Merry Christmas!
A very Merry Christmas and the happiest of holidays to all of my readers! Having spent the past two years writing a sequel to Naturally Curious (Naturally Curious Day by Day, due out next fall), and having just submitted the manuscript, I’ve decided to recharge my batteries in the coming days. I hope that my readers will understand and tune in when posts resume on January 4, 2016. Thank you for your support, your comments, your corrections, your loyalty and most of all, for providing me with the opportunity to share my passion with kindred spirits.
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Beavers To The Rescue
With peepers peeping and pussy willows starting to poke their heads out of local willows in mid- late December, it is clear that in the coming years humans will need to adapt to the effects of climate change. Help with that mission may come from many sources, including beavers, whose landscape alterations have been shown to mitigate many of the more extreme conditions caused by climate change. “ Where beaver dams are persistent, they may sequester sediment and create wet meadows that can moderate floods, augment early summer baseflows, sequester carbon in soils and standing biomass, decrease ecological problems posed by earlier spring stream recession, and potentially help cool early summer and post-wildfire stream temperatures. “ (Jeff Baldwin, California Fish & Game) How fortunate that silk hats became fashionable in the early 1800’s, decreasing the demand for beaver pelts and rescuing beavers from extinction.
Meadow Vole Nests
Meadow voles (Microtus pennsylvanicus), tiny mouse-like rodents, spend a majority of their time on the surface of the ground, particularly in moist fields filled with grasses and sedges. They have elaborate runways through the vegetation – well-worn trails about the width of a garden hose which they keep mowed down with their incisors. Latrines of small brownish-green pellets can be found intermittently along the trails.
Most meadow vole nests are constructed out of dried grasses, also on the surface of the ground, although they are sometimes built at the end of shallow burrows. When above ground, the nests are often located in the center of a grass tussock, where they are less apt to be flooded. When there is snow on the ground they are a bit easier to find, as the heat of the voles inside the nest melts away the snow, forming a chimney that sometimes reveals the nest below.
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Promethea Pupae Parasitized
Although a lack of snow makes tracks difficult to find, there are other, more permanent, animal signs such as bird nests and cocoons that are visible this time of year. Among the more obvious is the cocoon of the Promethea Moth – a giant silk moth. When the time for pupating arrives the Promethea caterpillar selects a leaf and strengthens its attachment to the tree by spinning silk around the petiole of the leaf as well as the branch it grows on (to assure that it doesn’t fall off the tree). With more silk it rolls the leaf up into a tube and then proceeds to spin its cocoon inside the rolled-up leaf, leaving a valve-like structure at the top of the cocoon through which the adult moth exits in the spring.
Unfortunately for silk moths, many are parasitized by flies and wasps (there are nearly 100 natural parasites that affect the 24 species of silk moths east of the Mississippi River). Frequently flies or wasps lay their eggs in silk moth caterpillars and then develop inside them. Eventually the fly or wasp larva secretes a substance that causes the caterpillar to pupate, at which time the fly or wasp also pupates and then exits the moth pupa and cocoon (see exit hole in smaller photo), causing the death of the moth pupa. Silk moth populations are decreasing, in part as a result of these parasitoids. Among others, a non-native parasitic tachinid fly, Compsilura concinnata, is wreaking havoc on silk moths.
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Live Web Cams Bring Wildlife to You
With no snow to reveal wildlife tracks and traces, and cold, rainy weather that after a certain point discourages even the most ardent naturalists, there comes a time when the computer can almost compete with the great outdoors. Want to see Tawny Frogmouths in Australia? Green-headed Tanagers feeding in Brazil? Bald Eagles nesting in Florida? Bananaquits feeding in Bonaire? All this and more is available with one or two taps of your finger.
