Naturalist Fact : Virginia Opossum (Didelphis virginiana)  

virginia-opossum

 

A common mammal species throughout the Eastern and Midwestern US, the Virginia Opossum is the only marsupial to live North of Mexico.  They range from southern Canada to northern Costa Rica with some populations found in California presumably brought there by travelers as a food source during the depression.  Although they are also commonly referred to as just possums in Georgia, the term possum is technically used to refer to a specific suborder of arboreal marsupials found only in Australia, and Opossum refers to new world marsupials found in North and South America. The term opossum was actually borrowed from the Algonquian name for them, aposoum, meaning “white dog”. The average Virginia Opossum is about 2 feet in length weighing around 8 pounds; female opossums are smaller than males, with male opossums ranging 12 to 15 pounds. They have a very short lifespan, typically only surviving a year in the wild. Like most marsupials the female Virginia Opossum has a pouch which is lined with fur where the young develop. A female Opossum can give birth to as many as 20 young, which at birth are not much larger than a honeybee, about a half an inch in length. Upon their birth they must crawl to the pouch of the female and attach themselves to one of the 13 teats within the mother’s pouch. After about 60 days the young will leave the pouch and travel on their mothers back until about 100 days of age where they are then independent and can forage on their own. Virginia Opossums are generally nocturnal, being most active at night, and spend much of their time in the trees, utilizing their furless prehensile tail as a fifth limb to help them navigate their arboreal habitat. They are an opportunistic omnivore, eating anything they can find including fruits, nuts, and carrion, as well as predating on small mammals and reptiles.

Recent studies have found that Opossums play an important role in regulating disease transmission in the habitats where they exist. Researchers experimentally found that half of all ticks introduced to mice were able to attach and feed, while only 3.5% of ticks introduced to opossums would attach. The study found that those ticks that failed to attach where eaten by the opossums during grooming. In field surveys they found that the average opossum carries about 200 ticks, and if that is 3.5% of the ticks that try to feed on an opossum, then the average opossum eats up to or more than 5,500 ticks. These same researchers hypothesize that the removal of opossums can have a profound effect on tick populations and increase transmission of ailments such as Lyme disease to other creatures, including people.

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Naturalist Fact: The Moon

Image Credit: GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter NASA

Image Credit: GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter NASA

With little light pollution on Little St. Simons Island, it is a great place to explore the night sky. Although it travels through several phases each month, Earth’s moon is usually the most conspicuous sight in the night sky. The moon’s illumination is the result of the sun’s light reflecting off the moon’s surface, and as the moon rotates around the Earth, we are able to see differing proportions of the moon.

The moon is estimated to be about 4.5 billion years old, about the same age as the earth. The most accepted theory for the formation of the moon, is that while the earth was still very young, a rock comparable to the size of Mars collided with Earth. The impact of this collision sent large pieces of rock into Earth’s orbit, which aggregated into one body to form our moon.

It takes the moon about one month (28 days) to orbit the earth, and it takes about the same amount of time (27.53 days) for the moon to complete a rotation around its own axis. Consequently, the same side of the moon is always facing Earth. Depending on the phase of the moon, we can see a certain portion of that side each night.  At its fullest, we can see a little more than half of the moon (59%). The other 41% is the side that never faces Earth, also known as “the far side.”

The moon’s surface exhibits an interesting array of geographical features. The large dark areas are called seas or maria, and were once huge lava plains. Craters appear much lighter than the maria, and appear like starbursts with lines radiating out from the center. All the craters were formed by meteor collisions. The moon also has mountain ranges, valleys, cliffs, and other changes in topography. The best time to observe these features through binoculars or a scope, is several days before and after the full moon when the angle of the sunlight gives the most definition to its features.

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Naturalist Fact: Scarlet Snake

Scarlet-Snake-3

The Scarlet snake (Cemophora coccinea) is an elusive snake, rarely found by humans.  This species is quite slender and reaches a maximum length of about thirty inches.  These snakes always have wide red bands separated by yellow or white bands which are bordered with black.   The bands do not encircle the entire body, leaving the belly of these snakes white or cream-colored.  Often mistaken for a venomous look-alike, the coral snake, there are some morphological differences that can help to distinguish between the two.  Firstly, the red bands do not touch the white or yellow bands, as they do in the coral snake.  Scarlet snakes also have a pointed snout that is red, while coral snakes have a black-tipped snout.

