Turtle Talk

If you are silent and slow as you approach Rainbow Bridge to cross over Lake Wapalanne, you may be lucky enough to see a group of Eastern Painted Turtles basking on a fallen pine tree that rests, half submerged, in the water.  These turtles, which do not exceed ten inches in length, discovered this basking spot as soon as the warm spring months arrived.  After a winter of hibernating underwater in the cold mud of Lake Wapalanne, their sunny perch is a welcome resting place.  It is fitting that these turtles can be seen from Rainbow Bridge, because they are very colorful turtles, named for the yellow, olive, or red borders along the shell; orange and red marks on the edges of the shell; yellow underside; and red, orange, and yellow markings on the neck, legs, tail, and face. 

Painted turtles, like all turtles, are reptiles, herpetons, or “crawling things.”  They belong to the order Chelonia.  There are three additional orders of reptiles, including the Squamata, or lizards and snakes, Crocodilia, and Rhynchocephalia, which contains only one living genus.  Turtles evolved from the ancestor Eunotosaurus africanus, a small animal that lived in South Africa about 260 million years ago.  This animal began to develop large, thick ribs, which preceded the formation of the turtle’s carapace, or shell.  248 million years ago, Anthodon was a reptile that developed bony, plated armor, much like the turtle’s shell today.  However, the animal that is considered to be the ancestor of all modern turtles and tortoises is Proganochelys, which lived 220-230 million years ago.

There are more than 300 species of turtles worldwide today, and each is characterized by its carapace, or the top of the shell; plastron, or the part of the shell that covers the underside of the turtle and is fused to the ribs; and the two lateral bridges, which are ligamentous tissues that connect the carapace and plastron on either side of the turtle.  Some turtles are known as soft-shelled turtles, and these turtles, instead of having a typical carapace made up of bony plates, actually have a continuous covering of leathery skin on top of the bones that make up the shell.

The turtle’s bony shell is a calcified structure.  It is covered with a thin layer of keratinous scales, or scutes, which are made up of the same material as our fingernails.  Just as a snake sheds its skin, the turtle will shed its scutes.  If a turtle’s shell is injured, it has the capacity to repair itself.  The underlying tissue will calcify and the keratin will reform.  This, however, may take a long time.  Often, the scutes on a turtle’s shell match the substrate of the environment in which the turtle lives.  This camouflage often provides them with great protection.

Turtles, like all reptiles, are cold-blooded creatures; they need to absorb heat from their environment to stay warm.  To deal with the cold, turtles have many strategies.  Heat generated from muscular activity, insulation from fat, and the protection from the carapace all allow the turtle to stay warm.  Additionally, turtles may stay warm by covering themselves with mud, water, sand, or urine.  In the winter, turtles hibernate to survive the cold months.  When it is too hot, turtles will burrow, take mud or sand baths, and slow their metabolisms to stay cool.

Turtles have no teeth; instead, they have a beak.  They have internal ears that give them excellent hearing.  Turtles are very sensitive to ground vibrations, so they are difficult to sneak up on, even if you are being extremely quiet.  This is why the Painted Turtles will plunge into the water as soon as you walk by!  Turtles have a poor sense of smell and poor eyesight; they react more to movement than to shapes.  Their heartbeats are much slower than ours, beating at just about 20 times per minute!

The smallest turtle is the 100mm long speckled tortoise of South Africa.  The largest turtle, the leatherback sea turtle, is 2 meters long!  Can you imagine swimming in the ocean with a turtle that big?  While turtles are often found in water, every species lays its eggs on land, including sea turtles.  All species of turtles are long-lived and can expect to live for half a century or more, with some exceeding 150 years!  Most turtles lay eggs that take between 60 and 100 days to incubate, depending on the species and the temperature of the sand or soil.  Of the 330 or so species of turtles, thirteen live in New Jersey, and eight live in Sussex County.  Those that live in other parts of the state include the Eastern Mud Turtle, Northern Diamondback Terrapin, Common Map Turtle, Redbelly Turtle, and Eastern Spiny Softshell Turtle.

Of all of New Jersey’s turtles, perhaps the last one that we want to encounter is the Common Snapping Turtle.  Found swimming in ponds and lakes, lurking in aquatic vegetation, or basking just beneath the surface of the water, the Snapping Turtle is a turtle to avoid.  With a massive head, strong jaws, a sharp beak, and long claws, this turtle can cause injury to those who approach it too closely.  An omnivore, the Snapping Turtle has a varied diet and will eat insects, fish, worms, amphibians, snakes, other turtles, birds, small mammals, plants, and algae.  About thirty small Snapping Turtles will hatch from their eggs in late August through October; these babies may one day reach a size of more than 75 pounds!

Another turtle that can be found swimming in lakes and ponds is the Common Musk Turtle, also known as the Stinkpot Turtle.  This small turtle grows no bigger than five inches long.  It is given its name because of the foul smell the turtle exudes from its glands when it feels threatened, just as a skunk does.  This turtle will bask beneath the surface of the water and prefers to walk along the muddy bottom, where algae will grow on its shell.  Also an omnivore, the Musk Turtle eats small insects, algae, snails, fish eggs, and amphibians.

The Spotted Turtle is another small turtle, growing no more than five inches long.  This turtle has a black shell with small yellow spots; the turtle also has yellow spots on its head, neck, and limbs.  These spots break up the outline of the turtle, making it harder for potential predators to see it; the spots may also appear to be rays of sun reflecting on the surface of the water.  This turtle can be found in marshes, small creeks, and wet forested areas.  They are omnivores, feeding on insects, algae, aquatic vegetation, small amphibians, and freshwater crustaceans.

