Friday, December 5, 2014

Merry Mistletoe




From the earliest times mistletoe has been considered one of the most magical, mysterious, and sacred plants found in European folklore.  Originally used to bestow life and fertility, as a protection from poison, and as an aphrodisiac, in medieval times branches of mistletoe were hung from the ceiling to ward off evil spirits. With the process of immigration and settlement of North America, traditions associated with the European plant were transferred to the New World and evolved into a folklore all its own.


In Central Texas, two species of mistletoe are native, the Christmas Mistletoe (Phoradendron tomentosum) and Oak Mistletoe (Phoradendron leucarpum).  The genus comes from the Greek ‘phor’ which means thief and ‘dendron’ which means tree, as both species are semiparasites that steal water and nutrients from their host trees.  Christmas mistletoe has small, elliptical evergreen leaves and smooth green stems covered by short hairs, with tiny green flowers on the male plant and shiny white berries on the female plant. It is widely used in the United States as a Christmas decoration, and is especially common growing on Sugar Hackberry, Cedar Elm, and Honey Mesquite trees in Texas, Louisiana, and Oklahoma.


Native north to New York State, south to Florida, and west to New Mexico, Oak Mistletoe is another common mistletoe hung at Christmastime.  It is a larval host plant for the Great Purple Hairstreak butterfly, and while similar in appearance to Christmas Mistletoe, its berries are covered with a sticky substance poisonous to humans but relished by winter resident birds such as Cedar Waxwings, Eastern Bluebirds, and American Robins.  These birds eat the berries and spread the seeds through their droppings and by wiping their beaks on tree branches, both of which may cause a new plant to take hold and become established.

Great Purple Hairstreak

While ancient folklore has attributed a wide range of mystical abilities to mistletoe, none is more fascinating than the myth of Frigga, the Norse Mother Goddess worshiped by pre-Christian people of northern Europe, and how mistletoe became her sacred plant.  She was believed to be the mother of Balder, the God of the Summer Sun, who had a dream of death.  Alarmed by this dream, Frigga went to all the elements, plants, and animals to seek a promise that no harm would come to her son.  Balder was thought to be safe from harm by anything on or under the Earth.  

But Balder’s enemy, Loki, was the God of Evil, and he knew of the one plant that Frigga overlooked.  It was the lowly mistletoe, which grew neither on nor under the Earth itself, but on the branches of oaks and other trees.  Loki made an arrow tip with the mistletoe, and gave it to the Hoder, the blind God of Winter, who used it to strike Balder dead.  The sky paled and everything wept for the Sun God, who was restored by Frigga after working with the elements for three days. The tears she shed for her son were said to be the pearly white berries of the mistletoe, and in her joy at his resurrection she kissed everyone who passed beneath the tree on which it grew.  

Thus began the custom that whomever should stand beneath the humble mistletoe will come to no harm, but receive only a kiss as a token of love.  Merry mistletoe to you and yours!



Thursday, November 27, 2014

Shadow Tails

Fox Squirrel, Sciurus niger


The word ‘squirrel’ comes from the Greek ‘sciourus’, meaning ‘shadow tail’, and refers to the bushy appendage possessed by most all squirrel species.  They are members of the rodent family, and Texas is home to 10 species of squirrels with 4 of them common in the Austin area.

Along with their bushy tails, squirrels are generally slender animals with large eyes and soft fur. Their front limbs are shorter than their hind limbs, with 4 or 5 toes on each foot.  Their front feet include a usually underdeveloped thumb, and all toes have sharp claws for climbing trees and quickly clamoring over uneven terrain. Squirrels are strongly vegetarian, and feed mostly on a wide variety of seeds, nuts, fruits, buds, bark, and leaves.  Their vision is sharp and they have ‘vibrissae’ or specialized hairs on their head and limbs, which afford them an excellent sense of touch.   

