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Bica Anole (Norops bicaorum)

Mohamed bin Zayed Species project number 172515600

Population Status and Conservation Requirements of the Bica Anole (Norops bicaorum)

Mohamed bin Zayed Species Conservation (Project No. 172515600) - Bica Anole - Awarded $6,000 on August 01, 2017

This project is performed in collaboration with Kanahau Utila Research & Conservation Facility (KURCF), based on Utila Island, Honduras.

 

Species description: The Bica Anole, Norops bicaorum Köhler, 1996 (alternatively Anolis bicaorum) is a poorly known species endemic to Isla de Utila, which is the westernmost of the three major Bay Islands and part of the Cayos Cochinos archipelago on the Caribbean side of Honduras in Central America. The species belongs to the Norops lemurinus species subgroup (Köhler and McCranie, 2001; Nicholson et al., 2012), along with its neighbouring island relative the Roatan Anole (Norops roatanensis). Despite being a charismatic and unique component of the herpetofauna on Isla de Utila, almost every aspect of N. bicaorum ecology was undocumented to any great detail prior to this study. Furthermore, observations suggest there are increasing threats to this species, including the presence of the notoriously invasive Cuban Brown Anole (Norops sagrei), and loss of the core broad-leaf and palm forest habitats N. bicaorum relies on. Consequently, the funding of this research comes at a critical time for the conservation of the Bica Anole, and indeed much of the islands unique reptiles.

Project aims: The focus of the research was to assess the abundance and distribution of N. bicaorum across the island, whilst dramatically increasing the knowledge surrounding the morphology, behaviour, ecology, habitat use and general natural history of the species. Our project involved researching in remote localities, often only accessible by boat and substantial financial, logistical and physical effort. The study incorporated numerous methodologies, including Visual Encounter Surveys along transects, Capture-Mark-Resight, Population Estimates and Opportunistic diurnal and nocturnal surveying, as well as various essential pieces of scientific equipment; all of which would not have been possible without MBZ funding. We aimed to create a morphometric database for the species, comprising many individuals across their range for comparison; whilst also collecting species and sex specific behavioural data within large populations, such as territory size, home range and mico-climate/habitat/perch use. It is with hope that our research will support a strong classification for the species on the IUCN Redlist in light of its restricted distribution and the threats to its population. Such a classification would aid the recognition of this unique anole, and substantially help its plight in being afforded active protection and further study. The behavioural and natural history component of the research will be used to actively inform any subsequent conservation management for N. bicaorum populations on the island, whilst being made freely available for use in a wider context in biology. The findings of our research have already contributed to the growing pool of species specific literature, collectively helping answer questions regarding anole ecology and behaviour.

Preliminary results

Natural History: Very little was previously published on the behaviour, diet or ecology of N. bicaorum, with all previous literature collated within McCranie & Kohler's book, ‘Anoles of Honduras (2015)'. As a preliminary result of this MBZ funded research, field notes and observations were published to update the literature and briefly record various aspects of unknown natural history in N. bicaorum, including descriptions of behaviour (territoriality, reproduction), habitat use, diurnal and nocturnal ecology (Brown et al. 2017 (1)), and the first records of sympatric occurrence and resource partitioning with its insular endemic N. utilensis (Brown et al. 2017 (2)). So far in the project, we have recorded >350 individuals of N. bicaorum; with 274 being located during timed VES surveys, totalling 143 male and 131 female observations. Of these observations, we captured and collected basic morphometric data for 104 males and 96 females, with their retrospective SVL averages and ranges being 65mm (53.2 - 74.6mm in males) and 62.2mm (52 - 70.7mm in females). McCranie & Kohler 2015 previously reported the SVL for the largest known female (86mm) and male (73mm) N. bicaorum, based on ten individuals of each sex. Additionally, female N. lemurinus from mainland Central America and from Utila's neighbouring island group Cayos Cochinos are reported to be equal to or greater in size than males (Savage 2002, Logan et al. 2012). The data we present juxtaposes these previous findings, increasing the maximum recorded size for male individuals, and contrasting the concept of female N. bicaorum being predominantly larger in SVL size. Our results on N. bicaorum morphology seemingly follow the pattern of many anole species, having male-biased sexual size dimorphism (Butler & Losos 2002, Losos 2009). Many of the individuals captured were marked following capture-mark-release methods and subsequently tracked to identify their home ranges and also population density, the data from such is still pending analysis. However, we can fore say that in some ca. 6000m2 plots we marked over 100 individuals across a five day survey period. The densest N. bicaorum populations were found within suitable patches of broad-leaf/palm forest on the eastern side, where on certain 100m transects, we encountered ca. 1 anole per every 5 meters. As the research is on-going, more publications will certainly arise in the near future in relation to abundance, population density, intersexual niche partitioning, home range and further descriptions of microclimate and habitat use.