Scarlet Snakes are the only snake species on Little St. Simons Island that is considered nocturnal, which is usually the only time they are observed moving on the surface of the soil or substrate.  These snakes are semi-fossorial, spending most of their time underground.  Occasionally Scarlet Snakes are found in or under logs, boards, tin, rocks, or leaf litter.  The pointed snout and slender body allows them to burrow through dry, loamy, and sandy soils.  These snakes are most commonly found in habitats where this sandy and well-drained soil is predominant, such as pine flatlands, dry prairies, maritime hardwood forests, and sweetgrass prairies.  Scarlet Snakes are found from Southern New Jersey, south to Southern Florida, and West to East Texas.

Reptile eggs make up the majority of the Scarlet Snakes’ diet, but they may also prey on lizards, small snakes, or frogs.  If an egg is too large for a Scarlet Snake to swallow whole, they may break it open with specialized enlarged teeth before swallowing it.  Very little is known about Scarlet Snake reproduction due to the secretive nature and burrowing habits.  In early summer (typically June), female snakes will generally lay 3-9 elongated and leathery eggs underground (1-13/8” long).  The young are about 6 inches long when they hatch in late summer, and closely resemble adult snakes in coloration.

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Naturalist Fact: Hummingbird Clearwing Moth

Photo Credit: Birds & Blooms

Photo Credit: Birds & Blooms

The Hummingbird Clearwing Moth (Hemaris thysbe) is frequently mistaken for a hummingbird or bee based on the moth’s appearance and behavior. Adult coloration is variable, but a “furry” olive green and burgundy back is common. Its underside is light yellow or white on the thorax, and burgundy on abdomen. The wingspan is 1.6 to 2.2 inches, and the wings always have a dark reddish border with a transparent center. These moths have fast wingbeats, and hovers while collecting nectar with a long feeding tube from flowers.

During its four weeks as a caterpillar, it feeds mostly on honeysuckle, cherry trees, and hawthorns. As a moth, it feeds on a variety of flowers. These moths feed during the day, which is another factor to their mistaken identity. In the southeast, there are two broods with most activity during the summer months.  The largest population of Hummingbird Clearwing Moths is along the east coast ranging from Florida to Maine. A west coast population ranges from Alaska to Oregon.

 

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Naturalist Fact: Alligator Gar

 

http://www.thealexandriazoo.com/mAllAnimals.html

http://www.thealexandriazoo.com/mAllAnimals.html

 

Alligator gar (Atractosteus spatula) are a true prehistoric creature that have remained a hearty predator for millions of years. They have been compared with the earliest terrestrial tetrapods which evolved from the ocean during the late Devonian period. Alligator gar are the largest species in the Gar family (Lepisosteidae), reaching up to 400 pounds and 12 feet in length! The rostrum, or mouth of an alligator gar is short and broad with two rows of extremely sharp alligator-like teeth on the upper jaw, unlike other species of gar which contain one row of teeth. These fish have an elongated body with a single dorsal and anal fin posterior near the heterocercal (rounded) caudal fin. A thick row of nonoverlapping and diamond shaped ganoid scales cover the body, acting as an armor layer to protect from predation. Alligator gar are generally dark olive-brown in color, with dark brown fins and a yellow belly. It is easy to spot gar in a body of water because they contain a lung-like gas bladder which they inflate by taking in gulps of atmospheric oxygen from the water surface! This allows them to reach various levels of the water column by inflating and burping out gas from their gas bladder.

It is common to find alligator gar in slow-moving pools and creeks extended from larger rivers, bayous, lakes, and swamps—mainly in the Mississippi Delta. Alligator gar are mainly piscivores, or consumers of fish, but also eat snakes, small mammals, turtles, and birds. Females generally lay 138,000 eggs which cling to vegetation or rocky substrate in which two or three males will fertilize simultaneously. Females can also live up to 50 years, while males only live up to 25 years old!