The most common tree squirrels in Central Texas are the Eastern Fox Squirrel (Sciurus niger) and the Eastern Gray Squirrel (Sciurus carolinensis). A large squirrel with rusty or reddish underparts and grayish or brownish upperparts, the Fox Squirrel prefers open woodlands of mixed trees and riparian areas along rivers and streams, and makes its dens in hollow trees or nests made of leaves.  Their diet is largely made up of acorns which are buried in winter and relocated through their keen sense of smell. Mating occurs in January/February, and again in May/June, with offspring born in March and July.  

The Gray Squirrel is a medium-sized squirrel with grayish upperparts with white-tipped hairs, white underparts, and a white spot at the base of its ears in winter.  Gray Squirrels live in dense live oak stands and bottomland areas, with the Austin area in the westernmost part of their range.  There are usually two openings to their nests, which are otherwise similar to the Fox Squirrel, as is their diet and breeding cycle.  Destruction of bottomland habitat from logging, overgrazing by livestock, and development are the main reasons why gray squirrels are only locally common, and declining in many areas.      

Rock Squirrel, Spermophilus variegatus

Our most frequently seen ground squirrels include the Rock Squirrel (Spermophilus variegatus) and the Mexican Ground Squirrel (Spermophilus mexicanus).  A rather large, stout squirrel with a blackish head and upper back and a mottled grayish-brown rump and tail, the Rock Squirrel is nearly always found in rocky canyons, cliffs, and rock piles, where they make their dens.  While they can climb trees, they prefer to be ground dwellers, where they forage for acorns, nuts, insects, and berries.  In Central Texas, these squirrels hibernate beginning in November, and emerge in late February or March to begin breeding.

Mexican Ground Squirrel, Spermophilus mexicanus

The western edge of Austin is the easternmost range for the Mexican Ground Squirrel, a rather small squirrel with about nine rows of squarish white spots on its back and a moderately bushy tail. They prefer brushy or grassy areas, including mowed lawns and overgrazed pastures and live in burrows dug into the soil.  They eat chiefly green vegetation and insects, but are one of the few squirrel species that will eat meat.  Breeding begins in late March or early April, with a brood chamber built into a side tunnel in the deepest part of their burrow. 

Anyone who has seen a squirrel running along a tree limb or across an open road with its bushy tail undulating and waving behind it, or spotted a squirrel sitting with its tail curled over its back while it eats or surveys its surroundings, can appreciate why their name means shadow tail!

Thursday, October 30, 2014

Blooming Mist



All members of the Aster family, the Eupatorium genus of flowering plants are characterized by their medium-tall to tall stems and triangular, toothed leaves, topped with a cluster of small composite flowers.   They grab our attention in the fall as their blooms are prolific, like small clouds of mist, on which late-season butterflies, bees, and moths are eager to gather.  It’s easy to see why they are commonly called mistflowers, but they are also called bonesets, thoroughworts, and snakeroots.

To add to the mystery, the classification of this tribe of plants is the subject of ongoing research, and many species that were once grouped under Eupatorium have recently been moved to other plant families, or genera.  Conoclinium, the mistflowers, is a genus that includes only 4 species native to North America, and having blue to purple flowers.  Ageratina, or snakeroots, has over 250 species, and they grow mainly in warmer regions.

Commonly named for medicinal uses, various members of this plant family have been used to treat fevers and other health ailments.  Boneset alludes to the use of the plant to stimulate calcium production to speed the healing of broken bones, although the name may have also come from its use to treat dengue fever, also called breakbone fever due to the pain it inflicted.  Thoroughwort is named for its ‘perfoliate’ leaves, or the way the stem appears to pierce (or go through) the leaf.

Blue mist flower, Conoclinium coelestinum

In the hill country, Blue mistflower (Conoclinium coelestinum) is also called wild ageratum or blue boneset. Forming fairly large, bushy clumps 1-4 ft tall on moist soils near streams and in low meadows, its opposite leaves are triangular, wrinkled, somewhat thick, and smell a bit like tomato plants when crushed.  Preferring sun to partial shade, its lavender to sky-blue clusters of flowers bloom from October to December, subject to the first frost.