A turtle that we’d rather not see in New Jersey is the Red-eared Slider Turtle.  This species is native to the southeastern United States, but it has been introduced to New Jersey, and many other places, by pet owners who no longer want these turtles as pets.  These opportunistic turtles are recognized by a red band behind each eye.  Like the Painted Turtles, Red-eared Sliders love basking in the sun.  They are omnivores and eat snails, crayfish, insect larvae, tadpoles, small fish, and vegetation. Both Red-eared Sliders and Painted Turtles tend to be more carnivorous when they are born and eventually transition to a mostly herbivorous diet as adults.

 

The least aquatic of all of New Jersey’s turtles is the Eastern Box Turtle, which prefers upland, forested areas, though it will always be near a source of water.  The genus name for this turtle, Terrapene, comes from “terrapin,” a word by the Algonquian, a group of indigenous people who inhabited the northeastern United States.  Box Turtles are known for their high, domed shells that are fit with a hinged plastron; this hinge allows the turtle to close itself entirely within the shell to keep away from any threats.  Young Box Turtles eat insects, worms, slugs, and snails, while adults are more herbivorous, preferring mushrooms above all else.

 

 

Sadly, two thirds of the world’s turtle species are threatened or endangered today, due to a multitude of factors including the pet trade, zoo trade, and the desire for turtle shells and turtle-derived oil, meat, and fat.  New Jersey is home to one threatened species, the Wood Turtle, and one endangered species, the Bog Turtle.  The Wood Turtle was listed as a threatened species in 1979 after major decreases in its abundance and distribution across the state were recorded.  Habitat loss and stream degradation have impacted this riparian and wetland-loving turtle.  The small Bog Turtle, less than five inches long, is very elusive, but has become even harder to find due to habitat loss, pollution, and illegal collecting.  If you find a Bog Turtle in marshes, wet meadows, or fens, that habitat should be managed in favor of the Bog Turtles by controlling nonnative plant species and suppressing vegetative succession.

Here at the New Jersey School of Conservation, researchers from Montclair State University study the turtles found in Lake Wapalanne.  Dr. Lisa Hazard, Dr. Kirsten Monsen-Collar, and students Tara Snyder, Paola Dolcemascolo, and Linda Araya capture and mark Common Musk Turtles and Eastern Painted Turtles.  They take data on these turtles, including information on size, sex, and evidence of predation damage or parasites, before releasing them back into the lake.  Why take this preliminary data?  The researchers are hoping that gaining a sense of the population and the behavior of turtles will lead to more rigorous research questions.  Possible research projects for the future include exploring the effects of parasite loads, particularly leeches; understanding population dynamics, reproduction, and predation; and understanding the effects of people and other animals on turtle behavior.  By continuing to learn about turtles, conducting research, and preserving habitat that is vital for turtle survival, we can help protect New Jersey’s turtle species.

References:

Bonin, Franck, Bernard Devaux, and Alain Dupré. Turtles of the World. Baltimore: Johns Hopkins UP, 2006. Print.

Schwartz, Vicki, and David M. Golden. Field Guide to Reptiles and Amphibians of New Jersey. 1st ed. NJ Division of Fish and Wildlife, 2002. Print.

Admirable Admirals

Found all over North America, from Mexico to Canada, the red admiral butterfly (Vanessa atalanta) has invaded New Jersey during its annual migration north.  New Jersey’s mild winter has provided the perfect conditions for the population of this butterfly to explode.  Their brown wings, splotched with red-orange bands and tipped with white spots on a black backdrop, can be found perched all over the New Jersey School of Conservation, and visitors to the school recognize the butterflies from their own hometowns elsewhere in New Jersey.

 

These butterflies are so widespread that enormous populations are migrating through western New York, Michigan, and Minnesota right now.  In fact, the butterflies can survive on almost every continent; they are found on some Caribbean islands, in Central America, New Zealand, Europe, North Africa, and Asia.  The butterflies prefer moist woods and fields, marshes, and yards and parks.  During migration, they can be found in almost any habitat, including environments as different as the subtropics and the tundra.

About every ten years, the red admiral population booms.  The last great migration of these butterflies was in 2001, so we are due for this spring treat!  Experts believe that this year’s migration is even greater than those population explosions in 2001, 1990, and 1981.  To escape the winter, red admirals fly south every year to warmer places such as the Carolinas and Georgia.  Like the monarch butterfly, the red admirals lay eggs, then die, and more are born.  In the spring, the newly born butterflies begin to migrate north, arriving in northern states like New Jersey.  Because this year’s winter was so mild, the butterflies have had better luck reproducing and creating the brilliant red and orange migrations we are seeing this spring.

Red admirals have a two to three inch wingspan.  Adults eat sap flows on trees; bird droppings; nectar from common milkweed, red clover, aster, and alfalfa; some flowers; fermenting fruit; and other plant fluids.  Adult females lay their eggs on the top of host plants, particularly plants in the nettle family.  The caterpillars, who eat the leaves of the host plant, spend their time within the shelter of folded leaves, then in a nest of leaves tied together with silk, before emerging as adults.  Like the monarch butterflies, the red admirals will produce about three generations of butterflies in the southern states before the fourth generation migrates north in the spring.  It may be another decade before these beautiful butterflies flock north in such great numbers, so be on the lookout for these admirable admirals!

