Thermal constraints of refuge use by Schreiber's green lizards, Lacerta schreiberi

Abstract

Prey should balance cost and benefits when deciding optimal refuge use. In ectotherms, such as lizards, body temperature can decrease in cold refuges, which has negative effects on physiological and locomotor performance. Thus, refuge use of ectotherms should be influenced by the thermal environment as well as by the body size-dependent thermal inertia of each individual. We simulated predator attacks to Schreiber's Green lizards (Lacerta schreiberi) and analyzed their refuge use. Results indicated that temperatures outside and inside a refuge had opposite effects on refuge use decisions. Thus, when initial external temperatures were higher and lizards had higher thermal inertia, lizards could spend longer times inside refuges before reaching a 'critical' low body temperature. However, when refuge temperature was low lizards did not decrease refuge use. If low refuge temperatures increased risk upon emerging because lizards had lower escape performance, lizards would need to compensate by remaining in a refuge for longer to scan the surroundings before emerging to ensure that the risk of a new attack decreased. Therefore, when deciding refuge use, L. schreiberi lizards seem to consider physiological costs of being at low temperatures and also the risk of emerging with low escape performance.

Sex- and performance-based escape behaviour in an Asian agamid lizard, Phrynocephalus vlangalii

“…Taking refuge leads to a loss of foraging time and carries thermal costs (Martin and Lopez 2000;Martin and Lopez 2003;Blumstein and Pelletier 2005;Martin and Lopez 2010), and as such, individuals are predicted to make decisions on refuge use based on their locomotor performance (Martin and Lopez 2010). In P. vlangalii, faster females were less likely to enter burrows when scared compared with slower females, whereas there did not appear to be a strong relationship between performance and refuge use in males.…”

“…With respect to locomotor performance capacity, we predicted that sprint speed would be inversely related to flight initiation distance, flight distance and refuge use because faster runners are predicted to be at a lower risk of predation and can more easily escape from predators (Irschick et al 2008). Similarly, we predicted that individuals with higher endurance would flee sooner (longer flight initiation distance), run longer distances and be less likely to seek refuge (Leal 1999;Le Galliard and Ferriere 2008;Martin and Lopez 2010).…”

“…For example, conspicuous individuals are predicted to flee earlier than cryptic ones if escape costs are low (Martin et al 2009). Additional measures of risk assessment during escape include flight distance and latency to enter a refuge (Martin and Lopez 2000;Lailvaux et al 2003;Martin and Lopez 2010). Locomotor performance capacity (sprint speed and endurance) is potentially a key driver of escape behaviour because of its obvious influence on evading capture by a predator.…”

“…For example, individuals with higher sprint speed are predicted to flee shorter distances (Lailvaux et al 2003;Broom and Ruxton 2005). Also, lizards such as Lacerta schreiberi adjust their refuge use based on sprint speed, with faster lizards decreasing their reliance on refuges (Martin and Lopez 2010). Because of differences and constraints in reproductive state (Schwarzkopf and Shine 1992;Olsson et al 2000;Cooper and Wilson 2007;Vanhooydonck et al 2007), escape behaviour is frequently sex-specific.…”

Escape strategy of Schreiber’s green lizards (Lacerta schreiberi) is determined by environment but not season or sex

“…Alternatively, differences might result from the above-mentioned detectability and predator attack success differences in different microhabitats. Also, thermal differences between exposed and refuge locations in different microhabitats, and their associated thermal costs, may be important (Martín & López, 1999b, 2010. Thus, in sunny exposed rocky microhabitats the substrate temperature can be very high whereas refuge temperature inside crevices is cold, while in microhabitats covered by vegetation, external and refuge temperatures are more balanced, which could result in a more predictable escape behaviour.…”