A Survey and Discussion of the Invasive Anolis

Erin McGrew

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A Survey and Discussion of the Invasive Anolis cristatellus and the

Endemic Anolis oculatus

Erin McGrew Study Abroad Dominica

May-June 2015 Dr. Lacher and Dr. Woolley

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Abstract

Anolis cristatellus is a nonnative species of anole inhabiting the island of Dominica. Its presence is worth observing because it poses a potential threat to the endemic Anolis oculatus. The purpose of this study is to survey the most recent range expansions of the invasive Anolis cristatellus and investigate if it is outcompeting the native Anolis oculatus. Data were collected using a survey method at various locations around the island. The invasion has expanded from its original contained area in Roseau, although it is maintained in human disturbed areas and has not extended into the heavily forested regions.

Introduction The Island of Dominica is often noted as possessing the most complete extant amphibian and reptile diversity out of all the Lesser Antilles (Malhotra et al., 2007). 21 species of reptiles and four species of amphibians inhabit the island of Dominica, five of which are endemic to the Lesser Antilles. (Alexander, 2007)

The Dominican Anole, Anolis oculatus, is an endemic lizard that is currently facing threats of extirpation from the invasive species, Puerto Rican Crested Anole Anolis cristatellus (Malhotra et al., 2011). A previous Texas A&M Dominica study completed five years ago showed the invasion to be contained to the Roseau/ Canefield area, for A. cristatellus was only observed at the Botanical Gardens in Roseau (Reinhart, 2010). Although the invasive Crested Anoles are present, the IUCN Red List currently classifies Anolis oculatus as a species of least concern (Hedges et al., 2013). The purpose of this study is to survey the most recent range expansions of the invasive Anolis cristatellus and investigate if it is outcompeting the native Anolis oculatus.

Experimental Design Data were collected using a survey method at various locations around the island. For each species found, the number of anoles and general habitat characteristics will be documented in a field notebook. Location coordinates and elevation will be determined using a Garmin 78 GPS unit. Google Earth will be used to map a general distribution of Anolis oculatus and Anolis cristatellus.

Locations for surveys will include trails originating at the Springfield Archbold Research and Education Centre, Roseau botanical gardens, and other national parks and tourist sites including Middleham Falls, Emerald Pool, Castle Bruce Beach, Cabrits National Park, Syndicate National Park, and Boeri Lake.

Finally, results will be compared to a previous Dominica study done in 2010. From the comparisons I hope to see if the invasive Anolis cristatellus is expanding its range on the island, for the 2010 study showed that A. cristatellus was contained in the Roseau/ Canefield area. I will determine if the invasive anole is out competing Anolis oculatus if only A. cristatellus is found in places where A. oculatus once was.

Results

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Out of the sites that I surveyed, Anolis cristatellus was observed at five of them (Figure 2): the Botanical Gardens in Roseau, Cabrits National Park, Castle Bruce Beach, Emerald Pool, and on the road to Middleham Falls. The Anolis cristatellus observed at Cabrits were limited to either open areas or the forest edge near the visitor entrance area. This includes the Fort Shirley building area. The Anolis cristatellus observed at Emerald Pool were limited to the visitor center building. All locations where A. cristatellus were found are disturbed human inhabited areas, and they did not extend past the forest edge habitat.

Anolis oculatus was observed at all locations except for the Botanical Gardens, Castle Bruce Beach, and on the road to Middleham Falls (Figure 1). The areas they were observed at include Cabrits National Park, the Checkhall River, Emerald Pool, Middleham Falls, Syndicate National Park, and the Springfield field station. Anolis oculatus mostly occurred within forested areas, but they were observed near human disturbed sites such as Springfield field station, the Syndicate visitor building, and the visitor’s building at Emerald Pool. Coordinates for Anolis oculatus and Anolis cristatellus observations are included in the appendix.

Table 1. Observations of individual A. oculatus and A. cristatellus. It should be

noted that these counts are from general surveys and not timed transects, so they do not represent population density.

Location Anolis oculatus Anolis cristatellus Botanical Gardens- Roseau 0 36 Cabrits 39 25 Castle Bruce Beach 0 1 Checkhall River 2 0 Emerald Pool 10 4 Middleham Falls 2 0 Road to Middleham falls 0 2 Springfield Field Station 2 0 Syndicate Nature Trail 2 0

Table 2. This chart shows locations of surveys, and what species was found there.

Numbers of specimens found cannot be used to indicate population size because there was not a formal standardize transect.

Location Anolis oculatus

Anolis cristatellus Habitat type

Botanical Gardens- Roseau Not Found Found Human Disturbed

Cabrts- Park Entrance/ Visitors Center Not Found Found

Human Disturbed

Cabrits- Forest/Park Entrance Edge Found Found Human Disturbed

Cabrits- Fort Shirley Found Found Human Disturbed

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Cabrits- Forest Trail Found Not Found Forested

Castle Bruce Beach Not Found Found Beach

Checkhall River Found Not Found Forested

Emerald Pool- Forest Found Not Found Forested

Emerald Pool- Visitors Center Found Found Human Disturbed

Middleham Falls- Forest Trail Found Not Found Forested

Road to Middleham falls Not Found Found Human Disturbed

Springfield field station Found Not Found Human Disturbed

Syndicate- Forest Trail Found Not Found Forested

Syndicate- Visitors Center Found Not Found Human Disturbed

Figure 1. Map of Anolis oculatus observations, represented by red circular icon.

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Figure 2. Map of Anolis cristatellus observations, represented by yellow circular icon.