References:

Hutchins, Ryan. "A Banner Year for Butterflies." The Star-Ledger 11 May 2012. Print.

"Red Admiral (Vanessa Atalanta)." Butterflies and Moths of North America. Web. 11 May 2012. http://www.butterfliesandmoths.org/species/Vanessa-atalanta.

Every Drop Counts

In Sussex County, we live in a relatively water-rich region, receiving between 40 and 45 inches of precipitation each year.  With so much water—and many clean natural water sources, including the artesian wells that pump water from beneath the ground in Stokes State Forest—we sometimes don’t realize how much we take water for granted.  Water is the source of all life on earth, but our freshwater resources are depleting due to overuse and pollution.  In New Jersey, populations are increasing while water resources remain constant, creating a more stressful demand on our water supplies.

The average American uses approximately 100 gallons of water each day.  The average New Jersey resident uses approximately 70 gallons of water each day, but during the summer, this number jumps to 155 gallons of water each day.  However, these numbers only include water used in the home, for things like bathing, cooking, doing laundry, and flushing toilets.  These numbers don’t include the water used to produce the food that we eat or the energy that we use.  And less than 1% of Earth’s water is available for human use!  The rest is salt water in the oceans, frozen water locked up in icebergs and polar ice caps, or simply inaccessible or polluted water.

Many people in the world don’t have access to nearly the same amount of water as we do in the United States.  The average global citizen only uses approximately 2.5 gallons of water each day.  In many developing countries, this water is often unsafe to drink and too polluted for good hygiene.  Additionally, humans aren’t the only ones who depend on clean, safe water.  The plants and animals in our surrounding environment need this water as well. 

In school, we learn about the water cycle: evaporation and transpiration, condensation, precipitation, and collection or storage.  We know from the water cycle that water is recycled, that we can keep using it again and again.  However, the water cycle is not completely reliable.  Water doesn’t always return to the same places or in the same quantities.  Some of the water that returns to the earth through precipitation may be inaccessible for human use, or it may become polluted, depending on where it travels.  For all of these reasons, it is important to treat the water that is accessible to us—and other organisms—very carefully.  

You’d be surprised to learn just how much water we use to produce our foods and other materials.  About 70% of water worldwide is used for agriculture.  In the United States, the great Ogallala Aquifer, an underground freshwater source, is used to irrigate farms across the Great Plains.  However, the water supply in this aquifer is shrinking rapidly, and some people believe that the water will only last a mere 25 more years.  This isn’t very long at all, considering it takes approximately 40 gallons of water to produce an egg, 80 gallons of water to produce an ear of corn, 150 gallons of water to produce a loaf of bread, and 2,500 gallons of water to produce one pound of beef!  Additionally, it takes up to 25 gallons of water to produce one gallon of gasoline, 280 gallons of water to produce a Sunday newspaper, and 100,000 gallons of water to produce a new car!

There’s no way around it: as a society, we Americans use a lot of water.  Luckily, there are many simple things you can do to conserve water.  For starters, make sure you don’t leave the faucet dripping.  A dripping faucet can waste 20 gallons of water a day!  If you see a faucet dripping, try to turn it off, or ask somebody to fix it.  You can also turn off the water while you are brushing your teeth or soaping up your hands, and only use the water to rinse.  Similarly, if you are washing dishes by hand, don’t leave the water running while you do so; soap up first, then rinse them all at once.  If you are going to run the dishwasher or the washing machine, make sure you have a full load of dishes or laundry to make sure you are using the water as efficiently as possible.  Time yourself: take shorter showers.  And you don’t need to flush the toilet every time you use it.  If it’s yellow, let it mellow!  Keeping the lid of the toilet shut will help prevent the spread of bacteria or odors.

If you have pet fish, and you change the water in their tank, instead of dumping the water down the drain, use it to water your plants.  In the summer, the water collected from your dehumidifier can also be used to water the plants.  It’s more efficient to go to the car wash than to wash your car by hand.  If you want to wash your car at home, do it on the lawn, so the grass will benefit from the water as well!  Water your garden or lawn early in the morning or late in the evening, when the sun is not strong and will not evaporate too much water, and the plants will be able to use more of the water.

Finally, don’t use plastic water bottles.  Each year, 1.5 million barrels of crude oil are used for making plastic bottles.  That’s enough oil to power 100,000 American cars for a whole year!  And often, the water from a plastic bottle isn’t even as good as the water that comes out of your faucet.  For example, a four-year study by the National Resources Defense Council found that one-fifth of the 103 water products they tested contained synthetic organic chemicals.  Many bottled water companies just get the water straight from the tap, anyway!  Find a reusable water bottle and use it—again and again.  You’ll limit your waste and you’ll save water.  Remember that it takes 25 gallons of water to produce one gallon of gasoline.  Just imagine how much water is used to produce the 1.5 million barrels of crude oil used for making plastic bottles!  You’ll also be cutting your carbon footprint by eliminating the transportation associated with delivering bottled water to stores.

With a simple Google search online, you’ll be able to find hundreds and hundreds of tips about how to save water.  To start, try going to 100 Ways to Conserve or Water Conservation Tips.  Happy conserving!

References:

"100 Ways To Conserve." Water Conservation Tips, Facts and Resources. Water Use It Wisely. Web. 12 Apr. 2012. http://www.wateruseitwisely.com/100-ways-to-conserve/index.php.

"How to Go Green: Water." TreeHugger. 3 Dec. 2006. Web. 12 Apr. 2012. http://www.treehugger.com/htgg/how-to-go-green-water.html.