Gregg’s mistflower, Conoclinium greggii

Named after the 19th century explorer and naturalist Josiah Gregg, Gregg’s mistflower (Conoclinium greggii) is native to west Texas but spreading eastward to the Edwards Plateau.  Also called palmleaf thoroughwort or purple palmleaf mistflower, this 1.5 to 2 ft tall perennial has puffy, purple-blue flower heads from March through November.  Often attracting impressive numbers of nectaring Queen butterflies in the fall, this plant is found along seasonally flooded streambeds and has a lighter green, more delicate foliage.

Shrubby boneset, Ageratina havanensis

Also called Havana snakeroot, white mistflower, and white shrub mistflower, Shrubby boneset (Ageratina havanensis) is a rounded, open woody shrub, 2-5 ft tall, and multi-branched.  Its leaves are triangular with toothed edges, relatively thin, and about 2 inches long.  Blooming in October and November, the profuse flowers are fuzzy, pinkish-white, and very fragrant. Deciduous and drought-tolerant, Shrubby boneset is found on rocky hillsides and bluffs in the southern half of hill country.  Butterflies, moths, and hummingbirds, love the upright, fuzzy flower heads, and this plant is the larval host plant for the difficult to identify Rawson’s metalmark. 

Late boneset, Eupatorium serotinum

Late boneset (Eupatorium serotinum), also called late-flowering thoroughwort or white boneset, is an open, woody shrub up to 3 ft tall, with leaves up to 5 inches long, opposite and coarsely toothed.  Blooming in October and November, it likes partial shade, and is found in the eastern to central portion of the state, usually in meadows, woodland edges, near ponds or moist stream banks.   

Regardless of their classification, these native fall bloomers are a haven for wildlife.  Seek them out when hiking along your favorite trail – their intricate, fuzzy blooms beckon you to explore them up close!

Monday, October 13, 2014

Prophets and Phantoms


Mantid species

While most think of fall as a time when nature is waning and lifecycles are nearing their end, some things are just beginning.  This is the time of year when some of our most mysterious-looking insects, the praying mantids and the walking sticks, lay their eggs in anticipation of the next generation to hatch in the spring.   

The scientific order for praying mantis (Mantodea) comes from the Greek meaning 'prophet'  so named for its typical prayer-like stance.  This term is often misspelled as ‘preying mantis’ since mantids are a predatory species.  Several species exist in Texas, all of the genus Stagmomantis. Adult mantids are green to grayish brown, may reach 2 to 3 inches in length, and have well developed wings.  They have two grasping, spiked forelegs in which prey are caught and held securely while eaten. Their hunting relies greatly on their vision, and they can rotate their head nearly 300 degrees.  Consuming mostly insects, mantids are ambush predators that wait perfectly still until prey ambles near, and then strike with surprising quickness and agility. 

Praying mantids are experts at concealment, using their protective coloration to blend in with or mimic foliage, better snare their victims, and avoid predation themselves.  They do show a rocking behavior in which the insect makes a rhythmic, repetitive, side-to-side movement.  It is thought that this behavior may help them resemble vegetation blowing in the wind, but also allows them to discriminate objects from their background by their relative movement.  As generally sedentary insects, this behavior most likely replaces flying or running as a way to determine relative objects in their visual field.  When threatened they will stand tall, spread their forelegs, and fan their wings out wide to appear larger, and if further provoked will strike with their forelegs and attempt to pinch or bite.             

In the fall after mating, female mantids lay between 10 and 400 eggs, depending on the species. The eggs are typically laid in a frothy mass on the underside of a leaf or on a twig, which hardens to a tan or gray foam-like material called an ‘ootheca.’  If this egg case survives the winter, the nymphs emerge in the spring with voracious appetites, often devouring each other in their race to become mature adults.

Ootheca

Members of the Phasmatodea order of insects are commonly known as walking sticks, stick-bugs, ghost insects, leaf insects, and stick insects.  This scientific name comes from the Greek ‘phasma’ which means 'apparition' or 'phantom', and refers to many species closely resembling sticks and sometimes leaves.  At 16 species, Texas walking stick diversity is second only to California.  In fact, one species in Texas is the Giant Walkingstick (Megaphasma dentricus), which is the longest insect in the United States and grows to almost 7 inches!