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Figure 3. Map of Anolis oculatus and Anolis cristatellus observations. Anolis oculatus is represented by a red circular icon and Anolis cristatellus is represented by a yellow circular icon. Discussion

The results were compared to a Dominica study abroad project done by a Texas A&M student in 2010. The 2010 report indicated that Anolis cristatellus was found only in the Botanical Gardens in Roseau. The observance of the invasive anole at Cabrits, Castle Bruce, and Emerald pool suggest that the Puerto Rican Crested Anole has extended its range on the island.

Although Anolis oculatus does not seem to be decreasing its range, the data suggests that Anolis cristatellus is expanding its range. This expansion is limited to human disturbed habitat areas such as park buildings and their forested edge areas, where they observed in close contact with Anolis oculatus (Figure 3). Other types of habitat where the invasive anole was observed include telephone poles, rock piles next to houses, and a beach. It should be noted that Anolis cristatellus tend to exhibit more aggressive behavior than Anolis oculatus (Reinhart, 2010). This is could be a potential issue for the native species if the Anolis cristatellus spreads to the forested areas where Anolis oculatus is more prevalent. Future studies are warranted in order to ensure that Anolis oculatus is not decreasing in range.

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Conclusion

Anolis cristatellus was not observed within heavily forested areas, although the species was observed within the boundaries between forested and human impacted areas. Anolis oculatus does not appear to be drastically affected by the presence of the nonnative species. This issue should continue to be monitored because of the evident range expansion that has occurred within the last five years.

Acknowledgments I would like to thank the herp team, especially Sydney, Nick, and Brittany, for helping me in the rewarding, yet frustrating, capture of anoles. I would also like to thank Dr. Lacher and Dr. Woolley for this incredible experience and for going out of their way to help all of us students succeed in our research. Appendix

Anolis oculatus

Individual Coordinates Elevation General Location

AO1 N 15°20.930' W 061°20.395' 733m Middleham Falls

AO2 N 15°20.887' W 061°22.054' 399m Middleham Falls

AO3 N 15° 20.880' W 061° 22.055' 418m Mount Joy Trail

AO4 N 15°23.611' W 061°18.620' 490m Emerald Pool- Forest Trails





AO9 N 15° 23.841' W 061° 18.729' 419m Emerald Pool- Forest Trails




AO13 N 15° 23.739' W 061° 18.636' 421m Emerald Pool- Visitors Center

AO14 N 15° 35.001' W 061° 28.412' 56m Cabrits- Forest Edge



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AO20 N 15° 34.998' W 061° 28.410' 40m Cabrits- Fort Shirley

AO21 N 15° 35.077' W 061° 28.352' 63m Cabrits- Forested Trails
























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AO48 N 15° 31.465' W 061° 25.092' 621m Syndicate- Forested Trail

AO49 N 15° 31.435' W 061° 25.206' 588m Syndicate- Visitors Center

AO50 N 15° 20.812' W 061° 22.129' 292m Springfield Field Station

AO51 N 15° 20.805' W 061° 22.138' 335m Springfield Field Station

AO52 N 15° 34.947' W 061° 28.370' 28m Cabrits- Park Entrance/ Forest Edge




AO56 N 15° 35.025' W 061° 28.345 40m Cabrits- Fort Shirley


AO58 N 15° 20.723' W 061° 22.109' 317m Checkhall river

AO59 N 15° 20.727' W 061° 22.085' 353m Checkhall river

Anolis cristatellus Individual Coordinates Elevation General Location

AC1 N 15° 20.548' W 61° 21.685' 511m Road on Hike to Middleham Falls

AC2 N 15° 20.592' W 61° 21.353' 544m Road on Hike Middleham Falls

AC3 N 15° 23.721' W 61° 18.638' 395m Emerald Pool- Visitors Center




AC7 N 15° 34.950' W 61° 28.328' 19m Cabrits- Park Entrance/ Visitors Center




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AC28 N 15° 35.036' W 61° 28.385' 56m Cabrits- Fort Shirley

AC29 N 15° 17.924' W 61° 22.977' 37m Botanical Gardens










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AC55 N 15° 25.934' W 61° 15.319' 5m Castle Bruce Beach

AC56 N 15° 34.949' W 61° 28.369' 20m Cabrits- Forest/ Park Entrance Edge

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AC57 N 15° 34.980' W 61° 28.416' 62m Cabrits- Fort Shirley

AC58 N 15° 35.023' W 61° 28.342 353m Cabrits- Forest/ Park Entrance Edge

References Cited Hedges, S.B., Mayer, G.C. & Powell, R. 2013. Anolis oculatus. The IUCN Red List of

Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 29 March 2015.

Malhotra, A., Thorpe, R. S., Hypolite, E., & James, A. 2011. A report on the

status of the herpetofauna of the Commonwealth of Dominica, West Indies. Conservation of Caribbean Island Herpetofaunas, 2, 149-166.

Malhotra, A., Thorpe, R. S., Hypolite, E., & James, A. 2007. A report on

the status of the herpetofauna of the Commonwealth of Dominica, West Indies. Applied Herpetology, 4(2), 177-194.

Alexander, Kristen. A Photographic Field Guide to the Reptiles and Amphibians of Dominica, West Indies. Texas A&M University, Dominica Study Abroad 2007. Reinhart, Sammy. A Survey and Discussion of the Invasion of Anolis cristatellus and

its effects on the endemic Anolis oculatus. Texas A&M University, Dominica Study Abroad 2010.

Documents

A Survey and Discussion of the Invasive Anolis