У обыкновенного ужа в Среднем Поволжье и Камском Предуралье выражена смена весеннего (осеннего) и летнего биотопов, формирующая смену температурных и других микроклиматических условий среды. Наибольшая температура тела ужа в Предуралье отмечена в сентябре. Самый тёплый субстрат ужи выбирают в апреле-мае. Температура тела и внешние температуры изменчивы по годам. От северной границы ареала до Прикаспийской низменности у обыкновенного ужа практически нет географической изменчивости температуры тела. Эксперимент с вшитыми в тело ужа логгерами iBDL показал, что температурный минимум тела в период дневной активности находится в интервале 13,6-16,0˚С. Максимум – в интервале 32,6-36,6˚С. Оптимум температуры воздуха – 21,2-26,0˚С, температуры тела – 26,3-31,0˚С. В целом температура тела обыкновенного ужа сильно зависит от внешней температуры, но в период дневной активности эта зависимость сильно снижается.
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432Приводятся данные о питании обыкновенного и водяного ужей в Волгоградской области. Половину рациона обыкновенного ужа составляют земноводные, представленные озерной лягушкой (50,0%). Другую половину добычи занимают рыбы семейства карповые (31,3%) и жуки, не определенные до вида (18,7%). В пище водяного ужа обнаружены исключительно рыбы, среди которых преобладает серебряный карась, составляя 68,7% экземпляров от всей проглоченной пищи.
В наших экспериментах было доказано, что первичной реакцией ужей ( Natrix natrix ) на любой источник света является стремление к нему – фототаксис. Змеи всегда выбирали место с наибольшей освещенностью. Стремление к теплу – термотаксис – был вторичным по отношению к фототаксису. Было установлено, что при скорости вращения оптомоторного барабана 2 об./мин. реакция следования за полосами максимальна и превышает число поворотов при различной освещенности. Понижение температуры ниже 0 °C, как и повышение освещенности выше 500 Лк, приводят к учащению и ускорению движений змей.
В настоящей работе обсуждаются региональные особенности биологии, экологии и морфологии ужа обыкновенного, показано распространение вида на территории Волгоградской области, дана характеристика подвидов на основе метрических и меристических признаков. Проанализированы основные показатели, применяемые в систематике вида.
Несколько лет наблюдений понадобилоcь биологу и фотографу Николаю Шпиленку, чтобы собрать уникальную коллекцию запечатленных на пленку сцен из жизни обыкновенных ужей. В природе они избегают встречи с человеком, поэтому многие факты из их "биографии" остаются под покровом тайны
The interrelationships between body size, sexual differences and growth rates of European grass snakes were studied. Two-factor analysis of variance and covariance were used in the analysis of the relationships. Results indicate that prey availability causes the marked differences in adult body sizes and the degree of sexual size dimporphism among populations of grass snakes without any genetic modifications involved
Injuries of various types are widespread in animals and presumably have implications at the population level (e.g. reduced future survivorship). We studied patterns of injury acquisition in a population of grass snakes (Natrix natrix) in south-eastern England. Injuries suffered by grass snakes were of various types, including broken bones, assorted scars and wounds, and tail loss. What causes such injuries is unknown, but predators seem most likely. We predicted that the probability of having an injury would be higher for larger snakes, for several reasons (e.g. larger snakes are older and thus have had more opportunity to be injured). We also predicted that injury rates would be higher in females because, when gravid, they are expected to bask in the open more than other snakes. Our data strongly supported the first of these predictions, but not the second. Males had significantly higher injury rates than females of the same body size. However, because males grow more slowly and mature at a smaller body size than females, higher injury rates of males might simply reflect their smaller size at a given age. Even if age plays a role in influencing acquisition of injuries, other, more directly size-related factors also might be important. Two possibilities are that small snakes might be less likely to survive an injury or that small snakes spend more time hidden and so are less likely to encounter large predators. We lack data on the first of these, but data on sizes of snakes found under cover versus those found in the open are consistent with the second. Studies of injury rates in snakes need to move beyond the descriptive stage and begin to test the broader consequences of injuries.