"New Jersey Water Fact Sheet." WaterSense. EPA, July 2010. Web. 12 Apr. 2012. http://www.epa.gov/watersense/docs/new_jersey_state_fact_sheet.pdf.

NJSOC Water Ecology Fact Sheet.

"Our Water." WaterSense. EPA. Web. 12 Apr. 2012. http://www.epa.gov/watersense/our_water/index.html.

"Water Conservation Tips." National Geographic. Web. 12 Apr. 2012. http://environment.nationalgeographic.com/environment/freshwater/water-conservation-tips/.

Diptera and Odonata and Ephemeroptera, oh my!

Students of Water Ecology at the New Jersey School of Conservation spend their class wading in the tributaries of the Big Flatbrook, outfitted in rubber boots, turning over river-worn rocks to look for the benthic macroinvertebrates that cling to the bottom of these stones.  A benthic macroinvertebrate is an organism that has no backbone, is visible to the naked eye, and lives on the bottom layer of a body of water, often in the sediment.  Most of the benthic macroinvertebrates that students find are actually the larvae of aquatic insects, those insects that live a portion of their life cycle in the water.  In order to become an adult, these aquatic insects undergo a metamorphosis and leave the water once their wings have dried.

Perhaps our least favorite aquatic insect is the mosquito, of which there are 2,500 different species worldwide and 150 species in the United States!  The mosquito, of the order Diptera, goes through four distinct life stages, three of which are spent in the water.  Adult mosquitoes lay eggs one at a time on the surface of the water or on damp soil that will become flooded by water.  Some species make egg rafts, where the eggs stick together and float on the water.  Within about 48 hours, these eggs will hatch into larvae.  The larvae, also known as “wigglers” or “wrigglers,” live in the water for one to two weeks.  They use a tube called a siphon to breathe oxygen at the surface of the water.  Eating micro-organisms and organic matter such as algae, the larvae go through four molts, during which they shed their skin and grow larger.  After the fourth molt, they become pupae and begin the final metamorphosis to adult mosquitoes.  The pupae, who do not feed, remain in the water for one to four more days, depending on the species of mosquito and the temperature of the water.  Lighter than water, the pupa floats at the surface and uses two breathing tubes called trumpets to receive oxygen.  Pupae are known as “tumblers” because when disturbed, they dive in a jerking, tumbling motion before floating back to the surface.  Within a pupal shell, the adult mosquito develops over a period of about two days.  Finally, the pupal skin will split and the adult mosquito emerges from the skin.  At this point, the adult will rest on the surface of the water, allowing its new body to dry and harden and its wings to spread.

Mosquito Larva

The adult male mosquito only lives for about a week, while the adult female mosquito lives for about a month.  However, temperature, humidity, and time of year also affect the lifespan of this insect pest.  If you find yourself sitting outside on a summer evening, slapping away at the mosquitoes biting your ankles, you are actually targeting only the females of the species!  Female mosquitoes depend on the protein in blood to produce their eggs.  The males, in contrast, only feed on flower nectar and other plant juices.  Humans aren’t the only ones that these ladies bite, however; cows, chickens, deer, rabbits, snakes, frogs, and many other types of animals also make up a tasty dinner menu.  If you’re worried about the mosquitoes being a problem in your yard this summer, make sure you eliminate any standing water; mosquitoes aren’t picky, so they will lay their eggs in any kind of water!  Keep in mind that mosquitoes make up an important part of the food chain, providing sustenance for many creatures, including bats, frogs, and fish.

Preferring cleaner water than the mosquito to lay their eggs, dragonflies and damselflies are aquatic insects that belong to the order Odonata, which means “toothed ones.”  They are called this because each dragonfly and damselfly has a prehensile labium, or extendable jaw, beneath the head; this jaw can extend faster than most prey can react.  This adaptation makes the bite of the Odonata fatal to its prey, which includes mayflies, caddisflies, gnats, ants, termites, and other small insects.  All six legs of the Odonata are located close to the head; rather than using their legs for walking, the legs are most often used to catch prey or to perch.

Dragonfly Larva

It is easy to tell the difference between dragonflies and damselflies.  Dragonflies have stout bodies and when resting, they extend their wings to each side.  The damselfly, in contrast, has a very slender body, and when resting, holds its wings together above the body.  Dragonflies and damselflies are additionally characterized by their eyes, which are very large in proportion to their heads.  Their eyes are so large that over 80% of brain power is devoted exclusively to analyzing visual information!  Odonata species have two pairs of long wings that are made strong and flexible by a strong crossvein and many small criss-crossing veins.  With these wings, dragonflies, who can fly faster than damselflies, ambulate forward at about 100 body-lengths per second, backward at about 3 body-lengths per second, or hover in the air for about a minute.  While most species have wingspans that are about 5 to 8 centimeters wide, 325 million-year-old fossils show that ancestors of dragonflies had wingspans up to 30 inches wide!  With exceptional sight and agile flight, dragonflies and damselflies may escape from their predators, which include birds, lizards, frogs, spiders, fish, water bugs, and even larger dragonflies.

