My hypothesis was supported. Most Anolis selected a habitat above the ground in a perch diameter smaller than or equal to 5 cm. The majority of the males and females selected a perch of 5 cm wide as well as the majority of the anoles with a 5cm SVL. Acknowledgements I would like to thank Dr. Lee Fitzgerald and Dr. Robert Wharton for their help and support, knowledge and experience. I would also like to thank Celia Montes, Lauren Johnican, and Noelle Adams for assistance in catching and holding Anolis. Finally, I would like to thank Stephanie Zakel for revising my project and Rosanna Flores for helping me with the graphs. Ferrara 4/14

5 Works Cited Anonymous. Discover Dominica The Nature Island of the Caribbean. Warren Associates Publishing. Seventh Edition. Pg Evans, Peter G.H.: James Arlington Dominica: Nature Island of the Caribbean: Wildlife Checklists. Faygate Printing, Sussex, First Edition. Pg Sutty, Lesley Fauna of the Caribbean, The Last Survivors. Macmillan Press Ltd. Pg Ferrara 5/14

6 Table 1. Collected Data Date Anolis Sex Perch Perch Orienta- SVL Tail Hind Comments # Height Width tion (cm) (cm) limb 5/22 1 M 1m 20cm down Rock, Day, Springfield Pl. 5/22 2 M 0 0 down Hill, Day, 5/22 3 F 1.25m 5cm down Leaf, Night, 5/23 4 M 0.40m 5cm up Leaf, Night, 5/23 5 M 1.75m 5cm down Leaf, Night, 5/23 6 F 1.30m 5cm down Leaf, Night, 5/23 7 F 1m 5cm up Leaf, Night, 5/23 8 M 1.30m 5cm up Leaf, Night, 5/23 9 M 2m 5cm up Leaf, Night, 5/23 10 M 1.90m 5cm up Leaf, Night, 5/24 11 M 1.30m 2cm down Leaf, Night, 5/24 12 M 1.20m 3cm up Leaf, Night, 5/24 13 M 1.85m 20cm up Leaf, Night, Ferrara 6/14

7 5/24 14 M 1.95m 10cm up Leaf, Night, 5/24 15 M 2m 5cm up Leaf, Night, 5/24 16 M 2.10m 5cm up Leaf, Night, 5/24 17 M 2.15m 5cm up Leaf, Night, 5/24 18 F 0.60m 10cm up Leaf, Night, 5/26 19 M 1.50m 40cm up Trunk, Day, 5/26 20 M 1.50m 30cm up Trunk, Day, 5/26 21 F 2m 10cm up Trunk, Day 5/26 22 F 0.05m 5cm up Trunk, Day, 5/26 23 M 2.5m 5cm up Trunk,Day, 5/26 24 F 0 0cm straight Ground, Day, 5/26 25 M 1m 10cm down Trunk, Day, 5/26 26 M 1m 30cm down Trunk, Down, 5/26 27 M 1.50m 10cm down Trunk, Day, 5/26 28 M 0 0cm straight Ground, Day, Ferrara 7/14

8 5/26 29 M 2.20m 15cm up Trunk, Day, 5/28 30 M 1m 5cm up Leaf, Night, 5/28 31 M 1.5m 5cm up Leaf, Night, 5/28 32 M 2m 5cm up Leaf, Night, 5/28 33 M 0.45m 5cm up Leaf, Night, 5/28 34 M 0.30m 15cm down Leaf, Night, 5/28 35 M 2m 15cm up Leaf, Night, 5/28 36 F 1m 5cm up Leaf, Night, 5/31 37 M 0 0cm straight Ground, Day, Trafalgar F. 6/1 38 F 1m 10cm up Leaf, Night, 6/1 39 M 2m 5cm up Leaf, Night, 6/2 40 M 0 0cm straight Ground, Night, 6/4 41 F 1m 5cm up Leaf, Night, 6/4 42 M 1.50m 15cm up Leaf, Night, 6/4 43 M 1.50m 5cm up Leaf, Night, Ferrara 8/14

9 Ferrara 4 6/6 44 M 1.85m 10cm up Leaf, Night, 6/6 45 M 1m 5cm up Leaf, Night, 6/6 46 F 2m 5cm up Leaf, Night, 6/6 47 M 1.50m 5cm up Leaf, Night, 6/6 48 F cm up Leaf, Night, 6/6 49 M cm up Leaf, Night, 6/6 50 M cm up Leaf, Night, Ferrara 9/14

10 Table 2.Total Number and Percent of Males (out of 38) vs. Perch Diameters Perch Diameter # Males Percent (cm) or more Table 3.Total Number and Percent of Females (out of 12) vs. Perch Diameters Perch Diameter # Females Percent (cm) or more 0 0 Ferrara 10/14

11 Table 4. Total Number of Anolis vs. SVL (cm) SVL (cm) # of Anolis Ferrara 11/14

12 Table 5.Total Percent of Anolis at Various Perch Diameters (cm) According to SVL (cm) SVL values in cm. Perch Diamet er % % % % % % % % 0 100% % % % % % % 0 % % % % % 0 % % % % % % 0 0 Ferrara 12/14

13 Figure 1. Male # vs. Perch Diameter (cm) Males vs. Perch Diameter Perch Diameter (cm) Male # Males Figure 2. Female # vs. Perch Diameter (cm) Females vs. Perch Diameter Perch Diameter (cm) Female # Females Ferrara 13/14

14 Figure 3. Perch Diameter (cm) Percentages for Anolis of 5cm SVL. Percent for each Perch Diameter (cm) for Anolis of 5cm SVL Perch Diameters (cm) Ferrara 14/14