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Villas, villagers and tortoises in Greece—a sequel
Abstract
Despite protection of the species under the Berne Convention, and of the site by planning restrictions, Hermann's tortoises have again been killed at Alyki, 10 years after the original catastrophe. The authors describe the situation leading up to the recent habitat destruction, and its effect. There is a final opportunity to save the tortoise population before it is destroyed by holiday developments.
... (4) Coastal heath (150 ha), with mainly sandy substrate and characterised as 'heath'--due to its physiography rather than taxonomic composition-and described in detail by Stubbs et al. (1981aStubbs et al. ( , 1985. Both vegetative composition and physiography of this zone are changing rapidly due to human pressure through fires and construction (Hailey & Goutner, 1991). ...
... Despite such efforts, which started in 1980, and due to the indifference of the Greek State, a great part of the surrounding heath was burned and ploughed by local people for holiday housing development in 1980 and again in 1989. A more detailed description of the facts and their consequences on the herpetofauna is given in Stubbs (1981a,b), Stubbs et al. (1981aStubbs et al. ( ,b, 1985 and Hailey and Goutner (1991). The development sought by local people would destroy all the surrounding heath and the south part of the lagoon, which administratively belongs to the Community of Kitros. ...
The ornithological importance of the Alyki Kitrous wetland (Macedonia, Greece) is evaluated for five groups of birds of special conservation interest by comparison with existing criteria. Ten raptor species (six protected in the EC) occurred but in small numbers. Herons also occurred in small numbers, but wintering great white egrets Egretta alba and wintering and summering spoon-bills Platalea leucorodia occurred in numbers of international importance. Waterfowl were especially abundant in winter, but Alyki was of international importance only for shelduck Tadorna tadorna, although in the past it had also been important for Eurasian wigeons Anas penelope. Alyki was also nationally important for the most abundant wintering anatid species, and for overall numbers, and has been occasionally important for coots. Waders were most abundant in spring migration: avocets Recurvirostra avosetta (during most of the year) and collared-pratincoles Glareola pratincola (in summer) occurred in internationally important numbers. Of breeding waders the same species were important in numbers both internationally and nationally. The latter category also included black-winged stilts Himantopus himantopus. Larids formed one of the most abundant groups, and Alyki was internationally important for particular breeding species such as Mediterranean gulls Larus melanocephalus and gull-billed terns Gelochelidon nilotica. It was also nationally important for breeding common Sterna hirundo and little S. albifrons terns and wintering and breeding slender-billed gulls Larus genei. The Alyki Kitrous wetland is threatened by illegal building and unscheduled development of the salines in the area. Priority conservation measures are proposed.
... 1986, May 1988, and April 1989. There was a second major habitat destruction from November 1989 (Hailey and Goutner, 1991). Two intensive samples were made in 1990 to assess the impact of this, in April (sample 1990a) and June (sample 1990b), since mark-recapture methods do not give an estimate for the last sample in an analysis. ...
... Survival in sector 10 was also examined using the model 3.2.5. The 1989/90 ®re and habitat destruction Most of the main heath (Fig. 7a) and the whole of the southern heath was burnt in November 1989, followed by mechanical habitat destruction in the ®rst quarter of 1990 (Hailey and Goutner, 1991). Building plots of 20Â25 m were marked out in a regular grid around a major new vehicle track cleared through the centre ofTable 6 Analysis of the eect of the 1986 ®re (sectors 3 and 4) and the 1988 ®re (sector 10) on the population size (N) and survival rate (S) of sexable tortoises The area of major mechanical habitat destruction in winter 1989/90 (dense shading) around a new vehicle track, and the area of less intense mechanical habitat destruction (sparse shading). ...
The impact of fire and mechanical habitat destruction on a population of the tortoise Testudo hermanni in northern Greece varied with vegetation type and season. A major fire in summer 1980 caused low (10 cm) in coastal heath, highest (about 50%) mortality in grassland, and intermediate levels in dry heath. Mechanical habitat destruction caused about 50% mortality in affected areas. Mortality of juveniles was greater than that of sexable animals. Overall, the 1980 catastrophe was more damaging than previously thought, causing a 64% decrease in the total size of the Alyki main heath population. A localized summer fire in 1986 caused a similar level and pattern of mortality to that of 1980, but a spring fire in 1988 had little effect on the tortoise population. A fire and mechanical habitat destruction in winter 1989/90 caused only a 14% decrease in population size; mortality was again concentrated in grassland areas, but affected juveniles and sexable animals equally. Variation of mortality with season suggests that any burning needed for habitat management at tortoise sites should occur in winter or early spring. Juveniles were undersampled by 3–4 times compared to sexable animals; their number increased greatly by 1990, reaching the same proportion as in the original population. There was, however, no recovery in the number of sexable tortoises in the decade after the 1980 catastrophe.
