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Mystery Photo

3-4-19 mystery photo_U1A3795I encountered this scene days ago after a light snowfall when I was on a trail that had been cleared through woodlands last fall. I noticed large bird tracks (present, but not identifiable as such in photo) leading to debris that had been piled just off the cleared trail. Why, I wondered, was any bird attracted to this particular site. As I continued snowshoeing there were several more areas where a similar scene (bird tracks and stumps/logs/branches/sticks) presented itself. What I saw moments later above my head solved the mystery of these scenarios for me. Can you solve it without the revelatory clue I was presented with?

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Hungry Barred Owls Near Feeders

3-4-19 barred owl _U1A2992Over the past few weeks many people in northern New England have discovered Barred Owls perching near their bird feeders during the day. At this time of year, with snow on the ground, food is harder to find and owls are forced to hunt during the day as well as at night. Bird feeders are a sure source of food, as mice and voles are coming out to feed on spilled seed (most often at night).

The owls we see are relying primarily on their sense of hearing to locate small rodents. Their ear openings are asymmetrically placed, which means that sounds reach the owl’s ears at different times. This helps them zero in on the exact location where the sound is coming from, both when they are perched as well as in flight.

Although Barred Owls can detect the sound of a mouse scurrying through tunnels two feet beneath the snow, this winter has been more challenging for them than many. Almost every snow storm has been followed by rain, which has created multiple layers of icy crust. Although sound may be heard through solid, liquid, or gaseous matter, one wonders if these multiple layers of crust compromise an owl’s ability to hear. In addition, these conditions can’t help but impede an owl’s ability to reach its target as quickly as it normally does.

A dear friend whose compassion for creatures big and small is unmatched was going to great lengths (coating balls of hamburger with hair cut from her dog’s coat so they would bear some resemblance to small rodents) to help a resident owl in a time of need. Some would argue that nature shouldn’t be interfered with, but those readers with a desire to come to the aid of a hungry owl could let a little seed fall on the snow that’s packed down around the feeder in hopes that a large supply of accessible food might attract more rodents which might fill more owl stomachs.

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American Black Ducks Vs. Mallards

2-27-19 black ducksAmerican Black Ducks (Anas rubripes), found year-round in all parts of New England except for northern Maine, are nearly identical to Mallards (Anas platyrhynchos) in size, shape and voice. Both have rounded heads, thick bills, and bulky bodies. Like other dabbling ducks they sit high in the water with their tails high. These two closely related species often keep company with each other and it can be challenging to tell them apart, but it is possible to distinguish them with some certainty.

Most of the year male (drake) Mallards have a distinctive iridescent green head, a white neck ring and a yellow bill. However, the female (hen) Mallard’s plumage is very similar to that of both drake and hen Black Ducks. One of the most dependable ways to tell these two species apart is to look for the dark chocolate-colored body of the Black Duck, which is noticeably darker than the hen Mallard’s. At rest, the Black Duck is a uniform very dark brown from the bottom of its neck to its tail. The hen Mallard is a much lighter brown in this area, and in addition has a pale whitish patch on the belly. The color of the bill can also help with identification — the hen Mallard’s bill is orange and black, whereas the Black Duck’s bill ranges from a dusky yellow (drake) to a drab olive (hen) color. All of these identification clues go out the window when hybrids of these two species are encountered! (Photo: American Black Duck drake (L) and hen (R) )

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Porcupine Quills

2-25-19 porcupine IMG_6292Porcupines possess roughly 30,000 quills — hollow, modified hairs which are made from the same material (keratin) as feathers,claws, scales, hairs and fingernails. They cannot “shoot” their quills anymore than we can shoot our hair, but their subcutaneous muscles can cause the quills to become erect as well as loosen them so that when touched, the quills are easily released. Each quill possesses between 700 and 800 barbs along the four millimeters or so nearest its tip. It is these barbs that help a quill remain embedded in the tissue of a predator.

Researchers have found that barbed quills penetrate deeper into muscle than quills without barbs, and require half the penetration force. They have been found to be four times harder to pull out than barbless quills. It has been suggested that the barbs ease the quill’s penetration by concentrating force along the edges of the barbs, similar to how the serrations on a knife blade make cutting meat easier.

Fortunately for porcupines, their quills are covered with a natural antibiotic which protects a porcupine from infection should it be impaled by one of its own quills or one from another porcupine. (Photo: porcupine with quills from another porcupine embedded in nose)

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Male Woodchucks Out and About

2-22-19 woodchuck burrow IMG_0555Hibernation, the true slowing down of one’s metabolism (a Woodchuck’s body temperature drops from 99 degrees F. to 40 degrees F. and its heartbeat drops from 100 beats per minute to 4 beats per minute) is one way an animal conserves energy. Male and female Woodchucks use the energy they’ve conserved very differently in early spring.

At the end of February and in March, males arouse themselves about a month prior to the mating season and spend long periods visiting females and defending their territory. Muddy tracks and trails can be seen near their winter burrows (see photo) at this time of year. Females remain in their burrows in a state of hibernation, saving as much energy as possible for the birth and raising of their young. After confirming the presence of females on their territories, males return to their burrows for the next month or so, awakening along with the females in time for their mating season.

The timing of Woodchuck procreation is not a relaxed affair. It is quite precise, in fact, for very good reasons. If Woodchucks mate too early in the spring, their young won’t be able to find food once they are weaned. If they mate too late, their young won’t have the time necessary for putting on weight and storing fat before hibernation begins. Now is the time to look for signs indicating male Woodchuck activity near their winter woodland burrows.

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Red Feather Tips of Waxwings Indicate Age and Status

2-15-19 cedar waxwing_U1A2000Both Cedar and Bohemian Waxwings derive their common names from the red, waxy tips of some of their secondary feathers. The color of this wax is due to the presence of the pigment astaxanthin. Ornithologists used to theorize that these red tips protected the feathers from wear and tear, but this has not been borne out in studies.

What has been established is that the red appendages increase in both number and size with a bird’s age. Immature birds usually have 0 – 6 waxy tips. Older birds have more than nine. The number of tips appears to function as a signal of age and status in mate selection; individuals within these two age categories choose each other as mates. It also turns out that pairs of older birds (with high numbers of red tips) tend to nest earlier than younger birds. They also have larger clutches and fledge more young than younger birds with fewer waxy tips.

An easy-to-see cue such as these red feather tips that indicate age, maturity and social status at a glance would be very useful in species such as Cedar and Bohemian Waxwings that are often found in large flocks.

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Virginia Opossums Breeding

2-18-19 opossum 025If you see a Virginia Opossum in your travels, it could well be on the hunt for a mate at this time of year. It’s even possible you may hear one if you are close enough and the timing is right, as male opossums attract females by making clicking sounds with their mouth.

The breeding practices of this marsupial are unusual, to say the least. The male opossum has a bifurcated (two-pronged) penis (see photo inset), and the female has two vaginas. Not only is their reproductive anatomy somewhat unusual, but the behavior of their sperm is as well. During maturation, sperm pair up inside the male reproductive tract and remain paired after entering the female. Just prior to fertilization the sperm pair separate (into two spermatozoa). This phenomenon occurs only in American marsupials, and not Australian. No definitive explanation exists for this, but perhaps paired sperm increase motility in the female reproductive tract.

(NB: Having an opossum on your land is a real asset – according to biologist Richard Ostfeld, one opossum can kill and eat some 5,000 ticks in a single season. Opossums are said to destroy roughly 90 percent of all the ticks they encounter.)

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