While getting the mail at twilight recently, I was treated to a rare sight…a Bobcat (Lynx rufus)! It crossed the middle of the road about 25 yards (23 meters) away and stopped to stare at me. I heard cars approaching and didn’t want it to be hit, so I walked briskly toward the cat and it ran off into the woods. Some cats have learned to look both ways before crossing roads. Even so, car strikes are one of the leading causes of Bobcat mortality.

During the 1800s, Bobcats were rarely seen. Populations were probably quite low because of the widespread clearing of New England forests for sheep farms and charcoal production. Connecticut had a state bounty on these cats until as recently as 1971, but hunting and trapping seasons were discontinued over concerns that the species was facing extirpation. In 1972 the Bobcat was listed in Connecticut as a protected furbearer. As the forests grew back and hunting pressure abated, Bobcat populations have gradually rebounded.

Bobcats are medium-sized, stout-bodied felines about two to three times the size of a domestic cat. Males usually weigh from 18 to 35 pounds (8 to 16 kilograms) and are 32 to 37 inches (81 to 94 centimeters) long. Females are smaller at 15 to 30 pounds (7 to 14 kilograms) and 28 to 32 inches (71 to 81 centimeters) long. These cats are gray to tan on their sides, with faint black spots. Bobcats are named for their short “bobbed” tail.

Bobcats are polygamous (have more than one mate) and do not form lasting pair bonds. They mate in February and March and females raise the young, giving birth to one to four kits in April. Dens are located under fallen trees, in caves, on ledges, and in hollow logs.

For the past few years, Connecticut Department of Energy and Environmental Protection wildlife biologists have been studying Bobcats using radio telemetry. Cats are trapped, anesthetized, and fitted with GPS collars. Biologists had questions about Bobcat movement and home ranges as well as food preferences—and have discovered some surprising things. One female made a den next to an interstate. Bobcats are often hunting in woods near houses, but are so quiet that they are rarely seen.

By examining the stomach contents of road-killed animals, Connecticut DEEP biologists have found that Bobcats prey mostly on the Cottontail Rabbit (Sylvilagus floridanus), Eastern Gray Squirrel (Sciurus carolinensis), and American Red Squirrel (Tamiasciurus hudsonicus). Bobcats also hunt woodchucks, chipmunks, mice, voles, White-tailed Deer (Odocoileus virginianus—usually old, sick, or young animals), birds, insects, and reptiles. On occasion, they may also take small livestock and poultry, as well as unsupervised house cats. Other than making them potential Bobcat prey, it is never a good idea to let pet cats roam outside where they can contract the deadly feline leukemia virus. In the United States, free-roaming domestic cats kill up to 3.7 billion songbirds each year. Do Bobcats attack humans? Attacks on people are extremely uncommon and Bobcats rarely carry rabies. Bobcats should not be harmed.

In the last few years more people have reported Bobcat sightings. Despite increased development, populations in Connecticut now seem to be holding their own. Bobcats are very adaptable to living in a variety of habitats. They like mixed hardwood–coniferous forests, but seem to prefer younger forests with wetlands and brushy areas, or brushy woodlands with nearby fields.

Increasing urbanization, however, is fragmenting habitats. Bobcats in New England have a home range of 8 to 20 square miles (20 to 52 square kilometers). But animals in these fragments often are the most restricted in their movements, resulting in reduced natural genetic diversity. Preserving open space and providing wildlife corridors that connect available habitats are key to having these majestic animals with us for generations to come.

I am a light sleeper. I was awakened before dawn the other day by a pair of Great Horned Owls (Bubo virginianus) serenading in a large spruce tree outside my window. The male’s deep, resonant but soft “whoo who-who-who whoooooo whoooooo” was immediately followed by the female’s slightly higher call, and they continued back and forth. It’s courting time for this species and now is a good time to hear them. You might need to wake early though as they seem to be most vocal between 3 and 6 am—although I have also heard them at dusk along the Farmington Canal Trail in Hamden.

Male Great Horned Owls set up territories in October. During courtship and before mating, the male will display in front of the female and bring her food. These owls are usually monogamous and often mate for life. After raising young, however, the pair may roost separately until the following winter although still in the same territory.

