Chelonoidis denticulatus (Linnaeus, 1766)

Pereira-Ribeiro, Juliane, Ferreguetti, Atilla Colombo, Bergallo, Helena & Rocha, Carlos Frederico Duarte, 2024, Density, occupancy and detectability of tortoise species (Chelonoidis spp.) in the Atlantic Forest: implications for conservation and management, Journal of Natural History 58 (37 - 40), pp. 1529-1545 : 1535

Chelonoidis denticulatus

We recorded 35 individuals of C. denticulatus , 33 in active search during transects and two by occasional encounters. The records of occurrence of C. denticulatus were similarly distributed among the regions of the Reserve (west, north and south; Figure S1 ). Most individuals of C. denticulatus were recorded in the coastal plain forest (97.1%), at an average distance of 280 m from the nearest water resource.

We detected the species at 14 out of 24 sampling sites. The estimated population size of C. denticulatus for the entire reserve area was 153 individuals (153.27 ± 18.09). The estimated probability of occupancy was 66% (0.66 ± 0.12) and the estimated detection probability was 12% (0.12 ± 0.02).

The results of the model selection indicated that only the accumulated rainfall of the day before the sampling influenced the detectability of C. denticulatus , showing a positive relationship with the climate variable ( Figure 2 ). In addition, the best occupancy models contained the variables of distance from water and forest cover ( Table 1 ). The probability of C. denticulatus occupancy increased with increasing percentage of forest cover and decreased with increasing distance from water ( Figure 3 ). However, it is important to note that the difference in AIC values between the top model and the next best model, which excluded forest cover, was minimal. This slight difference suggests that the simpler model, with fewer parameters, could also be considered a strong candidate. While we selected the model including forest cover as the best model, both models provide valuable insights into the factors influencing the occupancy of C. denticulatus .

Figures

Figure 1. Location of the Vale Natural Reserve, municipality of Linhares, Espírito Santo, south-eastern Brazil, showing the location of the linear transects and the types of vegetation present in the Reserve.

Figure 2. Relationship between the probability of detection of Chelonoidis denticulatus (A) and Chelonoidis carbonarius (B) with the accumulated rainfall of the day before sampling (previous rainfall) in the Vale Natural Reserve, Brazil.

Figure 3. Relationship between the probability of occupancy of Chelonoidis denticulatus (A) and Chelonoidis carbonarius (B) with the distance from the water resource, and relationship between the probability of occupancy of Chelonoidis denticulatus and the percentage of forest cover (C) in the Vale Natural Reserve, Brazil.