 
Damselfly Larva

Like mosquitoes, dragonflies and damselflies spend a part of their lives in the water.  However, they only go through three distinct life stages.  Dragonflies lay round eggs in the water, while damselflies lay cylindrical, long eggs.  The larvae of the Odonata are known as “nymphs,” and most of the insects’ lives are spent in this stage.  While a mosquito molts only four times, the Odonata may molt six to fifteen times!  In order to breathe in the larval stage, nymphs expand and contract their abdomens to move water over their gills.  Depending on many factors, they may remain in the larval stage for up to six years.  While the mosquito enters into a pupal stage, dragonflies and damselflies will simply crawl out of the water, molt one final time, and emerge from their old skin as winged adults.  Because they skip the pupal stage, Odonata are known as “hemimetabolous,” or those who undergo an incomplete metamorphosis.  With a longer lifespan than mosquitoes, adult Odanata can live for up to six months under favorable conditions.

While dragonflies are more sensitive to pollution than damselflies, both are indicators of healthy ecosystems.  Many factors affect the distribution of nymphs, including acidity of water, the amount and type of aquatic vegetation, temperature, and the type of environment.  Cool streams, rivers, ponds, marshy areas, and still clear water are favorites of various species.  Did you know that the New Jersey School of Conservation is located in the Odonata capital of the country?  Sussex County has more species of Odonata than any other county in the country, tallying in at 145 species!  Due to its varied topography and geology, poorly drained swamps and marshes, and rich boreal habitat with plenty of clean rivers, lakes, and streams, dragonflies and damselflies love to call Sussex County home.

Even more sensitive to the environment than the Odonata are mayflies, members of the order Ephemeroptera.  Mayflies, of which there are 2,000 species, are the only insects to go through two flying stages in their metamorphosis.  Mayflies mate in swarms during calm weather before depositing their eggs, flying low over the water or dipping their abdomens on the surface.  Some adults even submerge themselves and lay their eggs underwater.  Many adult females die on the surface of the water after laying their eggs.  Like mosquitoes, dragonflies, and damselflies, mayflies molt several times when in their larval stage, during which they are also known as “nymphs.”  Nymphs graze on bacteria on the river floor.  As they grow older, they form oval-shaped gills which beat in order to regulate the flow of water and oxygen through the body.  

Mayfly Larva

During the final molt as a nymph, the mayfly floats to the surface of the water and opens its wings to enter the first flying stage, where it is known as a subimago.  Floating on the surface of the water, waiting for the strength to fly, this is the most vulnerable stage of the mayfly’s life.  Once it has the strength to fly, the mayfly will find protection under a tree or in long grasses, where it will again molt within 24 to 48 hours, entering the second flying stage as an imago.  During this final molt, the mayfly’s tails and legs grow larger, giving them more stability in flight and greater reproductive success, respectively.  Mayflies, in both the nymph and adult stages, can be recognized by their three caudal filaments, or tails, at the tip of the abdomen.  As adults, their large forewings are usually kept upright, while their hind wings are reduced or nonexistent.  Once it becomes an adult, the imago will mate and then live for only hours to a day.  This is the reason that the order Ephemeroptera was given its name: ephemeros is Greek for “lasting but a day.”

The adult mayflies may only last for a day, but they let us know that the ecosystem is strong and healthy.  In their various life stages, mayflies provide food for animals as varied as snails, fish, frogs, birds, beetles, and flies.  Mayfly nymphs are extremely sensitive to pollution and poor water quality, so their presence indicates a very healthy stream.  Students in Water Ecology, collecting the macroinvertebrates they find on the stream bottom, always come up with mayfly larva, those organisms that tell us just how clean the Big Flatbrook is.  As an indicator species, this aquatic insect is very instructive of the healthy aquatic environment that students wade through on sunny afternoons.  Whether they find “wigglers,” “tumblers,” “toothed ones,” or those who “last but a day,” students curious enough to get their feet wet and flip over a few slippery river stones have a great deal to learn from the aquatic insects found in the Big Flatbrook.

References:

Introduction to the Odonata. (n.d.). Odonata: Dragonflies and Damselflies. Retrieved May 23, 2012, from http://www.ucmp.berkeley.edu/arthropoda/uniramia/odonatoida.html

Mayflies. (n.d.). Ephemeroptera. Retrieved May 23, 2012, from http://www.ucmp.berkeley.edu/arthropoda/uniramia/ephemeroptera.html

The dragonflies and damselflies of New Jersey. (n.d.). New Jersey Odonata. Retrieved May 23, 2012, from http://www.njodes.com/

The Life Cycle of the Mosquito. (n.d.). Mosquitoes. Retrieved May 22, 2012, from http://www.mosquitoes.org/LifeCycle.html

Wild Geese

And in this annual barter of food for light, and winter warmth for summer solitude, the whole continent receives as net profit a wild poem dropped from the murky skies upon the muds of March.  
 –Aldo Leopold, A Sand County Almanac

Though the winter has been mild, Lake Wapalanne has been at least partly frozen for most of the winter.  The thawing of the ice on the lake has been met with annual visitors in search of open water: Canada Geese.  Several pairs of the well-known birds have been seen around the lake, honking defensively at passersby as they stake out their nesting sites.

Canada Geese (Branta canadensis) are the most widespread goose in North America.  Everyone recognizes these long-necked, black-headed birds as they graze on lawns, pick through the stubble in last summer’s cornfields, or fly in their characteristic V formations across the gray sky.  Their deep, musical honking is a classic sound heard in the autumn as winter approaches and again when spring arrives.

The Canada Goose has a brown body and wings, black tail, tan or cream-colored breast, black head and neck, and white chinstrap.  This large waterfowl has large, webbed feet and a wide, flat, black bill.  Canada Geese live near water, grassy areas, and grain fields.  They are often found in parks, golf courses, suburban areas, and other places with large lawns both because they feed on grass and because the open space allows them an unobstructed view of potential predators.  In addition to grasses, the geese also eat sedges, skunk cabbage leaves, and eelgrass.  During the fall and winter, they will commonly eat berries, seeds, and grain and corn kernels from agricultural fields.