The pair won’t build their own nest from scratch. Here in New England these owls will commonly use old nests made by Red-tailed Hawks (Buteo jamaicensis), American Crows (Corvus brachyrhynchos), and even Eastern Gray Squirrels (Sciurus carolinensis). Females usually do the incubating. In Connecticut, a female Great Horned Owl sits on two to five eggs for 28 to 35 days, as early as late January to early February. Research has shown that females can successfully incubate eggs even when temperatures hit –27 °F (–32.8 °C)!

Why nest in the cold depths of winter, which seems to be such a hardship? The Great Horned Owl is such a large bird that nesting early gives it a head start on lots of food for growing owlets in early spring right when prey is more active. It also gives young enough time to learn to hunt before the next winter.

This nocturnal owl is such an efficient predator that it is called “the tiger of the skies.” With adaptations like fringed feathers on its primaries, a wing span up to five feet (1.5 meters), extremely strong talons, incredible hearing, and large eyes with sharp vision in low light, it can fly almost silently and dive down on prey. Its eyes are among the largest of all terrestrial vertebrates, about the size of those of humans. They feed on a wide variety of prey, including small mammals such as rodents, hares, and rabbits, other owls, waterfowl, and marsh birds. And they are one of the few predators of the Striped Skunk (Mephitis mephitis).

The name “Great Horned Owl” is a misnomer. They don’t have horns. What they do have are actually large feather tufts. These feathers can indicate their disposition. When the Great Horned Owl roosts during the day, the tufts are often in a narrow, elongated position with upright feathers, a camouflage adaptation that looks like a branch. This might keep the owl from being detected by crows. Crows mob owls, as owls have been known to eat crows. When I see a murder of crows flying quickly in circles and calling excitedly with harsh “caws,” I know they’ve found a predator, usually a hawk or owl.

Great Horned Owls are found throughout North America, from the subarctic in Canada and Alaska down to Mexico. They are highly adaptable to a variety of habitats, from deciduous, coniferous, and mixed forest, to prairies, mountainous areas, rocky coasts, and mangrove swamp forests, to urban areas. If you’re lucky enough to hear them at this time of year, you’ll know they are likely courting. When much of the natural world around us seems dormant, it’s pleasant to think of new life poised to begin anew.

Many people associate the call of peepers, the smallest frog in Connecticut, with the arrival of spring. Recently, while hiking on a warm fall day, I heard the “peeping” of Spring Peepers (Pseudacris crucifer). It wasn’t the huge chorus you usually hear at vernal pools and shallow ponds in March and April. It was just a few individuals calling back and forth. Instead of at the water’s edge, the sounds were coming from under the leaf litter. Why call in the fall, when it is not the mating season? Are these a different species?

I also checked out a vernal pool where I know Wood Frogs (Rana sylvatica) call in spring. There was actually a small chorus of them “quacking” in the leaf litter near the water. What’s going on?

Spring Peepers, and sometimes Wood Frogs, can actually be heard calling in the fall. The Spring Peeper’s autumn calls sound a bit harsher and more abbreviated, with less of the sleigh bell-like chorus that you hear in the spring. Lang Elliot, a biologist who has recorded many sounds in nature, captured the calls of fall peepers.

Both Spring Peepers and Wood Frogs are getting ready to go into a very deep sleep called torpor. Their bodily functions slow down and they go into a near-death-like state—part of their bodies actually freeze! Although the spaces between their cells can freeze, they prevent their cells from freezing by producing glucose, thereby keeping vital organs alive.

There are several hypotheses as to why these frogs are calling in autumn, but one has to do with environmental conditions. The shortness of the days, lower angle of the sun, increasing rainfall, and cooler temperatures are very similar to spring conditions when these frogs become active. Some may be responding to these environmental cues.

I asked frog biologist David Skelly, director of the Yale Peabody Museum of Natural History and Frank R. Oastler Professor of Ecology at Yale, about it. He said in autumn, the weather can be like the spring breeding period. “These environmental cues may prod them into calling, since they undergo physiological changes during late summer and fall that will enable them to breed as soon as they become active after a long period of dormancy.”