Walking stick species
Our most frequently seen phasmid is the Common or Northern Walking Stick (Diapheromera femorata).  Adult males can be 3 inches long and are mostly brown, while females are larger at 4 inches and more of a greenish-brown.  Their long, thread-like antennae are about to-thirds the size of their body.  As part of their natural camouflage, their bodies are often further modified to include ridges resembling leaf veins and bark or bud-like tubercles, making them very difficult to spot. They are wingless, molt several times and may eat their shed skin as they grow to adult size.  

Phasmids feed mostly on the leaves of trees and shrubs, and often exhibit the same rhythmic movement as mantids, presumably to blend in to their surroundings and as  protection from predators.  At this time of year, the females lay anywhere from 100 to 1200 eggs individually, sticking them to vegetation or simply depositing them on the ground.   These eggs resemble tiny plant seeds and remain dormant until spring.  

While no doubt strange-looking and mysterious, mantids and phasmids are harmless to humans and beneficial components to keeping balance in our natural landscape.

Sunday, September 28, 2014

Hummingbird Highway

Ruby-throated Hummingbirds, Archilochus colubris

Some of the most abundant jewels in Texas, black-chinned and ruby-throated hummingbirds may be small, but their fall migration is a feat of gigantic proportions! 

Measuring a mere three and one-half inches long with a three and three-quarter-inch wing span, the black-chinned hummingbird weighs only three to three and one-half grams, which is about equivalent to the weight of a dime plus a dollar bill. The male is dull metallic green above, gray below, black on the chin and upper throat, with an iridescent violet lower throat known as a gorget (pronounced gore-jet). The female lacks the characteristic coloring on the chin, upper throat, and lower throat.  Ruby-throated hummingbirds are also only about three and one-half inches long with the adult male having a black upper chin and ruby-red gorget, and they are a more eastern species with Austin being the westernmost border of their range. 

Like all hummingbirds, nectar serves as its main food source, fueling the tiny bird’s extreme metabolism.  These hummingbirds feed on several species of plants, most notably native penstemons, agaves, salvias, sages, and honeysuckles.  While artificial feeders supplement their diet, they also prey on insects and spiders, particularly during nesting season, which gives them the dietary fat and protein necessary to breed.

Black-chinned Hummingbird, Archilochus alexandri

The hummingbird’s unique skeletal structure allows them to fly forwards, backwards, sideways, and even on their backs!  This requires a wingbeat frequency of about 50 beats per second, and massive muscles that make up a third of their tiny body weight.  While the males perform an elaborate flight display during courtship, no pair bond is formed between the males and females.  Females build the tiny nest (out of spider webs, mosses, and various plant fibers), incubate the eggs, and raise the young, while the males are feeding and off chasing other females.  This is unusual among birds as a whole, since this class of animals exhibits the greatest amount of monogamy among vertebrates (animals with a backbone or spinal column). 

Ruby-throated Hummingbird (Female), Archilochus colubris
While most biologists believe that the shortening length of daylight hours triggers fall migration, black-chinned and ruby-throated hummingbirds begins their long journey south from Texas in September, to spend the winter mainly in western and southern Mexico.  The number of birds migrating south may be twice that of the northward trip in the spring, since it includes all immature birds that hatched during the summer, as well as surviving adults.
  
Amazingly, for a newly hatched hummingbird, there is no memory of past migrations, only an urge to put on a lot of weight, fly in a particular direction for a certain amount of time and hundreds of miles, and look for a good place to over-winter.  Once it learns such a route, a bird may retrace it every year as long as it lives!  There is evidence that fall and spring migration routes differ, with the hummingbirds following the Texas coast back into Mexico in the fall and crossing non-stop over the Gulf of Mexico on their way north in the spring.  Perhaps the hurricane season is a factor, and these birds have developed an innate sense to avoid the Gulf during its most precarious weather season. 

The timing of the fall hummingbird migration occurs when their natural food is most abundant.  However, you can enjoy this amazing spectacle up-close by keeping your feeders full of clear, fresh sugar water through at least the end of October, and enjoying the company of these enchanting little gems as they make a rest stop in your yard!