Canada Geese mate for life.  Pairs remain together throughout the year, and the birds are often found in large flocks.  Mates will choose each other based on size: larger males will mate with larger females and smaller males will mate with smaller females.  This practice is known as “assortative mating.”  Size may also indicate subspecies of geese; the birds generally get smaller as one moves northward.  There are at least eleven recognized subspecies, and the four smallest forms are considered a different species: the Cackling Goose.  Subspecies are also recognized by color; the geese tend to be darker as one moves westward.

In early spring, the pairs of geese break away from their flocks and begin to defend their territory, as the couples are currently doing at Lake Wapalanne.  As long as population density permits it, geese will not nest within sight of each other.  The birds are very defensive of their nesting sites, using a variety of threat displays to keep other geese away.  They will pump their heads, open their bills with their tongue raised, and hiss and honk until the intruding goose retreats.  The birds are so aggressive that they will even grab each other by the breast or throat and use their wings to hit each other.

Once territory has been staked out, the female will select the nest site and build her nest.  The nest is a large, open cup made of dry grasses, lichens, mosses, and other plant material.  It is built on the ground, often on a slightly elevated site, and lined with down and body feathers.  The female will incubate two to eight eggs alone while the male guards the nest site.  In order to properly guard the nest, the geese prefer a site with an unobstructed view.

The female will incubate her creamy white eggs for just under a month.  When they hatch, the goslings are covered with soft, yellowish down.  After only one or two days, the baby birds can leave the nest to walk, swim, and feed.  Even though they are independent enough to leave the nest so early, they stay with their parents constantly.  The young birds will remain with their parents for their entire first year, though as they grow, they become more social and congregate with other families at good food sources.

Come winter, Canada Geese may migrate long distances to spend the winter in the southernmost parts of their range.  Some geese, however, may migrate short distances or not at all.  Recently, researchers have found that the geese are not flying quite as far south as they used to.  One reason for this change in migration patterns could be that waste grain from agricultural fields has become more available as a food source during winter months.  As long as the geese find open water and food resources, they can survive icy winter temperatures.

Even though some Canada Geese are resident to an area, the species itself has come to represent migration.  Flying both night and day, the flocks of family groups and individuals are witnessed by many as they move freely between Canada and Mexico.  These migrations symbolize both change, on a yearly scale, and repetition of nature’s cycles on a longer time scale.

Quite simply, the arrival of Canada Geese at the tail-end of winter is a sure symbol of the approaching spring.  In his chapter “March: The Geese Return” of A Sand County Almanac, Aldo Leopold writes with excitement and joy about the arrival of geese on his farm: “Once touching water, our newly arrived guests set up a honking and splashing that shakes the last thought of winter out of the brittle cattails.  Our geese are home again!” (19).  Leopold’s exclamation that the geese are “home again” shows his enthusiasm for their arrival.  Not only have the birds brought spring with them, they also appear on Leopold’s farm like old friends who have returned for a visit.  The rambunctious honking of the geese, as well as the summer-like sound of their splashing on the water, chases the chill of winter out of the air.

References:

All About Birds. The Cornell Lab of Ornithology. 5 Mar. 2012. .

Leopold, Aldo. A Sand County Almanac and Sketches Here and There. New York: Oxford University Press, 1949.

Peterson, Roger Tory. Peterson Field Guide to Birds of North America. New York: Houghton Mifflin Company, 2008.

Who Cooks for You?

In September, last year’s AmeriCorps members gave Ashley, Danielle, Sam, and me a tour of the School of Conservation Campus.  It was one of the few warm days that remained, and we took our time near the canoes and rowboats near the docks on the Sequoya side of campus.  We sat on red benches in the Pavilion, a small building with removable walls, open to the late summer sunshine.  Looking up at the roof of the Pavilion, we could see the remains of nests made in spring by Phoebes and Barn Swallows.  In one corner of the Pavilion, an Eastern Screech Owl perched atop a song bird’s nest.  It was so motionless in sleep that at first, I believed that the owl was a taxidermied specimen, put there on display.  In fact, it was a living owl, but it wasn’t until the bird squinted its eyes open and peeked at me that I was convinced.

The Eastern Screech Owl (Otus asio) is one of seven owls found in New Jersey.  The most common species found in the state are the Eastern Screech Owl, Great Horned Owl (Bubo virginianus), and Barred Owl (Strix varia).  Barn Owls (Tyto alba) and Northern Saw-whet Owls (Aegolius acadicus) are also found in New Jersey, and the Long-Eared Owl (Asio otus) and Short-Eared Owl (Asio flammeus) can be found overwintering here.  

Primarily nocturnal birds with excellent camouflage, owls are often better known by sound than by sight.  In Walden; or, Life in the Woods, Henry David Thoreau writes extensively about the owls that he hears nightly at Walden Pond.  Thoreau describes the Eastern Screech Owls as “Wise midnight hags!” whose “wailing” and “doleful responses” he loves to hear.  In fact, Thoreau states, “I rejoice that there are owls…It is a sound admirably suited to swamps and twilight woods which no day illustrates, suggesting a vast and undeveloped nature which men have not recognized” (82).  Known only for the sounds they make at night, owls come to represent mystery and darkness, obscurity and ghostly twilight.  From the Eastern Screech Owl’s whistled trill and the Great Horned Owl’s deep hooting to the Barred Owl’s cackling and cawing and the Barn Owl’s hissing scream, owls are recognized by their haunting calls.