The name Spring Peeper is not a misnomer. Peepers are a sure sign of spring. But you may also hear them and their Wood Frog cousins in the autumn months as these tiny creatures get ready to launch themselves into the mating game.

Leaves are fading to shades of brown and gray and dropping fast in the late fall winds as I walk along a local trail. At this time of year, I am always surprised when I come across a flash of bright yellow from the last native flowering plant of the year: the native American Witch-Hazel (Hamamelis virginiana). It’s a 20- to 30-foot (6- to 10-meter) small tree or shrub with crinkly, bright yellow ribbon-like petals that are often found among the medium-yellow autumn foliage. The flowers will last even after its leaves turn brown and fall off. Witch-Hazel blooms from September through November.

I have often wondered… what could pollinate a flower so late in the season, when all other flowers have  faded and the weather can be quite cold? Late-flying bees and parasitic wasps have been suggested, but biologist Bernd Heinrich discovered that a few species in the Owlet Moth family (Noctuidae) feed on the tree sap as well as nectar from the fragrant flowers of Witch-Hazel. How do they do it? They shake. By shivering its flight muscles, this moth can raise its temperature by 50°F (27.8°C) above the air temperature! And owlet moths are active at night, when they warm their bodies to 86°F (30°C) to be able to fly. They will lose this heat quickly, so they need to stop often to shiver again.

There are two other natives—Ozark Witch-Hazel (Hamamelis vernalis) and Big-Leaf Witch-Hazel (Hamamelis ovalis)—and two non-native witch-hazels—the Chinese Witch-Hazel (Hamamelis mollis) and Japanese Witch-Hazel (Hamamelis japonica). Unlike our native witch-hazels, these non-native species bloom in late winter and early spring. There are several hybrids of early, yellow-, orange-, or red-blooming cultivars of these.

The origin of the name Witch-Hazel is the Old English wice, meaning “bendable.” This may refer to the plant’s curved branching or that its branches are used by dowsers to find water, which was common until the beginning of the twentieth century. A dowsing rod allegedly points downward to water underground. The name “hazel” comes from the resemblance of Witch-Hazel fruit to the fruit of the unrelated American Hazelnut (Corylus americana).

The fruit of American Witch-Hazel is a two-part, greenish seed capsule that becomes woody. It takes eight months to one year for fruits to ripen. When this plant releases its seeds, it does it in a spectacular way. The outer layer of the ripe fruit both shrinks and expands, constricting the middle section, and forcing the seeds out with an audible snap or crack at more than 32 feet (10 meters) per second! Witch-Hazel is also called “Snapping Hazel” because of this. A ridge in the fruit’s inner chamber causes the seed when “fired” to spin like a bullet up to 430 times per second. The fruit can send the seed up to 30 feet (10 meters) away, an evolutionary advantage to reach potentially improved growing conditions.

According to entomologist Doug Tallamy, there are 60 species of butterflies and moths that feed on Witch-Hazel leaves. Ruffed Grouse, Northern Bob-White, Wild Turkeys, Eastern Gray Squirrels, and Eastern Cottontail Rabbits all eat Witch-Hazel fruit.

American Witch-Hazel is also useful to people. Native Americans used extracts from the branches and leaves medicinally, such as boiling the stems to make a decoction to treat swelling and inflammation. Early settlers in New England adopted these practices and use became widely established.

Missionary Dr. Charles Hawes learned of Witch-Hazel’s therapeutic properties and created his own extract by steam distillation of the twigs and bark. “Hawes Extract” was first produced and sold in Essex, Connecticut, by druggist Alvan Whittemore in 1846.

Thomas Newton Dickinson, Sr., refined Hawes’s process and is credited with the first commercial production of Witch-Hazel extract, also in Essex, Connecticut, in 1866. After his death his two sons, Thomas N. Dickinson, Jr., and Everett E. Dickinson, continued the family business with competing “Dickinson’s” businesses in different towns.

