Post-emergent field activity and growth rates of hatchling spur-thighed tortoises,Testudo graeca

Abstract

Activity, mobility, growth rates, and space use of 48 hatchling spur-thighed tortoises, Testudo graeca, were monitored over a period of 8 months, from emergence from the nest in September until May. Individuals were followed by means of thread trailing and radio tracking. Overall average distance moved was 4.42 m/day and average home-range size was 13.7 m2. Hatchlings were active from emergence until mid-December, exhibited discontinuous hibernation until mid-February, and reached highest activity and mobility values in April–May. Overall, mobility varied significantly with daily solar radiation values and maximum temperature, and was significantly dependent on body condition in winter. Body size and mass had no influence on individual performance, and a significant proportion of variance among individuals remained unexplained. Little growth occurred in autumn and body condition decreased steadily, increasing only from February onwards. Growth rates increased in March–April. No individual differences in growth rates were detected, initial body size being the main determinant of body size after 8 months.

Differences in Reproductive Success in Young and Old Females of a Long-Lived Species

“…Overall survival from emergence to overwintering in this study was higher in hatchlings from old females (56% when extrapolating fortnight survival) than their counterparts in Southern Spain (39% [ 31 ]). In our study, raven predation is a plausible threat for the hatchling population, as occurred in other populations of Maamora forest [ 22 ] and in other Testudinidae populations, where it is known to cause high mortality [ 72 ]. However, the effect of traffic and trampling by large ungulates found in our study, and as occurred in northern populations of T. graeca [ 31 ], is a minor cause of mortality.…”

Mass/Length Residuals: Measures of Body Condition or Generators of Spurious Results?

“…Authors BSI † r Parameters Treefrog Murphy (1994) TFL chorus tenure (ϩ) § Tortoise Keller et al (1997) log SCL speed (ϩ) §, season § Lizard Bradshaw and De'ath (1991) log SVL 0.98 season §, weather § Lizard Dunlap and Mathies (1993) log SVL disease (Ϫ) § Adder Madsen and Shine (1993) SVL mass loss § Python log SVL reproductive threshold §, food supply (ϩ) § Python Madsen and Shine (1999) log SVL reproductive threshold §, clutch size (ϩ) §, egg size (ϩ) §, year § Chamaeleon Cuadrado (1998) log SVL 0.91 ‡ mate guarding Iguana Wikelski and Trillmich (1997) Notes: In each study, body mass was regressed on the body size indicator (BSI). Any transformations are listed, as are values of the correlation coefficient r given for the regression (also equal to OLS slope/RMA slope).The residuals were analyzed in relation to the parameters shown.…”

Annual variation in the body condition of a small, arid-zone tortoise, Homopus signatus signatus

“…body reserves, urinary bladder or gut contents, or reproductive state; see overview in Bonnet et al, 2001), body mass fluctuations help us understand the physiological responses of tortoises to arid habitats. Body condition indices are often expressed as body mass relative to a linear measure of body size, or as the residual of mass to body size (Bonnet et al, 2001;Hailey, 2000;Jackson, 1980;Keller et al, 1997;Schulte-Hostedde et al, 2005;Willemsen and Hailey, 2002). Yet, body mass scaled on a linear measure of body size (usually straight carapace length in tortoises) might have limited value (Jacobson et al, 1993), especially when comparing animals with different mass-to-length relationships.…”