Contrary to popular belief, owls cannot turn their heads all the way around.  Owls turn their heads three quarters of the way around in order to change their field of vision.  An owl doesn’t have enough room in its head for eye muscles; therefore, the owl relies on turning its head to see from different angles.  Owls also have 14 vertebrae in their necks—twice as many as in mammals—that allow them to turn their heads.  Because owls can move their heads so far and so rapidly, it often appears that they can turn their heads around completely.  This ability to have eyes in the back of their heads helps make these birds excellent hunters, able to look in almost any direction to see the animals they hunt.

These nighttime birds of prey mainly hunt rodents such as mice.  The Eastern Screech Owl will also eat insects, songbirds, and earthworms; they will even dive for fish or crayfish.  The Barred Owl also eats crayfish; it is believed that this causes the belly feathers of some Barred Owls to turn pink!  The more vicious Great Horned Owl will eat larger animals, like rabbits, squirrels, geese, and snakes.  This owl will also prey on crows, and because of this, crows regularly mob and harass owls.  The Great Horned Owl will even eat skunks!  Most owls eat a variety of small mammals, songbirds, and large insects.  The Barn Owl and Long-Eared Owl have particularly good hearing and are able to catch prey in complete darkness.  The prey of owls can be discovered by studying owl pellets, or small masses of undigested parts from the owl’s food.  Inside an owl pellet, one can find many indigestible materials, from the bones of rodents to the exoskeletons of insects to fur or feathers.  These indigestible materials collect in the owl’s stomach, and a pellet is formed.  The pellets are expelled before the night’s hunting by regurgitation; owl pellets can often be found beneath the bird’s nest or a regular roost within the owl’s hunting grounds.

Unlike most birds, owls do not build their own nests.  Some owls, like the Great Horned Owl, Long-Eared Owl, and Barred Owl will lay their eggs in the existing nest of a hawk, heron, crow, magpie, or squirrel.  The Barred Owl may also lay her eggs in a tree cavity or an old woodpecker hole, as will the Eastern Screech Owl and the Northern Saw-whet Owl.  The Short-Eared Owl will lay her eggs in a shallow, grass-lined depression, well-hidden by vegetation, and the Barn Owl will simply lay her eggs on a bare surface, such as in the corner of a barn or attic.  Depending on the species, owls will lay between two and eleven eggs; females will incubate the eggs themselves.  In some species, the males will hunt for food and protect the nests.  Most owl chicks will be ready to leave the nest after four to ten weeks, depending on the species.

This winter, New Jersey has had an unexpected visitor.  On November 8, 2011, a juvenile female Snowy Owl (Nyctea scandiaca) was spotted at Merrill Creek Reservoir in Warren County.  At the time of this writing, the owl could still be found there.  This Snowy Owl has likely taken up residency here in New Jersey, far south of its normal range, due to a strong breeding season in the northern tundra of Canada and Alaska this past summer.  Such a rise in population has sent younger birds further south to look for food this winter.  The arrival of the Snowy Owl in New Jersey has been an exciting opportunity for birdwatchers, who have flocked to Merrill Creek to view and photograph the bright white bird.  Almost as unusual as seeing the Snowy Owl in New Jersey is getting the chance to view any of the state’s seven owl species.  The lucky birdwatcher gets the chance to view these elusive, nocturnal, mysterious birds.  Their hooting, cackling, and hissing at night are indicators of their presence, even if we don’t get the chance to see these big-eyed nighttime birds.
 

References:

All About Birds. The Cornell Lab of Ornithology. 25 Jan. 2012. .

"Barred Owl." Science Museum of Minnesota. Warner Nature Center. 25 Jan. 2012.

Malok, Andre. "Snowy Owl Takes up Residence at Merrill Creek Reservoir in Warren County." NJ.com. The Star Ledger, 6 Jan. 2012. 26 Jan. 2012.    ledger/2012/01/snowy_owl_takes_up_residence_a.html

Thoreau, Henry David. Walden; or, Life in the Woods. New York: Dover Publications, 1995.

Vanner, Michael. The Encyclopedia of North American Birds. Barnes and Noble, 2003.

“What Is an Owl Pellet?” Owl Pellets. 25 Jan. 2012.

A Long Winter's Nap

When the air grows icy and winter sets in, New Jersey’s animals have many ways of coping with colder temperatures and a lack of food.  Some, like birds, migrate.  Warblers and swallows fly south to find active insects, sparrows fly south to find uncovered seeds, and water birds fly south to find open water.  Other animals, like insects, spiders, reptiles, and amphibians will also migrate—deeper into the earth.  Salamanders and earth worms will burrow beneath leaf litter and toads will burrow under the soil, below the frost line.  Snow provides an insulating layer for these animals.

Some animals grow warm, thick winter coats, such as white-tail deer, whose winter coats are made of hollow hairs to trap extra body heat.  Birds that stick around for the winter, such as goldfinches and redpolls, grow more feathers and fluff them for insulation.  Animals like deer, birds, squirrels, rabbits, and beavers stay active during the cold months.  Even in the coldest places, staying active will keep an animal alive through the winter.  For example, the arctic fox in the Arctic and the emperor penguin in the Antarctic will survive the cold because of their appropriate insulation, considerable energy reserves, and ability to successfully compete for continuing food sources.