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Naturalist Fact: Northern Gannet

Naturalist Fact

Northern Gannet (Morus bassanus)

northern gannet

The Northern Gannet is a large seabird, and the largest member of the gannet family.  These birds have long, slender, black-tipped wings with wingspans reaching about 70 inches from tip to tip.  Adult birds have yellowish heads and all white bodies (pictured above) while immature gannets are very dark with white spots.  It can take three or more years to attain full adult plumage.

Gannets are well known for their spectacular feeding behavior, which includes aerial plunges from heights up to 130 feet above the water.  Just before entering the water, the wings are pulled behind the back to help to bird penetrate deeper into the water. Once underwater, the gannets will then use their feet and wings to propel themselves further in pursuit of prey.   Most dives are relatively shallow but dives to depths of 72 feet have been observed.  Small, schooling fishes are the most common prey, but gannets will also opportunistically take squid as well.

These impressive predators are colonial breeders, nesting only on the rocky cliffs of offshore islands during the summer.  There are just six colonies of breeding gannets in North America; three colonies exist in the Gulf of St. Lawrence (Quebec), and three off the coast of Newfoundland.  Large nests are constructed of compacted mud, seaweed, grass, and feathers, with excrement being used as cement.  One pale bluish-green egg is laid each nesting season, and chicks are nearly bare when newly hatched.

Winters are spent entirely at sea, and these birds can be seen diving off the beach at Little St. Simons Island in search of prey.  A spotting scope or binoculars may be necessary to observe them as they typically stay far offshore, but on occasion they can be seen within 100 yards of the beach.

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Naturalist Fact: Wood Stork

wood stork 1

William Newton/ Cornell Lab of Ornithology

The Wood Stork is a large, white wading bird with black flight feathers. This bird has a long, decurved bill on its bald head. Its wingspan averages 5.5 feet, making it unmistakable in flight.

Wood Storks are the only species of stork breeding in North America. In the United States, they breed from Florida to southern North Carolina. Other breeding sites are in South America, Central America, and the Caribbean. They are social animals, so they nest in colonies and can have up to 25 nests in one tree. Cypress and mangrove are their preferred nesting trees. On average, a pair of nesting Wood Storks and their young consumes 443 pounds of fish during the breeding season.

Due to a decline in population, Wood Storks have been on the Endangered Species List since 1984. The loss of wetland habitat by development, agricultural practices, and water management practices are reasons for their endangerment. Wood Storks are an indicator species for a healthy, wetland ecosystem.

Wood Storks feed mainly on freshwater fish, and use tactilocation to obtain their meals. Tactilocation is feeding by groping with a bill, and not using eyesight. Wood Storks submerge their bill under water, walk slowly, and sweep their bill side to side. When their bill snaps shut on a fish, their 25-millisecond reflex action is the fastest among vertebrates.

William Newton/ Cornell Lab of Ornithology

William Newton/ Cornell Lab of Ornithology

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Naturalist Fact: American Mink

American Mink  (Neovison vison)

American Mink

The American mink is a fascinating voracious predator in the Mustelidae family, which includes otters, weasels, badgers, wolverines, and minks.  The Mustelidae family is actually the most diverse family within the order Carnivora.

American mink are an extremely widespread mammal found across North America, ranging from Alaska and Canada through the lower 48 states, with the exception of extremely dry areas of the Southwest.  The American mink has also been introduced to large portions of Europe where it is classified as an invasive species, linked with the decline of several native species including the European mink.   Although often difficult to view due to a secretive nature, the mink is quite common throughout much of its range.  In suitable habitat, populations may reach densities of 9-22 individuals per square mile.  Mink are considered semi-aquatic, and are rarely seen far from a water source such as streams, lakes, swamps, and marshes.  Occasionally mink can persist in dry environments if there is a steady food supply.  The majority of mink populations occur around fresh water, but coastal salt marsh also produces fine habitat for mink, with abundant prey.