Live webcams have been set up to record activity at hundreds of sites that wildlife frequent. To view feeders and the avian visitors they attract, go to http://www.viewbirds.com/feeders.htm and choose what part of the world or which species of bird you wish to observe. Some birds in warmer climates are nesting now, and archived highlights as well as live nest coverage from all over the world can be found by going to http://www.viewbirds.com/. Activity at an African watering hole can be monitored at http://www.apl.tv/explore-watering-hole.htm (11:30 a.m. – 12:30 p.m. EST is best time to watch). The possible viewing opportunities are endless. You may wish to consult Audubon’s list of the 10 best wildlife webcams at https://www.audubon.org/news/top-10-wildlife-web-cams — cranes, wolves and birds are just some of the creatures that serve as the focus of these webcams. (Photo: Sandhill Crane. Migrating birds stopping to refuel at the Platte River in Nebraska in March can be seen at http://www.ustream.tv/channel/rowe-sanctuary-s-crane-cam.)
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Spring Peepers Peeping
The sound of a peeping Spring Peeper in December (yes, this occurred in Vermont this week) conveys to one and all that climate change is not a figment of our imagination. Amphibians are extremely sensitive to small changes in temperature and moisture due to their permeable skin and shell-less eggs. Certain species, including Spring Peepers, Grey Tree Frogs, Wood Frogs, American Bullfrogs and American Toads, are emerging and mating earlier in the year than they did historically. Causal relationships have been found between irregular climate conditions (drought, increasing frequency of dry periods and severe frosts) and decreasing (extinction in some cases) of certain amphibian species.
Behaviorally and physically, warming temperatures are having an impact on amphibians. A recent laboratory study investigated changes in amphibian metamorphosis time due to pond desiccation and whether amphibian immune systems become compromised as a result of these changes. They found that amphibian immune responses became increasingly weaker and white blood cell counts were increasingly lower with higher desiccation. As a result of climate effects, immune systems are weakened, making it more difficult for amphibians to fight off diseases.
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Mycelium
Yesterday’s post on fungal hyphae inspired a very talented naturalist/author to send me a poem she had written about the same subject. I was so taken with her poem that I asked permission to share it with you today. I hope it speaks to you as it does to me. (A mass of hyphae is referred to as mycelium.)
Mycelium
The mole has it at her fingertips, the slug
finds it delicious, the chipmunk
is a connoisseur of its networks,
under the deer’s sharp hooves,
it is broken and healed.
It is a blanket woven
in the bed of the earth.
It is patient as the desert,
willing to wait
a month or a season
for the engorgement of rain,
the carnal urgency of fruit ,
the ethereal casting of spores.
Some believe they know
about the longings of trees,
their reachings for the sky,
their intimacy with the air,
but a tree meets its true lover
in a secret tryst under the earth,
in the clasping of root tips
the sheathing, the enfolding,
the flowing back and forth,
the quenchings and bodily gifts
of the mycorrhyzal embrace.
Kathie Fiveash, author, Island Naturalist
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Mycorrhizal Relationships
The woods are filled with all kinds of plants – herbaceous and woody, flowering and non-flowering. Each plant appears to be independent of all others, but this is an illusion. In fact, most of the plants in a forest are physically connected to one another. How and why this is so is a little known fact.
Fungal threads called hyphae (the subterranean body of a fungus that we don’t usually see) run throughout the soil. Each one is ten times finer than a plant’s root hair. While some are digesting dead organic matter, others are forming a relationship with photosynthetic plants. This mutually beneficial relationship between fungi and plants is referred to as mycorrhizal.
