Effects of habitat loss on tick load in central populations of the Eastern Green Lizard Lacerta viridis and its relationship with body condition and population density

Habitat loss can increase the susceptibility of individuals to parasitic infections, and hence, parasite load can serve as an early warning indicator of stress before the persistence of a population becomes threatened. In this study, we tested the effects of patch characteristics, isolation and landscape composition resulting from habitat loss on the tick load of individuals from central populations of the Eastern Green Lizard Lacerta viridis. We identified the spatial scale at which each landscape composition parameter has the strongest effect and evaluated its effects at this scale. Additionally, we tested the relationships between tick load and population density and body condition (BC) to understand possible mechanisms that determine tick loads in populations. We found that tick load was not affected by host population density. BC was not found to be affected by tick load, but BC did have a negative effect on lizards’ tick loads. The proportion of habitat and cropland in the landscape and patch size had positive effects on tick loads, whereas the proportion of urbanized areas, isolation and perimeter/area ratio had negative effects. We discuss our finding in the context of how the landscape can affect tick populations and other potential hosts. We conclude that tick load can be a suitable early warning indicator of negative effects of habitat loss, reflecting the susceptibility of lizards to infestation. We suggest that this indicator be included in monitoring programs aiming at evaluating the status of populations of L. viridis in modified landscapes, and recommend that conservation measures be focused on the protection of habitat at broader scales to compensate negative effects of cropland and urbanized areas occurring at small scales.