Abstract
The populations of the widespread European pond turtle and their numbers are decreasing in Hungary and other European countries. Knowledge of basking habits, along with other biological characteristics of the species, could be important to preserve the European pond turtle. The purpose of our research was to assess the seasonal and daily basking activity of the European pond turtle, and the effects of weather parameters on sun-basking, for which no prior data exist for Hungary. Our study was carried out in the area of a dammed valley pond system at Gödöllő (Hungary) over two years. The results showed that the seasonal peak of the turtles’ basking (the highest number of observed sun-basking turtles) was in the spring. When using a finer time scale (1.5-hour intervals), we found that daily activity peaks were earlier in the spring and summer (11:00–12:30 h) than in autumn (12:30–14:00 h). Based on three measured temperatures (air temperature in shade and sunlight, water temperature), the number of basking turtles positively correlated with temperatures and varied seasonally; the optimal temperature ranges also shifted during the year. In the spring and autumn, turtles started sun-basking at lower temperatures than in the summer. We observed the narrowest optimal temperature ranges in the summer as well. Based on a Principal Component Analysis of weather parameters, low humidity and high air temperature created optimal basking conditions, whereas high humidity, and low air and water temperatures had an adverse effect.
Highlights
The importance of sun-basking is demonstrated by the distribution of freshwater turtles within potential habitats, which is primarily defined by their microhabitat parameters and the presence of optimal basking sites (Luiselli 2008)
The European pond turtle Emys orbicularis is a widespread species (Fritz 2003), but some European and Hungarian populations have shown a considerable decline in recent decades (Farkas and Sasvári 1999; Fritz and Chiari 2013)
The summarised data were analysed for the effect of year, season, the part of the day and the finer time scale period on the turtle basking activity patterns
Summary
In turtles (like in other reptiles and amphibians) maintaining proper body temperature by sun-basking influences multiple characteristics such as growth and development, intensity of metabolism, movement, nutritional and reproductive activity, behaviour, the possibility to colonize new habitats and successful defence against predators (Vitt and Caldwell 2014).The importance of sun-basking is demonstrated by the distribution of freshwater turtles within potential habitats, which is primarily defined by their microhabitat parameters and the presence of optimal basking sites (Luiselli 2008).The European pond turtle Emys orbicularis is a widespread species (Fritz 2003), but some European and Hungarian populations have shown a considerable decline in recent decades (Farkas and Sasvári 1999; Fritz and Chiari 2013). In turtles (like in other reptiles and amphibians) maintaining proper body temperature by sun-basking influences multiple characteristics such as growth and development, intensity of metabolism, movement, nutritional and reproductive activity, behaviour, the possibility to colonize new habitats and successful defence against predators (Vitt and Caldwell 2014). Biological characteristics of the species, including basking activity, require extensive research to provide the information to apply proper conservation measures. The European pond turtle utilises both aquatic and terrestrial habitats, but is essentially aquatic (Lanza 1983; Ficetola et al 2004). It leaves the water only for basking, egg laying, or migrating to new water bodies.
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