Eventually, the two companies came under the same corporate ownership. Today, Dickinson Brands still sells Witch-Hazel under the T. N. Dickinson and Dickinson’s labels. Witch-Hazel extract is used as an astringent to remove oils and impurities from the skin and also as an eye wash. Many people swear by it. Clearly there is more to Witch-Hazel than meets the eye. From its lovely delicate flowers that bloom when few flowers are still around, to its unique seed dispersal, to its long history as a useful plant to humans, the remarkable Witch-Hazel has much to recommend it.

We often think of migration as long-distance treks by birds, mammals, and fish traveling to wintering or nesting grounds. Animal migrations, however, can be short. They can even happen right in your own yard or neighborhood. Right now, Banded Woolly Bear caterpillars (Pyrrharctia isabella) are on the move to find places to overwinter, such as under a log or in leaf litter. You can see them crawling around in many different habitats. Taking a walk around the neighborhood recently, I spotted quite a few and helped them cross the road.

The Woolly Bear caterpillar is the larva of the Isabella Tiger Moth. They are found throughout most of the United States, Canada, and Mexico. These two-inch (5 cm) caterpillars are usually black on the ends and brown in the middle. If you have never touched a Woolly Bear, they don’t actually feel like wool. They are covered with 13 rows of soft bristles called setae.

There is some weather folklore associated with Woolly Bears. You might have heard that if the caterpillars have a wide brown middle band, it will be a mild winter. Or if the black bands at the end are wide and the middle brown band is narrow, expect cold and snow and a more severe winter. In reality, differing band length is partly due to genetics and how mature the caterpillar is, as the brown bands tend to widen with age. Research suggests wetter weather can also widen the black bands.

Other lore has to do with direction. If the caterpillar is traveling south, expect a harsh winter. If it is going north, winter will be mild. I’m not sure about east or west though!

Woolly Bear larvae have been found as far north as the Arctic, where temperatures can reach minus 90°F (–68°C)! These larvae are amazingly adapted to get through harsh winters—their bodies produce a cryoprotectant, an anti-freeze with glycerol, that keeps cells from freezing. The caterpillar’s setae also protect it from fluctuating winter temperatures. When spring temperatures rise to 50°F (10°C), the larvae will spin cocoons and a few weeks later pupate into adults.

In Connecticut, there are two broods of Woolly Bears. The first brood ecloses, or hatches, from cocoons and emerges as adult Isabella Tiger Moths in mid-summer. The second brood overwinters as larvae to pupate in the spring. Female moths put out a scent to attract males and after mating will lay batches of 100 or more eggs. The eggs hatch four to five days later. Woolly Bear larvae are generalist feeders and eat a variety of herbaceous plants, shrubs, and trees.

Next time you see a Woolly Bear caterpillar, you can thank yourself for leaving leaves and logs in your yard to help them to get through the winter.

Retirees who want to escape the cold and ice to spend the winter down south are known as “snowbirds.” Actually, this nickname describes the Dark-eyed Junco (Junco hyemalis). Juncos are arriving here now after spending the summer nesting in the mountains of New England and in the Canadian Boreal Forest. They will head back north next spring. In winter they feed on seeds of plants many of us consider “weeds,” including Chickweed (Stellaria media), Lambsquarters (Chenopodium album), and Wood Sorrel (Oxalis stricta). You will also see juncos at feeders. With their slate-gray backs and upper bellies, and white outer tail feathers that flash as they fly away, they are easy to spot.

The smallest bird of the winter woods, not much larger than a Ruby-throated Hummingbird (Archilochus colubris), is the Golden-crowned Kinglet (Regulus satrapa). This species spends the summer nesting in northern coniferous forests but lives in a variety of forest habitats here in winter. I’ve even seen it flitting among the oaks growing along New Haven streets. Being so small, it is in constant motion, continually foraging for wintering insects and their eggs among bark and branches to fuel its metabolism. It would starve if it could not find food for a few hours on a cold day. Listen for its call, a high-pitched “tseet-tseet-tseet,” as it feeds.

White-throated Sparrows (Zonotrichia albicollis) are arriving now. You can tell this bird from other sparrows by its black and white (sometimes tan) striped head and white throat. Look for them on the ground in woods and brushy edges. They can also be easily identified by their loud “chink” call. The White-throated Sparrow is one of the few birds that sings during the winter. Listen for its plaintive “Old-Sam-Peabody-Peabody” song. You will see both Dark-eyed Juncos and White-throated Sparrows on the ground under your bird feeders.