The very fine fungal threads are capable of penetrating plant cells, allowing the fungus to receive sugars that the photosynthetic plant has manufactured. At the same time, the fungus provides the plant with minerals (especially phosphates) it has garnered from the soil. Nearly all plants have mycorrhizal fungi wrapped in or around their roots, and many of these plants cannot live without their fungal partners. The real work of a plant’s roots may well be to serve as the connector to this network of fungal hyphae that exists in the soil. (photo: Eastern White Pine,Pinus strobus)
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Scat Revelations
Predators and scavengers of all stripes are reaping the benefits of deer hunting season. A close look at the composition and form of the pictured scat reveals much more than the fact that a coyote dined on a white-tailed deer. Note that the scat consists almost entirely of deer hair. When a predator such as a coyote comes upon a carcass, it tends to eat the internal organs first, which produce black, moist, soft scats with next to no bones or hair in them. As it continues to feed, the coyote’s scats contain more and more bones and hair, until eventually that is all they consist of.
There are two conclusions one could make when analyzing this scat. One is that the coyote whose scat this is was finishing up the tail end of a deer carcass. It is also possible that this coyote might not have been at the top of its pack’s hierarchy. The alpha pair usually has first dibs on the internal organs, with lower members of the pack having access to the less choice parts, such as hair and bones.
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Goldenrod Ball Galls Provide Important Source of Winter Food for Downy Woodpeckers
A number of insects cause goldenrod plants to form galls – abnormal growths that house and feed larval insects. The Goldenrod Ball Gall is caused by a fly, Eurosta solidaginis. The fly lays an egg on the stem of a Canada Goldenrod (Solidago canadensis) plant in early spring, the egg hatches and the larva burrows its way into the stem; the plant reacts by forming a gall around the larva. The larva overwinters inside the gall, pupates in late winter and emerges in early spring as an adult fly. Prior to pupating, the larva chews an exit tunnel to, but not through, the outermost layer of gall tissue. (As an adult fly it will not have chewing mouthparts so it is necessary to do this work while in the larval stage.)
Downy Woodpeckers (and Black-capped Chickadees) have discovered this abundant source of winter food, and dine on the larva after chiseling a hole into the gall. Downy Woodpeckers tend to make a tidy,narrow, conical hole by pecking, while Black-capped Chickadees tend to make a messy, large, irregular hole by grabbing bits of the gall with their bill and tugging them free. While woodpeckers prefer larger galls that are located high on goldenrod plants growing near wooded areas, these are not the only factors taken into consideration.
A woodpecker extracts the fly larva through the tunnel the larva excavates prior to pupating, as this facilitates rapid removal of the larva. Downy Woodpeckers can determine whether or not a gall has an exit tunnel, and if it doesn’t, they usually abandon the gall without drilling into it. The likelihood of smaller parasitic wasp larvae occupying the gall (and a plump fly larva not being present) is much greater if there is no exit tunnel, and these smaller prey apparently are not always worth the woodpecker’s time or energy.
NB: Correction: this week’s Mystery Photo was of a Gray Birch (Betula populifolia) bract, not a Paper, or White, Birch (Betula papyrifera) bract. While similar, there are differences between these two species of birch that I should have recognized (especially when looking at the leaf!). Thanks to Kathy, an alert blog reader, who caught this error.
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Paper Birch Catkins: Winged Nutlets & Bracts Dispersing
Paper birch (Betula papyrifera) produces separate male and female flowers on the same tree, both in the form of catkins (cylindrical clusters of flowers). The catkins form in the fall and overwinter in a dormant state. In the spring they mature as the leaves develop, becoming pendulous. Male catkins are 2-4 inches long, whereas female catkins are usually 1 – 2 inches long. Both lack petals, enhancing wind pollination. After fertilization occurs, the male catkins wither away, while the female catkins droop downward and become cone-like.
The female catkins consist of tiny winged nutlets that are located behind three-lobed, hardened, modified leaves called bracts (yesterday’s blog post) and are usually dispersed by the wind during the fall and early winter. Birch bracts are species-specific — different species of birch have different-shaped bracts, allowing one to identify the species of birch that a bract comes from.
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Mystery Photo
Do you know what this is? If you do, do you know specifically what kind? Please post your response under “Comments” (before peaking at others’ responses!).
