CIE Spotlight: Pasture height and crop direction influence reptile movement in an agricultural matrix

Don D.

Don D.

Authors: Kay, Geoffrey M.; Driscoll, Don A.; Lindenmayer, David B.; Pulsford, Stephanie A.; Mortelliti, Alessio

Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT, 235 164-171, NOV 1 2016

Brief summary of the paper: Tackling the global threat of habitat fragmentation on biodiversity requires knowledge of how species move within agricultural landscapes. However, the specific mechanisms influencing dispersal within such landscapes remain poorly understood.

The objective of our study was to assess how matrix type (improved pasture, native pasture or crop) and structure (grass height) influence fine-scale reptile movement, as well as influences of crop sowing direction and setting-sun position. In an agricultural region of south-eastern Australia, we first released 20 individuals of an arboreal gecko (Christinus marmoratus) at set distances from trees to determine the distance at which they could perceive their tree habitat (perceptual range).

We then translocated 36 individuals into six matrix environments within their perceptual range of isolated trees to examine how gecko movement was modified by the type and structure of the matrix. We also recorded crop sowing direction and setting-sun position and examined all recorded tracks using angular statistics.

We found that geckos exhibited a perceptual range of 40–80m. Short matrix environments promoted direct movements towards trees, irrespective of matrix type. Furthermore, movements were significantly affected by crop sowing direction with individuals following the planted lines.

Our study has three significant implications: (i) restoring mature tree spacing to 80 m apart will assist gecko movements, (ii) targeted management for low pasture height, such as by maintaining directional narrow strips of low vegetation among taller pastures, might assist movement and facilitate increased connectivity, (iii) directional sowing of crops between habitat patches presents a simple but potentially effective tool for reconnecting fragmented landscapes.