Some bird species that usually stay north in the winter will fly south during an irruption, a mass movement to another location that occurs periodically. An irruption is happening this year for some of these boreal migrants. Rather than being due to cold temperatures, this movement is actually tied to food availability. When the fruit and seeds of spruces, pines, mountain ash, and other trees are scarce in the north, some birds seek food elsewhere. The Winter Finch Forecast (maintained for decades by biologist Ron Pittaway, who recently passed the torch to Tyler Hoar) uses reports from foresters, researchers, naturalists, and other observers about the northern tree seed crop to predict which bird species will fly south or west.

Boreal migrants spotted at feeders here recently confirm this forecast: the Purple Finch (Haemorhous purpureus), Pine Siskin (Spinus pinus), and another migrant (not a finch), the Red-breasted Nuthatch (Sitta canadensis).

You can tell a male Purple Finch from the more common male House Finch (Haemorhous mexicanus) by the deeper color on the Purple Finch’s head and upper back—it looks as if it was dipped in raspberry juice. The male House Finch’s more reddish head color does not extend down its back. Purple Finches like to eat black oil seed at feeders.

Red-breasted Nuthatches travel in mixed flocks with Black-capped Chickadees (Poecile atricapillus), Downy Woodpeckers (Picoides pubescens), and Golden-crowned Kinglets. Unlike the larger, resident White-breasted Nuthatch (Sitta carolinensis), the Red-breasted Nuthatch has a reddish belly and black eye stripe. Its call is more nasal and higher pitched. Both species are called “upside-down birds,” as they often walk down a tree’s bark hunting for insects. They will take sunflower seeds, peanuts, and suet at feeders.

Pine Siskins are very gregarious and often travel and feed in flocks. This brown, streaked bird with yellow on the edges of its wings and tail is better identified by its harsh, ascending “zrweeet” call. If they are around, you will see them at thistle feeders.

Not every Blue Jay (Cyanocitta cristata) that you will see this winter is a permanent resident here. About a quarter of Blue Jays are migrants from northern climes. At this time of year, I often see them flying over highways as they migrate.

It’s a great time of year to observe these colorful visitors from the north. Put out a bird feeder or two and enjoy them.

If you’ve ever had to remove burrs from your pants after a hike or from your dog’s ear after a walk, you know what I’m talking about. The different ways plants have evolved for dispersing their fruits and seeds are truly remarkable. All for the sake of reproducing their species, seeds are adapted in different ways to travel by land, air, and sea—and in some cases, to even launch themselves on their own incredible journey through the digestive tracts of birds and other animals.

There are several ways seeds are dispersed: by hitchhiking on fur or clothing; by becoming airborne; by exploding from pods; by being carried in water; by being digested by birds, fish, and other animals; and by being buried.

While walking along the edge of my property a few days ago, I brushed up against some plants and found several “hitchhikers” attached to my jeans. They were Stick-tights (Desmodium cuspidatum). Their small, flat, green triangular seeds, which have tiny hooks that attach to the fur of many mammals, eventually find a new place to germinate. Devil’s Beggar-ticks (Bidens frondosa), with its two-pronged hooks, is another hitchhiker.

We all have blown the ripe seeds of Dandelion (Taraxacum officinale) or thrown the ripe seeds from milkweed pods to watch them float away. A “parachute” attached to your seed can certainly spread you far. Other seeds have wings that act like whirligigs or helicopters, such as the double-winged samaras of maples (Acer spp.) that spin to get away from the parent tree and hopefully finding good ground in which to germinate. There is a seed attached to each wing.

Researchers have documented incredible long-distance dispersals of plants and fungi on the feathers of birds. Microscopic spores of mosses, liverworts, and fungi have been found on the primary feathers of three bird species: Semi-palmated Plover (Charadrius semipalmatus), Red Phalarope (Phalaropus fulicarius), and American Golden-Plover (Pluvialis dominica). These birds migrate from the Arctic to South America. Those spores were still alive when the birds arrived at their destinations. When the birds molt their feathers the spores contact the ground and germinate.