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Opportunisitic Bird Nest Builders
Several winters ago I discovered a Northern Mockingbird nest in downtown White River Junction, Vermont. Like all birds, mockingbirds are opportunists and utilize whatever material is available when building their nests. Even though it is not a booming metropolis (population roughly 2,500), White River’s relatively dense population is reflected in the building material that these songbirds used. Because they often nest in urban and suburban areas where trash tends to be more concentrated, mockingbirds often line their nests with bits of plastic, aluminum foil, and shredded cigarette filters (see photo). The male constructs the twig foundation while the female makes most of the lining. He often begins building several nests before the female chooses one to finish and lay eggs in.
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Rodent Incisors
Rodents have two pairs of incisors that oppose each other; two in the front of the upper jaw and two in the front of the lower jaw. These four teeth never stop growing, and thus have to be constantly filed down. (Squirrel incisors grow about one-half inch a month.) While nipping herbaceous plants and cutting into bark help do this, it isn’t enough to significantly wear down the teeth. When mice, beavers, woodchucks and other rodents nip or gnaw food, they move their jaws in such a way that these two pairs of teeth grind against each other. Most rodents have hard orange enamel on the outer side of their incisors (woodchucks are our only rodent with white enamel), and softer dentine in the back. When the incisors grind against each other, the dentine wears away faster than the enamel, creating a sharp, chisel-shaped edge to the incisors. This, more than anything else, keeps the growth of rodent incisors under control, just as a nail file keeps our nails from getting too long.
If a rodent breaks an incisor, there is nothing to wear down the opposing incisor. The tooth opposite the missing incisor will continue to grow unchecked in a circle until it causes the death of the rodent, either by piercing its skull or by preventing the animal from being able to eat. In the pictured woodchuck skull, the lower left incisor has broken off, allowing the upper left incisor to grow through the woodchuck’s palate and into its brain.
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Female Purple Finch or House Finch?
While the eastern population of Purple Finches has declined significantly since the invasion of House Finches (a few California individuals released from a pet store in New York City in 1939 as well as natural expansion of its western range resulted in a population explosion of House Finches in the east), both species can appear at feeders. Without fail, every winter I have to relearn the field marks that distinguish these two birds. Both males and females of these respective species are quite similar, but it is the drab and sparrow-like females that send me flying to a field guide.
Three features stand out as most helpful in distinguishing female Purple Finches from House Finches. The female Purple Finch has short, dark streaks on her breast, whereas the House Finch’s breast streaks are quite blurry. The female (and male) Purple Finch has a distinctly notched tail; the House Finch’s tail is just slightly notched. Finally, and most obvious, are their respective head patterns. Female Purple Finches have a conspicuous light eyebrow stripe that contrasts with a solid, dark brown ear patch, both of which the House Finch lacks.
Being seed eaters, Purple Finches are attracted to sunflower seed feeders, and if you feed birds, this provides ample opportunity to observe these field marks. While doing so, you may notice that Purple Finches can be fairly aggressive with each other when vying for this source of food. Surprisingly, more often than not, the female prevails. (photo: female Purple Finch)
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Maidenhair Spleenwort Greening Up the Woods
Five species of spleenworts (genus Asplenium) can be found in New England. Most of these small, native, evergreen ferns are found growing among rocks or on cliff faces. The Greeks believed that a species of spleenwort was useful for treating diseases of the spleen. The genus name Asplenium is derived from the Greek word for spleen (splen).
Maidenhair Spleenwort (Asplenium trichomanes) is divided into two subspecies, one that grows in crevices of acidic rocks and one that grows on more basic (alkaline) rocks. It grows in tufts and has long (three to six inches), delicate fronds made up of short, round leaflets paired from the central dark reddish-brown stem (stipe and rachis). If in doubt as to whether or not a spleenwort is Maidenhair, examine the stipe and rachis with a hand lens; if there is a narrow wing running the length of the fern frond, it is A. trichomanes.
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