Species Of Water Snakes Research Articles

Body Size Dimorphism and Sexual Selection in Two Species of Water Snakes

Body Size Dimorphism and Sexual Selection in Two Species of Water Snakes

The Role of Temperature on the Behavioral and Ecological Associations of Sympatric Water Snakes

Several aspects of the thermal ecology of five sympatric water snake species were explored quantitatively. Body temperatures of captured snakes are compared to ambient temperatures at the capture site and evaluated in terms of daily and seasonal activity patterns. Three species of water snakes, Nerodia rhombifera, N. cyclopion and N. fasciata, account for 86% of this snake community. Each species has a relatively distinctive usage of the arboreal and aquatic habitats and each has a characteristic activity pattern. A fourth congener, Nerodia erythrogaster is uniformly nocturnal (77% of census data) and aquatic (88%). The fifth species, Regina grahamii was seasonally asynchronous with Nerodia spp. and was the most arboreal member of the community (84%). N. cyclopion was the only species active in all months of the year. During the cool months (Nov.-March) it was primarily a diurnal perching snake (70-90% of census), and during the summer N. cyclopion was nocturnal and aquatic (82100%). The trend toward becoming nocturnally active in the summer was characteristic of all Nerodia spp. N. rhombifera, however, became much more arboreal during the summer months. N. fasciata was uniform in habitat usage for most of the year (60% aquatic) but did not become nocturnal until June a month or two after congeners. Observed year to year variations in mean body temperature of each species reflected climatic fluctuations over the four years of study. The data indicate that only one species, N. cyclopion, makes seasonal adjustments of daily activity periods and arboreal tendencies that maintain fairly uniform body temperatures even through the cool months. When the thermal axis of the fundamental niche is considered in light of available data on the food, time, and space axes, the influence of temperature on this ectothermic community appears to be significant. In summary, we maintain that the underlying mechanism for the asynchronous daily and seasonal patterns of habitat use is specific differences in thermal niches. The two most ecologically similar species do not appear to be in competition for thermal niche space, but rather partition the thermal resource to reduce interference competition.

Chemical Preference Studies on Newborn Snakes of Three Sympatric Species of Natrix

Newborn young of three sympatric species of water snakes (Natrix) were tested with water extracts of a variety of small animals including fish, earthworms, amphibians, slugs, crickets, baby mice, and crayfish. N. s. sipedon responded with increased tongue flicking only to fish and amphibian extracts. N. grahamii and N. septemvittata responded only to crayfish extracts, and most strongly to extracts prepared from newly molted crayfish.

Renal function in water snakes.

Electrolyte and osmolar concentrations of ureteral urine were compared with serum in several species of water snakes. Hyperosmotic urine was never observed, even after 48 hr of water deprivation. This finding is consistent with the countercurrent theory which precludes urinary concentration when Henle's loops are absent, as in reptilian kidneys. The creatinine/inulin clearance ratio may exceed 2.0, suggesting tubular secretion of creatinine. Tubular secretion is further suggested by the fact that the clearance ratio approaches unity when plasma creatinine concentration is elevated. Variations in glomerular activity are reflected in urine flow in snakes as shown by a direct relationship between clearance of inulin (GFR) and urine flow In snakes solute excretion is dependent on an increase in functional tubular population, with a concomitant increase in filtered load and not a decrease in tubular solute reabsorption. Evidence for this concept is presented and indicates that, over a tenfold increase in GFR, snakes continue to excrete about the same per cent of their filtered load. Water reabsorption, on the other hand, appears to be similar in character to that seen in higher vertebrates. Proximally, it appears to be dependent on solute reabsorption ("obligatory"), whereas distally it is influenced by ADH ("facultative").

Heart rate and blood lactic acid concentration during experimental diving of water snakes.

Bradycardia in response to submersion occurs in Natrix sipedon and Natrix cyclopion. Atropine will prevent this diving bradycardia. Blood lactic acid concentration does not increase during submersion, indicating the presence of an arterial constrictor response in these species of water snake. The diving phenomenon of the water snake appears similar to the diving phenomenon of the seal in that both diving bradycardia and arterial constrictor response occur.

A Comparative Study of Selected Characters in Certain American Species of Watersnakes

It has long been well known that the American watersnakes of the genus Natrix embrace a group of small species very distinctively different from other members of the genus. This, the Regina group, consists of four species: N. grahami (Baird and Girard), N. septemvittata (Say), N. kirtlandi (Kennicott), and N. rigida (Say). The present study is an investigation of the degree of skeletal distinction existing between this group and other American Natrix as exemplified by the three species and subspecies N. s. sipedon (Linne), N. erythrogaster transversa (Hallowell), and N. r. rhombifera (Hallowell), all referred to here for the sake of convenience as constituting part of a sipedon group.

Food and Growth of Two Species of Watersnakes from Western New York

l ITTLE information on food habits based on the examination of stomach contents is available for the queen snake, Natrix septemvittata (Say). The few scattered data indicate crayfish are the most important food, a fact fully substantiated by this study. The common water snake, Natrix sipedon sipedon (Linnaeus), eats mostly fishes and amphibians, and smaller amounts of insects and mammals. This study is concerned with the food habits of the two species taken in the same habitat.

Pre- and Post-Hunting Season Foods of Raccoons on an Illinois Goose Refuge

Field studies were supplemented by laboratory analyses of 344 scats collected in all months and of 23 stomachs and 11 intestines obtained in winter. Acorns and crayfish constitute more than half of the yearly diet and both are consumed in considerable amount at all seasons. Persimmons and grapes were utilized heavily when available and other fruits in smaller amounts. Insects and other invertebrates formed an important part of the diet. Vertebrates were eaten sparingly but species of water snakes were preyed upon as were winter and spring concentrations of water fowl. Raccoons were found to concentrate in timbered river bottoms during the winter and spring, feeding largely on acorns and crayfish. Under these conditions they are readily trapped. In the summer and autumn the populations appear to be dispersed through the uplands as well as bottomlands in search of seasonal foods.