... Altitude 0 m. Alyki main heath ± coastal heath, grassland and dry heath (Stubbs et al., 1985), which was burned and ploughed in 1980 and 1990 (Hailey & Goutner, 1991). Altitude 0 m. ...
Seventeen populations of T. hermanni in Greece differed substantially in mean adult body size, over a range of about one and a half times in length and three times in mass. Females were the larger sex in all populations; the degree of sexual size dimorphism did not vary with mean body size. The proximate cause of the variation of body size among populations was differences in the duration of growth, rather than egg or hatchling size or the growth rates of juveniles. The age at maturity (α) increased with body size in the 17 populations, while the Bertalanffy growth constant (k) decreased with body size. The quantities αM and M/k (where M is the instantaneous mortality rate) were invariant with body size, suggesting that differences between populations were adaptive rather than the result of short-term disturbance. Body size was greater in cooler areas, and increased with both latitude and altitude. This pattern is opposite to that found in most ectotherms (the reverse Bergmann's rule), and to that which occurs between tortoise species. Several hypotheses about the possible ultimate causes of variation of body size were rejected, including adaptation to long-term habitat disturbance (land use), character displacement, social factors, energetics, thermoregulation, r-K selection, the length of the season available for incubation, or differences in juvenile mortality. The most likely ultimate cause of size variation between sites is differences in adult mortality, the correlation with environmental temperature being through the frequency of fires.
... 1. The largest area was termed the main heath, which was burned and ploughed (Stubbs, Swingland et al., 1985 Hailey & Goutner, 1991). A second area, termed the salt works heath, had similar habitats and was separated from the main heath by the entrance to the saltwater lagoon. ...
The idea that the size of animal populations may be regulated by factors intrinsic to them, such as behaviour, has a long history in ecology. Although this idea is now rejected as a general mechanism, it may apply in some species where females are damaged during courtship attempts, such as the Mediterranean tortoise Testudo hermanni. The sex ratios (adult males: adult females) of most dense Greek populations were more extreme (over 1.5:1) than could be accounted for by the earlier age at maturity of males, and some ranged to over 6:1. The sex ratio was correlated with the population density of adult males and the frequency of courtship attempts on females, and negatively correlated with the longevity of females. A high population density of males limits the density of adult females. This intrinsic regulation of population size is a consequence, rather than a goal, of a particular type of courtship behaviour (persistent thrusts by the male using a tail with a sharp terminal spur) in T. hermanni. Existing population densities at many Greek sites are probably unnaturally high, owing to the reduction of natural predators.
... The coastal heathland surrounding the lagoon at Alyki supported a diverse herpetofauna (Willemsen and Hailey 1989 ) including a large population of Hermann's tortoise , Testudo hermanni. However, the population of about 5000 tortoises on the main heath was reduced by 64% by an intense summer fire and subsequent mechanical habitat destruction in 1980, with further damage in winter 1989/1990 leading to an additional 14% reduction ( Hailey and Goutner 1991; Hailey 2000a). The recovery of the population from these disturbances is of particular interest for the conservation biology of chelonians, which are characterised by late maturity and long generation times (Gibbons 1987; Condgon et al. 1993). ...
The Alyki wetland in northern Greece is a site of notable herpetological and ornithological importance. A large population of the tortoise Testudo hermanni began to recover slowly (r = 0.016) between 1990 and 1999, following catastrophic habitat destruction in 1980 and slow decline from 1980–1990. Heathland vegetation showed signs of desiccation, probably due to increased drainage by the salt works, including deterioration of Crataegus, Ruscus and Asphodelus, and loss of formerly important food plants of tortoises. Activity and body mass condition of tortoises were reduced in summer in grassy heath habitats. Predation of artificial (chicken egg) tortoise nests increased, and the relative frequency of juveniles (about 1 % of samples) was lower than after severe habitat destruction or pesticide damage. These changes were attributed to an increasing population of badgers, Meles meles. Population levels of waders were lower in 1998/1999 than in 1988/1989, especially avocets (Recurvirostra avosetta) for which the site was internationally important. Breeding populations of most waders and larids also declined. Mediterranean gulls, for which Alyki was formerly the most important breeding area outside Russia, did not nest from 1990 to 1998, and nests were unsuccessful in 1999. Changes in breeding populations were due to falling lagoon levels, exposure to predators and vegetation encroachment on islet breeding sites. Midwinter waterfowl populations remained high or increased, however, as alternative feeding areas were available in the lagoon. Preservation of the habitats against development of the salt works and increasing desiccation are necessary to maintain the long-term conservation value of the Alyki site.