Native to Connecticut, Jewelweed, also called Touch-Me-Not (Impatiens capensis), has a more explosive tendency. As the fruits dry out, mechanical energy stored in valves in the fruits cause them to coil inward, collapse the fruit pods, and eject the seeds. If you touch the slender seed pods, which are ripe now, you will see the seeds explode out of the pods, sometimes traveling up to 8 feet (2.5 meters) or more. Jewelweed spreads easily as a result. And it’s a good thing, because the flowers are an important source of nectar for migrating hummingbirds. The ripe white berries of dwarf mistletoes (Arceuthobium spp.), native to the western United States and Canada, also explode, ejecting seeds at an average speed of 60 miles (96.5 kilometers) per hour and scattering them as far as 50 feet (about 15 meters). The Eastern Mistletoe (Phoradendron leucarpum), native to southern North America is not nearly so dramatic. Its seeds are dispersed when birds eat its fruit, leave seeds in droppings and also wipe the sticky seeds from their bills on tree branches, where they can germinate.

The seed of the Coconut Palm (Cocos nucifera) can float in saltwater for up to a year before seeding itself on a southern sandy shore. The “seeds” of the Red Mangrove (Rhizophora mangle) actually germinate and become seedling propagules before dropping off the parent tree. They are dispersed by water and eventually embed themselves in the shallows.

There is a well-known relationship between the Yellow-rumped Warbler (Dendroica petechia) and the flowering shrub Small Bayberry or Wax Myrtle (Morella caroliniensis). When these warblers eat these berries, the birds’ gizzards scarify the seeds and their droppings help to fertilize them, ensuring germination. These birds were once called Myrtle Warblers.

Other seeds such as acorns rely on animals like squirrels, chipmunks, and even crows to bury them. If the animal does not return to its stash, the seeds may germinate. To attract wildlife, plants like blackberries and raspberries surround their seeds with a brightly colored and sweet tasting pulp. Even ants get into the act. The seeds of the spring wildflower Bloodroot (Sanguinaria canadensis) have elaiosomes, fatty attachments that attract ants. The ants will carry seeds to their nest and eat the elaiosomes. The seeds then have a fertile place to germinate.

Why do these seed dispersal adaptations exist? There are several reasons. Often, the survival rate of a seed improves away from the parent plant, because it competes less with the parent and, in cases where predators are attracted to a clump of newly germinated plants clustered around a parent plant, it is less likely to be eaten. These adaptations allow plants to reach specific habitats that are more favorable for survival, a hypothesis known as directed dispersal. Adaptations that favor dispersal on a more distant scale allow plants to colonize new and vacant habitats or regions, reducing a plant’s risk of predation and increasing its chances for survival.

So, the next time you spy a Jewelweed “popper” go ahead, give it a pinch and watch those seeds fly! You’ll be helping seeds do what they were meant to do—and besides, it’s fun.

Look up! It’s happening right now, right over your head. It’s the autumnal migration of raptors—hawks in particular. And it is one of nature’s most impressive animal migrations.

When I was a child, I asked my mom to take me to Hawk Mountain. It was a two-hour drive from where we lived in northern New Jersey to Kempton, Pennsylvania, but she was determined to help fuel my passion for nature and off we went. It was a sunny early November day when we arrived at the North Lookout. Just as we got there a Golden Eagle (Aquila chrysaetos) flew by us at eye level. The sun lit its seven foot wingspan as if it was on fire. I’ve been hooked on hawks ever since. Every year I watch for them as they pass through our area.

Hawks, falcons, ospreys and vultures can be seen migrating here from the end of August through mid-December, although the greatest diversity of species can be seen now through the end of the month. The birds take advantage of warm, spiraling air currents called thermals, which allow them to rise thousands of feet. They “hop scotch” south, gliding from one thermal to the next. There are two migration paths or flyways these raptors tend to follow in Connecticut. They catch updrafts and thermals along the Northwest Hills and use thermals to follow the coastline. Some Ospreys (Pandion haliaetus) and Peregrine Falcons (Falco peregrinus) bypass the land routes south and fly across the Atlantic instead. These birds are heading to the northern South American coast.

