Population Ecology of European Tortoises: Review of Field Techniques

Abstract

Field techniques used in recent studies of the population ecology of European tortoises are discussed. An efficient marking system suitable for large sample sizes is described. The dual problems ofageing adults and sexing juveniles are highlighted. The relative merits of sampling techniques are dependent on habitat and population density. Mark-recapture techniques are most suitable when sampling is conducted within a grid system which enables results to be stratified, allowing for differential ease of location. However, grid sampling is only practical where tortoise densities are high. At low density sites, or for brief surveys, recording numbers observed per man hour along random paths is the most convenient method, but allowances must be made for differential observer skill. Existing sampling methods bias against finding inactive animals and where these form a large proportion of the population, sample size is strongly influenced by habitat type.

Morphometric Data of Testudo Hermanni in the Vlora Area

“…For each gathered individual morphometric measurements were performed and the data are cast in a standard form. Data collection methodologies are based on the published work by local and foreign authors [9]. Each individual was marked with a unique code by sawing a piece of tortoise shell.…”

Double egg‐deposition in the European pond turtle,emys orbicularis,from central Italy

“…Specimens were measured according to a standardised procedure (Zuffi & Gariboldi, 1995a) and marked with notches on the marginal scutes (Stubbs et al, 1984); graphite tags were attached. Oviductal eggs were recorded by palpation of the inguinal region; 20 females were also radiographed in 1996 (Zuffi et al, 1996).…”

Using digital images in the study of fluctuating asymmetry in the spur-thighed tortoise Testudo graeca

“…All tortoises were sexed, photographed, and measured. Moreover, all captured tortoises were marked with a small notch in one of marginal scutes and an identification number was written using a permanent marker, so that tortoises could be identified using solely the images (Stubbs et al, 1984). The digital images were obtained with a Nikon P100 10-MP with reduced optical aberrations, and the tortoises were maintained without inclination to any side.…”

“…The SCL measurements were obtained along the median suture of the plastron, from the anterior edge of the carapace to the exterior margin of the supracaudal scute. The CCL was obtained by measuring the curvature of the carapace at its median line from the anterior edge of the carapace to the tip of the supracaudal scute (Stubbs et al, 1984).…”