Conservation: Previous investigation into Utila's anole populations found the N. bicaorum only within Lowland Moist Forest at elevations from sea level to 20m asl on the eastern portion of the island (Wilson and Townsend, 2006; McCranie and Köhler, 2015). Despite its restricted distribution, the conservation status of N. bicaorum has not been assessed by IUCN (www.redlist.org; accessed 15 April 2017); Johnson et al. (2015), however, calculated its EVS (Environmental Vulnerability Score) as 17, placing it in the middle portion of the high vulnerability category. More recent observations of N. bicaorum largely facilitated by the financial contribution made to this project by MBZ, suggests the species has a greater distribution encompassing the Northern, Southern and Western regions of the island, with its largest population densities occurring in appropriate hardwood and palm forest habitat on the eastern side upto an elevation of 74m asl (Brown et al. 2017 (1)). We also noted that a potentially major competitor and threat to the species includes the notoriously invasive anole, N. sagrei. Currently, this species only has only been observed in the streets, gardens, and vegetated patches throughout the Utila Town. To date, no N. sagrei individuals have been observed in Utila's broad-leaf forest habitats, which is fortunate because this species possibly could out-compete N. bicaorum. McCranie and Köhler (2015: 276) noted that N. bicaorum should be considered as Near Threatened in accordance to IUCN Redlist categories, and appears to be declining in altered habitat. Our preliminary results suggest this decline is almost certainly the result of disturbance and habitat change caused by the removal of forest habitats. The core forest habitat this species favours is severely limited and increasingly threatened. In the forest interior, N. bicaorum abundance contrasts with its relative absence in the surrounding agricultural, tropical savannah, mangrove and coastal habitats. We suggest indefinite development and continuation of such practices will eventually endanger N. bicaorum populations across the island. The best measures identified to ensure the immediate safety and longevity of the species would be to purchase an area of suitable broad-leaf/palm forest habitat and privately protect the land.

Continuation of study: At the time of writing this report, we are currently at the project halfway point, with the research at this stage providing more questions than answers. Consequently, as the project moves into 2018, we still have many aspects of anole ecology to investigate and formally document within this species. When the research is reinitiated in February 2018 by Kanahau (KURCF), we will continue to survey remote areas of the island in a bid to gain representative data across all localities. Additionally, revisits to sites which appeared to contain suitable habitat, but we did not locate anoles within, will be repeated to ensure accurate distribution results. Furthermore, we aim to continue collecting behavioural and morphological data via more capture-mark-release studies at different sites, with an updated focus on identifying sexual dimorphic behaviour and habitat use in this species. This study will also allow us to continue obtaining anole abundance and density estimates for various habitats types, identifying population hot-spots and investigating conservation measures. As previously mentioned, much of the collected data is pending analysis and publication. We hope in the near future (when combined with additional research), that this information can be released and made freely available. Once data analysis begins, we can also start to work alongside the Anole Specialist Group (ASG) and (IUCN), to begin officially classifying the species on the IUCN Redlist for threatened species; where we believe N. bicaorum could fall under the Near Threatened or Endangered category.

