Ecology and conservation of the Milos viper, Macrovipera schweizeri (Werner, 1935)
| Autor: | Yiannis Ioannidis, Claes Andrén, Göran Nilson, Maria Dimaki |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Amphibia-Reptilia. 20:355-375 |
| ISSN: | 1568-5381 0173-5373 |
| Popis: | Abstract The Milos viper (Macrovipera schweizeri) is nocturnal from early summer until mid-September. The typical habitat was maquis terrain with small and large bushes on gravel or rocky ground. Telemetric studies showed that cryptic basking behaviour was used during 23.5% of the localisations, and a preference for large bushes (77.7%). The mean distance moved between two succeeding days was 28.5 m (with s_x, of 47.9), and in general, the male home range covered an area of 10 to 20 ha, while the female home range was smaller. Hibernacula were south facing and situated in the middle of the home ranges. Population density was 50 adult vipers per km2 in the optimal habitats. The total population for western Milos was estimated to be around 2,500 adult vipers during the study period (1993-98). The present total population on Milos seems to be below 3,000 adult animals. The species has been isolated since the Pliocene, and adapted to a diet of passerine birds. A pattern of twice-a-year foraging during spring and autumn bird migrations was highlighted. During spring, the vipers tend to be concentrated around water pools; in the dry autumn nights they climb up trees for resting birds. In years with a cold spring or autumn, critical situations may occur with starvation, resulting in cyclic population patterns. Mid-May is the mating period. The female reproductive cycle is biennial. The sex ratio is nearly equal. Around 600 specimens reach adulthood and participate in the reproductive activities each year. Mining and fires destroy habitat. The yearly estimated removal by man and road killing of vipers is up to 500-600 adult specimens. Thus, the input and out-take of adult specimens is of the same magnitude, and equal to a yearly 25% turnover. This indicates a very delicate balance, and even a small change that increases the removed number can lead towards a rapid extinction. A conservation program is urgently needed and should include the establishment of protected areas, the closing of roads for night-time driving, and prohibition of increased mining activities. |
| Databáze: | OpenAIRE |
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