An online resource based on the award-winning nature guide – maryholland505@gmail.com

Archive for January, 2021

Colorful Cottontail & Hare Urine

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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New Children’s Book Release

My 14th children’s book, Animal Homes, has just been published. It takes a look at the homes of creatures large and small — where they are built, what they are made of, how they are constructed and the ways in which they suit the needs of the animals that inhabit them. From the lodge of a beaver to the bubble home of a young spittlebug, children 4 – 8+ can compare their home with those of others. Copies may be ordered online and in independent bookstores. (For those who follow my family, Sadie, Otis and Lily Piper are featured in their home on the last page!)

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Birds Gathering Grit On Dirt Roads & Roadsides

Birds compensate for their lack of teeth with a two-parted stomach, the first of which (proventriculus) secretes digestive enzymes and the second of which (a muscular gizzard) grinds the food they’ve eaten into small digestible bits.  Birds that eat hard seeds and nuts tend to have thick, muscular gizzards, while those species that eat very easily-digested foods such as soft-bodied insects, soft fruits, or nectar often have very small and thin-walled gizzards.  Many birds whose diet consists of hard substances, including seed-eaters, swallow grit (often why you see them on dirt roads or the sides of plowed roads where dirt has been exposed) to enhance the gizzard’s ability to pulverize food.

At this time of year, American Goldfinches, Common Redpolls, Snow Buntings, Tree Sparrows and Eastern Bluebirds (among others) can be found swallowing roadside grit to help grind up the seeds that they consume.  (Photo:  While a majority of their summer diet is insects, Eastern Bluebirds consume many fruits (containing hard seeds) during the winter, a change in diet that allows them to remain in northern New England throughout the year.)

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Muskrats Foraging

Usually at this time of year, Muskrats are restricted to foraging beneath the ice and eating their mostly herbivorous diet inside “push-ups” — huts made out of excavated vegetation that have been hollowed out and serve as protective outposts where they can eat and rest. Because of warmer weather this winter, many ponds have retained open areas where Muskrats (and Beavers) can climb out of the water and enjoy sunshine (if they’re lucky) and fresh air while they eat.

Unlike Beavers, which store their winter food in a pile adjacent to their lodges in the fall, Muskrats forage for food on a daily basis throughout the winter. While occasionally they eat small fish, clams, snails and turtles, Muskrats’ preferred diet is the roots, stems, leaves, and fruits of many water plants, such as cattail, water lilies, and rushes. Equipped with a thick, waterproof coat of hair, they are capable of remaining submerged up to 15 minutes collecting food due to a decreased heart rate and oxygen stored in their muscles.

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Snow Buntings Feeding

Congratulations to Kathie Fiveash, the first NC reader to correctly identify the tracks and feeding sign in the latest Mystery Photo as those of Snow Buntings (Plectrophenax nivalis).  These birds began arriving in the northern half of the United States from their summer home on the northern tundra last fall and will remain here until March, when they begin migrating back to their breeding grounds.

In the winter, 97% of a Snow Bunting’s diet is weed seeds, including those of knotweed, ragweed, amaranth, aster, goldenrod, grasses and grains. These birds forage on the ground, collecting seeds from the protruding stems of tall weeds, occasionally reaching or leaping up to take seeds from taller stems, jumping against stems to scatter seeds or bending stems over by stepping on them. (Birds of the World, Cornell Laboratory of Ornithology)

While foraging, Snow Bunting flocks are constantly restless, frequently flushing rapidly and low over the ground for short distances.  A flurry of birds, much like snowflakes, fills the air nearest the ground for a few seconds while they relocate to a new area. Birds at the back of the flock fly forward to the front, creating the impression that the flock is rolling along.

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Mystery Photo

If you think you know who has been feeding here, go to the Naturally Curious blog (www.naturallycuriouswithmaryholland.wordpress.com) and enter your answer under “Comments.” (Hint: photo taken in large agricultural field in Champlain Valley of Vermont.) Answer will be revealed on Monday, January 11. (Difficulty 1-10 = 10)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.


What Determines The Internal Air Temperature Of An Active Beaver Lodge In Winter?

Regardless of the outside temperature, the interior of occupied beaver lodges has a fairly stable temperature of about 32°F.  This is due to several factors, one of which is insulation. Beavers spend much of the fall collecting and stuffing mud into the cracks between the branches that provide a framework for their lodge (leaving a mud-free air vent at the top of the lodge).  This mud as well as any snowfall that occurs during the winter help keep out the cold and retain the warmth that the resident beavers’ bodies radiate. 

A comparison of the (cooler) interior temperature of bank dens and that of open-water lodges confirms that the temperature of the substrate underlying a lodge also contributes to the air temperature of the chamber.

Lastly, heat produced by beavers raises the temperature of a lodge above that derived from the lodge substrate.

(Photo: beaver lodge on a morning cold enough to show “beaver breath” escaping through the air vent that runs up through the center of the lodge to its peak. Thanks to Kay Shumway for photo op.)

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Fish are a primary, but not exclusive, food source for Bald Eagles

Hands down, Bald Eagles (like the 2nd year immature bird pictured) prefer fish over other prey — roughly 56% of the diet of nesting Bald Eagles consists of fish such as salmon, herring, shad, and catfish.  However, eagles are opportunistic foragers and over 400 species of prey have been recorded, half of which are waterbirds. Reptiles, amphibians, invertebrates such as crabs and crayfish, and small mammals such as squirrels, rabbits, muskrats, young beavers, fawns and raccoons are also subject to Bald Eagle predation.

During their first year, until they learn to be proficient hunters, Bald Eagles frequently feed on carrion. Even as adults, eagles regularly consume roadkills and deer that have died as a result of being stranded on ice. Whatever food is available and requires the least amount of energy to capture is usually high on their list.

Although not considered a primary source of food, domestic pets are subject to occasional predation by eagles. A discovery made by Fish & Wildlife personnel engaged in banding Bald Eagle nestlings may be of interest to cat owners who allow their pets to roam free in the great outdoors.  Upon reaching one nest, they found, among the detritus, over 20 cat collars.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.