Effects of temperature and perch diameter on arboreal locomotion in the snake Elaphe guttata

Abstract

Arboreality is widespread in multiple lineages of snakes and these habitats are important for foraging, escaping predators, and thermoregulation for many species. However, very little is known about factors influencing the arboreal locomotor abilities of snakes. Arboreal performance was assessed in a semi-arboreal snake (Elaphe guttata) using an artificial perch apparatus. Locomotor velocity, body posture, and balance was measured during movement on three perch diameters (3, 6, 10-cm) at three temperatures (10, 20, 30 degrees C). Velocities attained by E. guttata on perches are much slower than those of terrestrial lateral undulation and swimming and somewhat slower than concertina velocities recorded in other species across the same experimental temperatures. At higher temperatures, faster speeds were associated with a more elongated posture. At lower temperatures, snakes displayed a more looped body posture, but still fell more often than at higher temperatures. Our results suggest that temperature has a large influence on both balance and movement by snakes on perches. Although there were no differences in velocities resulting from perch diameter, snakes fell more often from thicker perches. This differs from arboreal velocities attained by limbed vertebrates, which decrease with decreasing perch diameter, suggesting that snakes have a size-relative advantage over limbed animals, such as lizards, when traversing a network of narrow branches. Future studies investigating arboreal locomotion among snakes that vary both phylogenetically and morphologically are needed to assess the potential benefits of limblessness in complex, three-dimensional environments.

Perch size and structure have species-dependent effects on the arboreal locomotion of rat snakes and boa constrictors

“…By contrast, most studies of the arboreal locomotion of mammals have focused on kinematics, gait selection and dynamics (Lammers and Biknevicius, 2004;Schmitt, 1998;Schmitt et al, 2006). Hundreds of species of snakes from several phylogenetically distant lineages are arboreal (Lillywhite and Henderson, 1993;Pizzatto et al, 2007), but the effects of branch structure on kinematics, gait selection and locomotor performance are only well known for a single species of rat snake, Pantherophis guttatus (Astley and Jayne, 2007;Astley and Jayne, 2009;Gerald et al, 2008).…”

Arboreal habitat structure affects the performance and modes of locomotion of corn snakes (Elaphe guttata)

“…Many species and evolutionary lineages of snakes are arboreal (Lillywhite and Henderson, '93;Pizzatto et al, 2007), but the arboreal locomotion of snakes has barely been studied (Astley and Jayne, 2007;Gerald et al, 2008). The elongate and flexible bodies of snakes have several theoretical benefits for moving in arboreal habitats, such as distributing weight evenly across several thin branches, conforming easily to laterally restricted spaces, being able to form variable sizes of frictional grips on cylindrical surfaces, and placing their center of mass closer to the perch than the limbed organisms (Astley and Jayne, 2007).…”

Factors associated with nest survival of Black‐throated Sparrows, desert‐breeding nest‐site generalists

“…Snakes become more active and exhibit improved locomotor performance in arboreal environments as temperatures increase (Gerald et al. ). In our study area, maximum daily temperatures increase throughout the nesting period and range from an average of 25.1°C in April to 34.9°C in June (Western Regional Climate Center at http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?nmalam).…”

“…For example, Cox et al (2013) found that rates of nest predation by snakes increased with increasing temperatures, whereas rates of predation by mammals were virtually unchanged by an increase in temperature. Snakes become more active and exhibit improved locomotor performance in arboreal environments as temperatures increase (Gerald et al 2008). In our study area, maximum daily temperatures increase throughout the nesting period and range from an average of 25.1°C in April to 34.9°C in June (Western Regional Climate Center at http://www.wrcc.dri.edu/cgi-bin/cli MAIN.pl?nmalam).…”

“…We also included a nest random effect, allowing the model intercept to vary by nest. We chose specific covariates because each has been associated with nest survival in previous studies of songbirds (Martin and Roper 1988, G€ otmark et al 1995, Kozma and Mathews 1997, Noa et al 2007, Aldinger et al 2015. We centered and scaled all continuous covariates to have a mean of zero and a standard deviation of one: coverage, total shrubs, and nest height for the nest level and ordinal date for the visit level.…”