 

Project contributers

Tom W. Brown (Project leader) "There are too many people to thank who have contributed or offered their support to this research (so far), through assistance with field work, data collection/analysis, logistical support, reviewing annotations and providing expertise"; Diego Ardon, Sofia P. Irwin, Daisy F. Maryon, Emma Higgins, Cristina Arrivillaga, Andrea Martinez, Steve M. Clayson, Jonathon B. Losos. Additionally, a special thanks to Ellie Cline and all the volunteers that assisted with the 'Anole Patrol' research at Kanahau (KURCF) during 2016/17. Undoubtedly, as the research continues in 2018, there will be many more people to acknowledge in the future!

 

Research Permit details

All data collection was performed under valid biological research and collection permits (Resolución DE-MP-054-2017 – Dictamen técnico ICF-DVS-169-2017; Dictamen técnico DAP-068-2017); for the project “Conservación de los reptiles y anfibios de Utila, Honduras” issued to DFM and TWB of Kanahau (KURCF) by General Director Misael León and General Secretary Gudit Mariel Muñoz of Instituto Nacional de Conservación y Desarrollo Forestal, Áreas Protegidas y Vida Silvestre (ICF), Tegucicalpa, Honduras.

 

Literature & References

Brown, T. W., D, F. Maryon and G. L. Lonsdale. 2017 (2). Habitat diversification and natural history notes in Norops utilensis (Squamata: Dactyloidae) on Isla de Utila, Honduras. Mesoamerican Herpetology (in.press December 2017). 

https://www.researchgate.net/profile/Tom_Brown42/publications?pubType=article

Brown, T. W., D, F. Maryon, M. P. Van den Burg, and G. L. Lonsdale. 2017 (1). Distribution and natural history notes on Norops bicaorum (Squamata: Dactyloidae) endemic to Isla de Utila, Honduras. Mesoamerican Herpetology 4: 493-497. https://www.researchgate.net/publication/318085749_Distribution_and_natural_history_notes_on_Norops_bicaorum_Squamata_Dactyloidae_endemic_to_Isla_de_Utila_Honduras

Butler M, A. and Losos J. B. 2002. Multivariate sexual dimorphism, sexual selection, and adaptation in Greater Antillean Anolis lizards. Ecol Mon: vol. 72 (pg. 541-59)

Johnson, J. D., V. Mata-Silva, and L. D. Wilson. 2015. A conservation reassessment of the Central American herpetofauna based on the EVS measure. Amphibian & Reptile Conservation 9(2) [General Section] 1:94 (e100).

Köhler, G. 1996. Additions to the known herpetofauna of the Isla de Utila (Islas de la Bahia, Honduras) with description of a new species of the genus Norops (Reptilia: Iguanidae). Senckenbergiana Biologica 76: 19-28.

Köhler, G., and J. R. McCranie. 2001. Two new species of anoles from northern Honduras (Reptilia, Squamata, Polychrotidae). Senckenbergiana Biologica 81: 235-245.

Logan, M., C. Montgomery., S. Boback ., R. Reed., and Campbell J. 2012. Divergence in morphology, but not habitat use, despite low genetic differentiation among insular populations of the lizard Anolis lemurinus in Honduras. Journal of Tropical Ecology 28: 215-222

Losos, J. B. 2009. Lizards in an evolutionary tree. Berkeley & Los Angeles, CA: University of California Press.

McCranie, J. R., and G. Kohler. 2015. The Anoles (Reptilia: Squamata: Dactyloidae: Anolis: Norops) of Honduras: Systematics, Distribution, and Conservation. Bulletin of the Museum of Comparative Zoology, Special Publications Series, No. 1., Cambridge, Massachusetts, United States.

Nicholson, K. E., B. I. Crother, C. Guyer, and J. M. Savage. 2012. It is time for a new classification of anoles (Squamata: Dactyloidae). Zootaxa 3,477: 1-108.

Savage, J.M. (2002): The Amphibians and Reptiles of Costa Rica: A Herpetofauna between two Continents, between two Seas. University of Chicago Press, Chicago.

Project documents