Black Rat Snakes Research Articles

Over a 15-year period, 359 black rat snakes were captured, mostly on a 750-acre area; because many were recaptured after marking, records totaled 516. The average emergence date was 16 April and 27 October was the average date for the end of the season's activity. Calculated home ranges averaged 29 acres for males and 23 acres for females. Males are more inclined to wander, but in both sexes the tendency to remain within a familiar range is strong. Hatchlings appear in late summer or early autumn and range in snout-vent length from 290 to 368 millimeters; typical one-year-olds range from 500 to 650 millimeters. Sexual maturity is attained in the fourth year usually at a snout-vent length of a little less than 900 millimeters in males (which usually mature somewhat earlier) and a little more than 900 millimeters in females. Monthly gains in the growing season average 36 millimeters in the young of each sex. In the third or fourth year there is abrupt slowing, most marked in the females. Large adult males gain on the average a little more than three millimeters per month in the growing season. On the basis of observed growth rates more than one-fourth of the rat snakes recorded were eight years old or older, and some may have been more than 20 years old. The rat snake depends primarily on small birds and mammals for food, but takes an occasional frog, lizard, or snake. Birds are preyed upon chiefly in the nesting season; few adults are eaten. The red-tailed hawk is an important natural enemy; 577 instances of predation on rat snakes were recorded for this kind of hawk, but for other predators few records were obtained.

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