Mink are strictly carnivorous, like all members of the Mustelidae family, and have a varied diet.  Typically the diet depends on the type of prey available, and small mammals such as muskrats and rats may be eaten more during the winter months.  Other prey choices can include ducks, seagulls, crustaceans, amphibians, and other waterfowl.  Being excellent swimmers, mink can swim up to 30 meters underwater and dive up to a depth of 5 meters in search of prey.  Mink are mostly active during the night.  An elusive nature combined with cryptic coloration help mink avoid predation, but occasionally they will fall prey to coyotes, bobcat, birds of prey, and snakes.

Male individuals are very territorial with each other, and have home ranges that may overlap with several female home ranges.  Breeding occurs during the winter months, and both females and males may mate with multiple individuals.  Gestation typically last from 45 to 75 days, and average litter size ranges from 1 to 8 kits are usually born in April or May.  Most kits become independent and find new territory from 6 to 10 months of age, and both male and females become sexually mature around 10 months of age.

The dense and fine pelage (fur) of mink makes it among the most important furs on the fur market.  Historically all pelts came from trapping wild populations which led to declines in populations, but most pelts in the fur trade are now produced on farms.  Wild populations have since recovered from the extensive wild trapping and are considered of least concern by the IUCN (International Union for Conservation of Nature).

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Naturalist Fact: American Holly

American Holly (Ilex opaca) is an evergreen shrub and tree that grows 10-20 meters tall from Massachusetts to Florida, west to Texas. Holly leaves are a glossy green and range 5-7.5 cm long and 2-4 cm wide. Leaves form in an alternate pattern, and have several sharp points along the edge. Holly “berries” are called drupes, and ripen from a green to a bright red color in the fall. Drupes are poisonous to humans, and will stay on the plant throughout the winter. Small white flowers bloom from April to June. Holly is commonly found in the understory of a forest due to its shade-tolerance.

Many animals use American Holly as a food source including Wild Turkeys, Northern Bobwhite, songbirds, deer, raccoons, Eastern Box Turtle, mice, chipmunks, squirrels, and cottontails. Holly trees also provide nesting habitat and shelter for several animals as well. These animals aid holly by spreading its seeds to create more plants.

Around Christmas and the holidays, holly is a very popular decoration, and can be overharvested in more populated areas. This plant is a common landscape species, and often used for hedges. Its wood is used for piano keys, violin pegs, cabinets and handles. Nectar is collected from holly to make honey as well.

Benny J. Simpson, Texas A & M Dallas

Benny J. Simpson, Texas A & M Dallas

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Naturalist Fact: Grass Shrimp

Grass Shrimp (Palaemonetes sp.)

grass shrimp

http://goo.gl/Oz2KBS

Grass shrimp have multiple common names, including grass shrimp, popcorn shrimp, glass shrimp, glass pawns, jumpers, and hardbacks.  Compared to commercial species of shrimp, grass shrimp are quite small, rarely exceeding two inches in length.  These tiny decapods are often nearly transparent (hence the one common name of glass shrimp), and have a well developed rostrum or horn on the dorsal and forward portion of the head, much like many commercial shrimp species.  This ‘horn’ can be quite sharp and may aid in defense against predators.  Little teeth-like projections found on and around this rostrum are used to help determine the particular species of grass shrimp under a dissecting scope (different placements), although many errors in species identification are made due to the morphological similarities.

These shrimp exist in many estuarine environments, and are often associated with some sort of underwater structure such as submerged plants and very commonly, oyster reef habitats.  Structure such as submerged grasses or oyster beds provide ample protection from predators like fish, and also provide the shrimp with a food source.  These shrimp typically stay along the edges of creeks in very shallow water, but have been found up to fifty feet deep.  Grass shrimp are typically considered detritivores, feeding mainly upon dead or decaying plant matter; however their diets can consist of a wide variety of organisms.  In captivity grass shrimp have been known be cannibalistic, and will also predate on tiny polychaetes, oligochaetes and nematodes (marine worms) in the wild.  Because these tiny crustaceans often fall prey to fishes and other carnivores, they are extremely important as a link between trophic levels.  Energy and nutrients are transported between primary producers and higher trophic levels with grass shrimp being an important vector.  More research is needed to assess the populations of grass shrimp and how humans may be affecting these ecologically important organisms.

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