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Adaptations

White-winged Crossbills Nesting

White_winged crossbill by garth mcelroyrWhite-winged Crossbills inhabit the boreal forests of northern New England, the southern edge of their breeding grounds. This species, as well as Red Crossbills, are named for their bill which is supremely adapted to extracting seeds from conifer cones. Crossbills use their crossed bills to wedge open cone scales, after which they lift the seeds free with their tongues. Individuals can eat up to 3,000 conifer seeds per day.

White-winged Crossbills are erratic nesters that have been found breeding every month of the year. The birds nest whenever the available food supply is sufficient for egg formation and is likely to remain sufficient for at least three weeks, during the more energy demanding nestling stage.

Three nesting periods have been observed, each corresponding to the ripening of cones from different conifer species. The first season occurs in early July, when the cones of Tamarack, or American Larch, and White Spruce mature. The second nesting period begins in January and February, when they rely mainly on White and Red Spruce cone crops and the third season is starting now, as Black Spruce cones begin to open up. (Photo: public domain, male White-winged Crossbill)

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Owls & Humans Share Trait

barred owl 194Birds have three eyelids – an upper eyelid, lower eyelid and a third semitransparent membrane called a nictitating membrane that sweeps across the eye much like a windshield wiper. This membrane keeps their eyes moist, and protects their corneas from being scratched.

In most birds, including owls, the upper and lower eyelids are used to close the eyes when sleeping, and the nictitating membrane is used for blinking. Humans close their eyes mainly by lowering the upper eyelid, where most birds do so by raising the lower lid. Owls (and a few other birds such as parrots, toucans, wrens and ostriches) are more human-like in that their upper lids are usually lowered to close their eyes. Owls also usually close their eyes, partly or entirely, when capturing and transferring prey, scratching their face, preening another owl and copulating. (Note the rows of feathers on this barred owl’s upper eyelids.)

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Time To Take Down Bird Feeders

3-17-15 black bear-eating sunflower seeds  IMG_3607To prevent black bears from visiting backyard bird feeders, Fish & Wildlife Departments in New England recommend taking down birdfeeders from April 1st through December 1st. This year those dates are fairly conservative, as bears were visiting feeders after December 1st, and several have been seen frequenting feeders this month. The idea is to remove anything outdoors that would be of any interest to a bear which has just emerged from hibernation and is desperate for food.

Approximately 85% of a bear’s diet is vegetation. Before green shoots make an appearance in the spring, flower parts of aspen, willow, maple, ash and hazelnut, along with carrion, make up most of a bear’s diet. After losing 23% of its body weight during hibernation, a black bear finds protein-packed sunflower seeds very appealing. Make sure your garbage is secured, barbeques clean and pet food kept indoors, as well as your feeders. Keeping bears away not only prevents property from being damaged, but it also prevents bears from becoming nuisance animals that are habituated to food associated with humans, which often leads to the end of a bear’s life.

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Patient (and Hungry) Barred Owls Visit Feeders

3-12-15 barred owl 152Barred owls are nothing if not resourceful when it comes to methods for finding food. Typically they sit on a high branch and scan the area for prey before dropping down to capture small mammals such as mice, squirrels as well as reptiles and amphibians. During summer months, they have been seen perched over water and swooping down to capture fish, as well as wading in shallow water to hunt for crayfish and fish. Barred owls have even been seen running along the ground and pouncing on amphibians.

Even with a myriad of hunting techniques, however, barred owls have had a hard time this winter, due to the depth of the snow (harder to hear and reach prey) and the time it is taking for it to melt. Small mammals, which compose the bulk of their diet, remain well hidden. Reports of barred owls perched patiently waiting and watching on or near bird feeders for unsuspecting rodents to expose themselves have become commonplace. Mice and voles that come out from under the snow to feed on spilled seed during the night are a life-saving source of food for these stressed birds. Warmer weather will hopefully soon improve hunting conditions for barred owls. Their gain will be our loss, for once again, as it should be, a sighting will become a far more rare occurrence. (Thanks to Emily and Joe Silver for photo op.)

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Porcupine Cecum

3-6-15 porcupine2 IMG_5163Your guesses were outstanding – especially “Pinocchio scat” and “petrified baby hippopotamus”– and a couple of readers even nailed it: part of the intestines of a porcupine. (Many of you suggested it might be a black bear’s fecal plug – not a bad guess – though any bear that had to pass something this large when it woke up might decide to hibernate year round.)

Mystery Photo Explanation: A fisher killed and ate a porcupine, choosing not to eat (and leaving behind) a portion of the porcupine’s digestive tract called a cecum – a sac located between the large and small intestine where the cellulose in leaves and bark that a porcupine eats are broken down.

During the warmer seasons of the year, porcupines feed on sugar maple buds, leaves of basswood, aspen and beech saplings, grasses and other herbaceous plants, apples, acorns and beech nuts. In winter, their diet consists mostly of leaves (mainly eastern hemlock in the Northeast), which contain low levels of nutrients and high levels of dietary fiber. Certain mammals and birds possess specific bacteria that secrete enzymes capable of digesting the cellulose in fiber (beavers, hares, rabbits and ruffed grouse come to mind) through the process of fermentation. Because these enzymes work slowly, the digestive tract of a porcupine is very long (26% of a porcupine’s total weight) and the fiber passes through it slowly.

A majority of the bacterial activity in a porcupine’s digestive system takes place in the cecum, which is about the same size as a porcupine’s stomach. Here fermentation turns finely ground woody material into molecules small enough to be absorbed by the porcupine’s body. (A process referred to as “hind gut fermentation.”) Research shows that 16% of a porcupine’s energy requirements are supplied by the porcupine’s cecal fermentation.

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Snowshoe Hare Hind Feet

2-27  snowshoe hare back foot 011It is not hard to see why the individual toe pads in the tracks of a snowshoe hare’s feet are rarely very distinct. There is a 3/4”- thick layer of hair on the bottom of a hare’s 5- to 6-inch-long hind foot. This hair, along with the size of the foot and the ability of the hare to spread its toes to a width of five inches allows the hare to stay on or near the surface of the snow, and, in the right snow conditions, outrun heavier predators.

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Black Bear Dens

2-25-15 bear dens1Black bears den in a range of locations, including under logs and stumps, under the branches of a fallen tree, and inside caves and hollow trees. Most adult black bears are not completely protected from the elements while they are hibernating and/or raising cubs, as there is usually a fairly large opening and the bear is exposed to the cold air. The amount of exposure can vary tremendously, from a relatively protected hollow under a log to complete exposure within a dense thicket or stand of conifers. Pictured are two black bear dens where cubs were raised; one is under a fallen tree and the other is in the middle of a stand of spruces.

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