The Mediterranean tortoise (Testudo graeca) is listed as "Vulnerable" on the IUCN Red List. Reproductive characteristics and means to increase offspring production were studied in T. graeca terrestris in a semi-natural environment. Courtship and mating occurred during early spring for about 4 weeks, followed by a laying season of approximately 2 months, with a second, shorter mating period in the fall. During the first mating, calcified eggs were already present in the uterus; we inferred that sperm from both mating seasons were stored in the oviduct for fertilization of eggs of the second laying cycle and of the following year. Average egg production was 3.8+/-0.3 eggs/year. Most females laid all of their eggs in a single clutch, but 18% laid in a second clutch, 11-21 days later. X-ray radiography revealed calcified eggs in the uterus about 4 weeks before oviposition. All eggs in the uterus were calcified simultaneously and were laid in a single clutch; if a second clutch developed, those eggs were also calcified simultaneously. Based on endoscopic examinations, ovaries were active throughout the entire year. Plasma progesterone concentrations in females were very low and were detected only soon after oviposition ( 440 +/-141 pg/ml). Plasma estradiol concentrations in females varied from 4.1 +/-1.5 pg/ml to 70.2 +/-29.4 pg/ml, with no clear seasonal pattern. Maintaining tortoises at a low environmental temperature (9 +/-1 degrees C versus 28 +/- 1 degrees C) reduced plasma estradiol concentrations. Giving 2mg/kg tamoxifen (TAM) increased plasma estradiol to 220 +/-33 pg/ml when treatment was given in September but not in late October, winter or spring. Treatment with TAM increased the number of eggs laid during the following laying season to 7.3 +/- 1.0 eggs/year, laid in one to three clutches. In males, plasma testosterone concentrations had a seasonal pattern with the onset of a rise in July from 2 to >4ng/ml, a continued increase to a peak of 12.8+/-5.3 ng/ml during November and a decline thereafter. Artificial incubation in sand at 29 +/-1 degrees C shortened the natural incubation time of 103+/-3.1 days to 83.5 +/- 1.3 days, increased hatching rate from 28 to 53%, and increased survival rate from 51 to 71% at 40 weeks of age. In summary, this study provides options for increasing reproductive performance, hatchability and offspring survival in captive Mediterranean tortoises, and may offer new tools for conservation of animals that are on the verge of extinction.
Survival, recruitment and dynamics of adult Testudo hermanni at Alyki (N Greece) were studied from 1980-1988. Recruitment of adult males was greater than that of females owing to their shorter time to maturity (9 vs. 11 yr); recruitment of subadults (6 yr old) was equal in males and females. Mean annual survival was slightly greater in males (0.914) than females (0.877), equivalent to mean adult longevity values of 11.6 and 8.1 yr, respectively. Excluding tortoises that die before maturity, male and female T. hermanni are mature for c56 and 42% of their life, respectively. Generation time was roughly twice the age at maturity, and 3 times the age at which secondary sexual characters develop. The combination of adult survival and recruitment should lead to a stable sex ratio (males/females) of 2.1. The adult sex ratio was higher than this, but decreasing, from 4.1 in 1982 to 3.0 in 1986, with an increase in the female population; number of males was stable. The observed sex ratio showed a similar decline and a further fall to 2.4 in 1988. The cause of the lower survival rate of females compared with males is proposed to be damage during courtship attempts. -from Author
Two large, dense and viable populations of Testudo hermanni inhabiting adjacent sites in northern Greece were studied over three years. One site experienced severe habitat destruction by fire during the course of the study, and the other may either have been seriously disturbed in a single event several years previously, or is suffering from a continual low level of disturbance. In the stable situation average population density was estimated as 45 tortoises ha −1 and in parts may have reached 100 ha−1 The adult sex ratio was biased 2:1 in favour of males, due to higher female mortality. Most animals were sedentary, but there were some seasonal movements between vegetation types for feeding. The immediate effect of the fire was an estimated 40% population reduction, with juveniles being most severely affected. Subsequently the growth rate of immature animals rose sharply. This study demonstrates the relative resistance of tortoise populations to a sudden and temporary catastrophe, and their high potential for recovery if left undisturbed.
In the summer of 1980 four members of the University of London Natural History Society went to Lake Alyki in Macedonia to study a population of tortoises Testudo hermanni. Such studies are urgently needed because very little is known about the ecology of Mediterranean tortoises, which are declining seriously, due mainly to habitat loss and collecting for the pet trade. The expedition chose Alyki after an expedition by the same society in 1979 had reported an exceptionally rich wildlife there including a large tortoise population. A new holiday village nearby did not appear to threaten the main wildlife areas, and a commercial salt works only operated at the north end of the lake from which access to the heath was not easy. However, unknown to the four members, the 1980 expedition had walked into an explosive situation. The following account is quoted from their report.
The illegal development at Alyki Kitros. Report of the Hellenic Ornithological Society
- P Latsoudis
- G Papakostas
- J Tsougakis
New threat to Alyki tortoises
- A Hailey
Report on environmental effects of the proposed housing developments at the Lake Alyki-Pieria beach Report to the Ministry of Co-ordination and Registrar of the National Council of Physical Planning and Environment
- S Sekliziotis
- A Katsaounis