With snow on the ground, it becomes evident that the urine of Eastern Cottontails, New England Cottontails and Snowshoe Hares is occasionally colored red or blue! This is not indicative of disease — it is a result of their diet.
Phytochemicals are responsible for this oddity. Plants contain compounds that contribute to the plants’ color, taste and smell. When the plants are eaten by a rabbit or hare, these compounds pass through the animal’s system and come out in its urine, affecting the urine’s color. I am not aware of which plants produce the more commonly seen red urine, but compounds in the twigs and bark (the fruit is not often eaten by hares and rabbits) of the invasive European Buckthorn (Rhamnus cathartica) can turn rabbit and hare urine blue. (Initially the urine is yellow, but after about ten minutes’ exposure to the sun, it turns blue.)
As winter progresses, your chances of seeing blue urine increase, as much of the easily accessible nutritious food has been harvested and rabbits and hares resort to eating the less desirable twigs and bark of European Buckthorn. (Photo: Snowshoe Hare tracks and urine)
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There are two species of cottontails in the Northeast – the New England Cottontail and the Eastern Cottontail. The New England Cottontail was the only rabbit east of the Hudson River until the Eastern Cottontail was introduced in the late 1800s. Today the New England Cottontail is restricted to less than a fifth of its range in the early 1900s, whereas the Eastern Cottontail can be found throughout New England.
Although they are two separate species, these two rabbits look very similar – the Eastern Cottontail is slightly larger, has longer ears, and its eyes are half again as large as the New England Cottontail’s. The New England Cottontail is a forest species that depends on areas of thick shrubs and young trees that grow up following natural disturbances. A combination of dwindling habitat due to development, the ephemeral nature of young forests (they only last for 10 to 20 years before becoming older woodland, where ground-level plants are too thin to provide rabbits with enough food and cover to survive) and inferior eyesight has led to the dwindling population of New England Cottontails, and fostered the growth of the Eastern Cottontail population. Eastern Cottontails seem better able to survive in the increasingly fragmented habitats of New England, including open fields, forest edges, small thickets, and even golf courses and suburban lawns. (Photo: Eastern Cottontail)
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Rabbits and hares generally deposit their scat pellets one at a time, so when you find several in one spot, you know they’ve been there a while, either eating or resting. The little round, brown, fibrous rabbit and hare pellets we are familiar with have actually been ingested twice – a process referred to as coprophagy. On its first passage through the digestive system, bacteria act on the food in the large caecum (a pouch near the start of the large intestine, which most herbivorous mammals possess) reducing it to a more easily digestible form and concentrating it, particularly its vitamin B and protein content.The caecum, however, is past the portion of the digestive tract in which most resorption takes place. It is therefore necessary for the animal to reingest the resulting pellets, which are soft and green and covered with mucous, to extract as much of the nutrition as possible. These soft pellets are eaten directly from the anus. Coprophagy increases protein digestibility from 50 percent in one pass through the digestive system to 75 to 80 percent upon reingestion. Cellulose digestion is increased from 14 percent in one pass through the digestive system to two or three times that amount when the feces is re-ingested.