Weather can really influence raptor flight on any given day. The best conditions occur on certain kinds of days, such as after a cold front passes through, and on days with northwesterly winds. On a windy day they fly from dawn to dusk.

Although in good conditions you might see hawks overhead anywhere, there are some great viewing hotspots in Connecticut. One of the best is Lighthouse Point Park in New Haven. Quaker Ridge Hawk Watch at Greenwich Audubon is another great site. Other places to watch are included here.

Many of North America’s fall raptor migratory routes converge at Veracruz, Mexico. There a small section of coastal plain is constricted between the mountains of the Sierra Madre and the Gulf of Mexico. At two raptor watching sites counts can top 100,000 birds in one day! It is the greatest raptor flyway in the world.

There are various tricks to identifying hawks, falcons, ospreys, and vultures in flight. The Cornell Laboratory of Ornithology’s All About Birds is a great site for identification. To test your knowledge, you can try a quiz.

Now’s the time to see this amazing wildlife spectacle. The next time a cold front passes through or winds blow from the northwest, grab your binoculars and look up.

They’re changing now.

It’s that time here in Connecticut when deciduous trees change color and add drama to our forests and landscapes. Most of the colors we see in beautiful autumn foliage have been there all along. As day length and temperature decrease, the cells between the leaf and the petiole (stem) develop a corky abscission (separation) layer that begins to block materials coming into and going out of the leaf. As a result, leaves stop making new chlorophyll (the green pigment that makes energy for the plant using sunlight, carbon dioxide, and water) and their green color fades. The leaf’s yellow and orange pigments, called carotenoids, then show through. Yellow leaves from trees such as Witch Hazel (Hamamelis virginiana) are a good example.

Some pigments are produced later by chemical changes and weren’t there all along. Anthocyanins give rise to the brilliant reds in the Sugar Maple (Acer saccharum), Sumac (Rhus spp.), and Northern Red Oak (Quercus rubra) and to the red-purplish color in Flowering Dogwood (Benthamidia florida).

Weather certainly affects the intensity of colors. The drought we have been experiencing has stressed our trees. Some lost their leaves early or started turning color prematurely. So fall foliage will not be as vibrant. Adequate summer rains promote healthy trees that hold onto their leaves longer and thereby have richer autumn colors.

The right fall weather can cause anthocyanins to produce vibrant reds. This pigment needs sunlight for color production and the colors are enhanced by sunny days and cool nights. This is why fall color is so outstanding in the colder climes of Vermont and other areas of northern New England.

Owen Reiser, a biology and mathematics student from Southern Illinois University, filmed leaf color changes using time-lapse photography.

The purpose of leaf color is still shrouded in mystery, especially for the anthocyanins. Researchers have proposed various hypotheses. A physiological explanation is that anthocyanins act like a sunscreen, allowing the tree to better reabsorb nitrogen as chlorophyll is broken down. Nitrogen helps the plant in the next growing season. There is evidence is that redder leaves have less nitrogen when they fall from the trees, compared with leaves without anthocyanins.

One biological explanation is that color is camouflage for leaves to keep them from being recognized and eaten. Or the bright leaf colors may be an adaptation to dissuade insects from laying eggs if they think the leaves are toxic, thereby minimizing damage to the plant the following year. Another possible explanation is that bright colors are a flag to draw animals to eat the fruit and so disperse seeds away from the tree. Poison Ivy (Toxicodendron radicans) is thought to be an example of this—its bright red leaves in the fall may be a signal to birds that the plant’s white berries are ripe.

Rather than raking, bagging, and putting your leaves to the curb, put them to good use. Remember that leaves make an outstanding mulch under your trees and shrubs and create important overwintering sites for native moths that provide food for birds for next year’s nesting season. You can easily make a leaf mulch container by a bending a four-foot (1.2 meter) high section of hardware cloth into a large circle supported with two stakes. Fill it with your leaves and by next summer or fall you’ll have an excellent mulch to add to your garden beds through the growing season.

Happy leaf peeping.