Habitat occupancy of endangered rhino horned lizard (Ceratophora stoddartii) in Horton plains national park, Sri Lanka

Abstract

AttachedHabitat occupancy o f endangered and endemic Rhino H om ed Lizard (Ceratophora stoddartii) was studied in the cloud forests, cloud forest die-back habitat, ecotone between forest and grasslands and grasslands o f the Hortain Plains National Park o f Sri Lanka from January 2015 to M ay 2015. C. stoddartii is easily distinguished from all other Ceratophora species by the presence o f a prominent rostral appendage, which is made up o f the rostral scale. The species is extremely slow m oving and is semi arboreal. Three 100 m transects were marked across each o f the four habitat types and the lizards were observed within a 3 m swath o f each transact. Each transect was surveyed three times a day and all lizards observed were hand captured, measured and sexed. 163 lizards were recorded during the survey. Significantly higher number o f lizards were observed in the Cloud forest die-back habitat (n = 97,59.5% o f the total) and the cloud forest habitat (n = 48,29.4% ). Low num ber o f lizards were recorded in the ecotone between forest and grassland (n = 18,11.0% ). N o lizards were recorded in the grasslands. The four habitat types differed significantly from one another in climatic and structural features. The occupied sites within the three habitats too varied significantly in all variables (p < 0.05). Both temperature (F3,i6 = 24.76, p < 0.05) and humidity (F3,i6 = 11.99, p < 0.05) had a significant effect on the probability o f lizard occurrence at a site. The temperature differed significantly among the four habitat types (p < 0.001) and relationship between the air tem perature and the C. stoddartii population density was negative (Pearson correlation, r = -0.5094, p < 0.05). There was a significant positive relationship between the relative hum idity and the mean C. stoddartii population density (Pearson correlation, r = 0.8164, p < 0.05). Lowest relative humidity was recorded from the grasslands (65.29 ± 7.69d %) and lizards were not observed). The leaf litter depth did not have any significant effect (p > 0.05) on the probability o f lizard occurrence in a site. The highest leaf litter depth was recorded within the Cloud Forest Die-back. The high amount o f leaf litter and optimum solar radiation at this site m ay have created a suitable environment towards the hatchability o f the C. stoddartii eggs as the juveniles showed a significant preference for locations w ith a higher amount o f leaf litter (x2 = 0.3758, p < 0.0001).