The diet of grass snakes (Natrix natrix) on the mainland and an island of Italy was compared by pooling literature data and original data. A total of 535 prey items were recorded (444 prey items from specimens >40 cm SVL), but the number of items was very variable between sites. Body lengths (both sexes) varied between geographical areas, and females were larger than males in all study areas. Specimens from the island (central Sardinia) and from one mainland mountainous locality (Duchessa Mountains) were significantly smaller than those from all the other localities. Amphibians were the main prey for both sexes, but females ate more toads and fewer frogs or tadpoles than males; females also consumed more rodents than males. There was a strong effect of locality on diet composition i.e. newts/salamanders were found only in two montane areas; hylids were found only in the single island area; and rodents were commonly preyed upon only at a single mainland locality. Two lizard corpses (Podarcis muralis) were scavenged by grass snakes at a mainland locality. The presence of the piscivorous snake Natrix tessellata, a potential competitor for food, did not have any apparent effect on the food types eaten by grass snakes because grass snakes consumed fish when sympatric with N. tessellata, but not at other sites. The dietary variation exhibited by grass snakes suggests that, by shifting their diets to other prey, they might be able to persist in areas where their usual natural prey has declined drastically, but this remains to be demonstrated.
A five-year mark-recapture study at Sella Nevea, a montane (1100 m a.s.l.) site in the Carnie Alps, provided information on diets, growth rates, and reproductive output in an Italian population of the wide-ranging grass snake, Natrix natrix. Our snakes resembled a previously-studied population in lowland Sweden in terms of body size at sexual maturation in females (70 cm) and mean adult female body length (82 cm). However, growth rates were lower in our population, and sexual maturation was delayed (6-8 years, versus 4-5 years in Sweden), perhaps because of the cool climate and relatively brief growing period each year. Females produced a single clutch of 4-24 eggs in late July each year. Larger families produced larger clutches, but clutch size relative to maternal size was lower than in Swedish grass snakes. Hatchling sizes and Relative Clutch Masses (RCMs) did not shift with increasing female size. RCMs may provide a useful index of 'costs of reproduction' in this population, because females with high RCMs were very emaciated after oviposition, and hence may experience a greater risk of mortality, as well as a high expenditure. Prolonged incubation gave rise to longer, thinner hatchlings, but the low environmental temperatures at the study site may favour early hatching (and hence, result in a shorter fatter hatchling emerging from the egg, with more of its energy stores unused). Compared to sympatric viviparous snakes (Coronella austriaca and Vipera berus), the oviparous grass snakes can achieve a much higher reproductive output owing to a larger clutch size and more frequent reproduction (annual, rather than biennial or triennial). The abundant prey resource used by grass snakes (amphibians) may also enable them to recoup energy more rapidly after reproduction; dietary composition shifts ontogenetically in both sexes, with the largest prey (mice and adult toads) taken primarily by large female snakes.
Grass snakes (Natrix natrix) represent one of the most widely distributed snake species of the Palaearctic region, ranging from the North African Maghreb region and the Iberian Peninsula through most of Europe and western Asia eastward to the region of Lake Baikal in Central Asia. Within N. natrix, up to 14 distinct subspecies are regarded as valid. In addition, some authors recognize big-headed grass snakes from western Transcaucasia as a distinct species, N. megalocephala. Based on phylogenetic analyses of a 1984-bp-long alignment of mtDNA sequences (ND4+tRNAs, cyt b) of 410 grass snakes, a nearly range-wide phylogeography is presented for both species. Within N. natrix, 16 terminal mitochondrial clades were identified, most of which conflict with morphologically defined subspecies. These 16 clades correspond to three more inclusive clades from (i) the Iberian Peninsula plus North Africa, (ii) East Europe and Asia and (iii) West Europe including Corso-Sardinia, the Apennine Peninsula and Sicily. Hypotheses regarding glacial refugia and postglacial range expansions are presented. Refugia were most likely located in each of the southern European peninsulas, Corso-Sardinia, North Africa, Anatolia and the neighbouring Near and Middle East, where the greatest extant genetic diversity occurs. Multiple distinct microrefugia are inferred for continental Italy plus Sicily, the Balkan Peninsula, Anatolia and the Near and Middle East. Holocene range expansions led to the colonization of more northerly regions and the formation of secondary contact zones. Western Europe was invaded from a refuge within southern France, while Central Europe was reached by two distinct range expansions from the Balkan Peninsula. In Central Europe, there are two contact zones of three distinct mitochondrial clades, and one of these contact zones was theretofore completely unknown. Another contact zone is hypothesized for Eastern Europe, which was colonized, like north-western Asia, from the Caucasus region. Further contact zones were identified for southern Italy, the Balkans and Transcaucasia. In agreement with previous studies using morphological characters and allozymes, there is no evidence for the distinctiveness of N. megalocephala. Therefore, N. megalocephala is synonymized with N. natrix.