Several of New Jersey’s animals have another adaptation for surviving the cold winter months, however.  They will either enter a state of torpor or prolonged torpor, otherwise known as hibernation.  To enter into a state of torpor is to enter into a state of hypothermia, accompanied by inactivity and lowered metabolism, body temperature, and heart rate.  There is a fall in oxygen consumption and breathing rates and a restriction of blood flow to the main organs.  Why would an animal adapt to enter such a state?  This type of deep sleep is a form of energy conservation.  Animals that live in cold climates develop such sleeping patterns when food gathering becomes more difficult and it would take too much energy and body heat to search for food.

Torpor is driven by ambient temperature and food availability.  Many of New Jersey’s mammals, such as the black bear, chipmunk, raccoon, and skunk, enter states of torpor to make it through the cold months.  To prepare for the winter, black bears accumulate body fat throughout the summer and autumn.  In late fall, when food becomes scarce, they make their dens and enter them for the winter.  Black bears lose about 25 percent of their body weight during the winter, but they stay in good physical condition, and they will awaken and leave their dens periodically, especially if food is available.  Female black bears give birth during the winter, and their fat stores from the summer and autumn provide enough nourishment to suckle their young.  Even in the arctic and sub-arctic, bears are not true hibernators.  They will simply experience seasonal lethargy and periods of torpor to get through the winter.

Animals that maintain very high metabolic rates will often go into daily torpor.  This allows them to sleep through times when it is difficult to find food.  For example, bats will enter torpor during the day, when it is difficult to find insects.  Their bodies therefore use less energy, and food will last longer in their bodies.  They will wake up again when it is time to search for more food.  Bats take about two hours to reduce their metabolic rates, drop their body temperatures, and enter into a state of torpor.  When they are ready to awaken, it will take about an hour.  They warm up by shivering violently and contracting their muscles.  Frogs will enter torpor during the night because nighttime air temperatures are too cool for them.  They therefore use less food and energy to keep warm during the night.  Other animals that enter daily torpor include hummingbirds, swifts, nightjars, nighthawks, poor-wills, and goatsuckers.  Doves and pigeons enter a shallow state of torpor when they are deprived of food.

Hibernation is a sustained state of torpor.  Entry into and exit from hibernation are governed both by internal signals such as hormone changes and external cues such as day length and temperature.  Whether in a state of torpor or a state of hibernation, animals have the ability to wake spontaneously, despite the temperature.  Animals hibernate for several months, though they will occasionally awaken throughout the winter.  They will remain in a state of deep torpor for several weeks at a time, and then awaken for several hours before entering into a deep state of torpor again.  These short periods of arousal and activity may serve to maintain organs, tissues, and cells; animals are susceptible to parasitic infections while hibernating, so waking up occasionally may boost their immune systems.

Very few of New Jersey’s mammals are true hibernators.  Only the jumping mouse, woodchuck (or groundhog), and little brown bat hibernate through the winter.  For these animals, foraging for food and maintaining their normal core body temperatures during the winter months are energetically too costly.  Like animals who enter short periods of torpor during the winter, animals that enter hibernation will also prepare in the summer and autumn by eating more food than usual and building fat stores.  An animal in hibernation will not lose any of its muscle; it will just lose its stored body fat.  The longer the animal is in a deep state of torpor, the thicker its layer of fat will be.  When hibernating animals awaken, they will be much thinner, but they will have maintained their muscle.  As in torpor, hibernating animals slow their heartbeat, breathing, and metabolism.  Animals that hibernate drop their body temperatures lower than those who enter torpor.  Their body temperatures will drop so low that they will match that of the ambient air temperature!  But hibernating animals protect themselves in sealed dens that remain above freezing temperature because of insulation and geothermal heating.  During the depth of winter, the length of time that animals stay in their deep state of torpor lengthens.  As spring comes closer, the periods of torpor decrease and the periods of activity increase until one day, arousal marks the end of hibernation.  Temperature and the instinct to mate are other factors that call animals out of hibernation.  

The groundhog doubles in weight from May to September to prepare for a four to five month period of hibernation.  On Groundhog Day, when we call the groundhog out of its den and look for its shadow, we are awakening an animal deep in sleep.  Depending on factors such as temperature and photoperiod, the groundhog may reenter a state of prolonged torpor to make it through the remaining winter months.  As humans, though, we don’t have that option; we will have to continue emerging from the warm dens of our beds, bundling up, and staying active throughout the cold season.

              

References:

"Animals at the Extremes: Hibernation and Torpor." Open Learn: The Open University. Web. 27 Dec. 2011. http://openlearn.open.ac.uk/mod/oucontent/view.php?id=398616&direct=1.

Harris, Steve. "How to Tell Torpor from Hibernation." Discover Wildlife | Wildlife and Photography at Its Best with BBC Wildlife Magazine. 15 July 2010. Web. 27 Dec. 2011. http://www.discoverwildlife.com/british-wildlife/how-tell-torpor-hibernation.

"Hibernation." ThinkQuest. Web. 27 Dec. 2011. http://library.thinkquest.org/TQ0312800/hibernate.htm.

"Mammalian Hibernation." University of Calgary, 26 Feb. 1999. Web. 27 Dec. 2011.  http://people.ucalgary.ca/~kmuldrew/cryo_course/cryo_chap12_1.html.

"Torpor." ThinkQuest. Web. 27 Dec. 2011. http://library.thinkquest.org/TQ0312800/torpor.htm.