Monday, August 4, 2014

Red and Yellow Fellow


Many of us have heard the sayings “Red on black, friend of Jack, red on yellow, kill a fellow” or “Red against black, venom lack” as a way for us to distinguish between non-venomous lookalike snakes, and the venomous coral snake.  Over 65 species of coral snakes are recognized in the New World, but in Texas we have our own version.  The Texas Coral Snake (Micrurus tener), actually ranges from the south central US (Texas, Louisiana, Arkansas) south to northeastern and central Mexico.

Texas coral snakes have the traditional black, yellow, and coral red banding coloration encircling the body that is associated with all coral snakes. They are slender snakes with smooth scales, eyes with round pupils, and average two feet in length.  Males are typically smaller than females, but both are shy and secretive, typically nocturnal and spending most of their time hiding under logs, in leaf litter, or in ground burrows.  Fairly common in the Austin area, they typically feed on other smaller snakes and occasionally lizards, and are often attracted to suburban yards and gardens where they can more easily find their prey.


While no deaths have occurred in Texas from a coral snake bite, their venom is a powerful neurotoxin that causes neuromuscular dysfunction.  Usually encountered by people when weeding or gardening, coral snakes do have a hard time injecting venom into a human because of their small, blunt head and short, fixed fangs.  Bites usually occur on the hand or in between fingers, and the snake has to chew in order to inject the venom.  Most people don’t allow them to hang on long enough to do much serious damage, but anyone bitten by a coral snake should seek medical attention immediately.


Much debate has ensured about whether or not the Texas Coral Snake’s bold coloration in and of itself acts as a warning signal to potential predators, but recent studies have shown that this coloration is only effective when combined with the coral snake’s distinctive threat behavior.  When confronted, they will raise their yellow- and black-banded tail tip and slowly wag it at the threat (presumably mimicking a strike with their similarly colored head), all while keeping their head safely and neatly tucked under a body coil.  

If you are lucky enough to run across this native red & yellow fellow, remember that Texas Coral Snakes are an integral part of our ecosystem, and enjoy their striking colors and distinctive pattern from a distance!











Tuesday, July 8, 2014

Two Heads Are Better Than One


Juniper Hairstreak, Callophrys gryneus 

Hairstreaks are mainly small butterflies, most with threadlike tails on their hindwings.  They typically fly rapidly, fitting from side to side or in circles, before sticking a landing.  Most perch with their wings closed, and reveal their upper surface only in flight.  Males and females can look quite similar, but the males will often be the more vibrantly colored of the two.  



In central Texas we have three common hairstreak butterflies.  The largest, as indicated by its name, is the Great Purple Hairstreak (Atlides halesus).  Dusky purplish-black below and brilliant blue above with red spots near the base of the wings and a bright orange abdomen, this butterfly flies spring through fall.  It tends to stay well above the ground, and males will sit on trees on hill summits or flat plains to await females, mostly in the afternoon.  Its larval foodplant, or plant upon which the female lays her eggs, is mistletoe species in the genus Phoradendron.  


Great Purple Hairstreak, Atlides halesus 

Another commonly encountered hairstreak is the Gray Hairstreak (Strymon melinus).  It has only one tail on the hindwing and an upperside that is blue-gray with a large reddish-orange spot near the tail.  The male's abdomen is orange and the female's is gray.  In the spring and fall its underside is dark gray, and paler gray in the summer, but it always has a dashed white line, parallel and inset from the wing's edge, bordered with orange.  It flies from February to November and is the most widespread hairstreak in North America.  Males perch all afternoon and into evening on small trees and shrubs to seek receptive females, who lay eggs one at a time on a wide variety of plants including peas, mallows, beans, clovers, and cotton.  



Gray Hairstreak, Strymon melinus

One of our most beautiful hairstreaks is the Juniper Hairstreak (Callophrys gryneus), belonging to a group called Evergreen Hairstreaks, which are widespread and variable.  The upperside of the male is dark brown with an olive-colored sheen, and the female is blackish brown.  Their underside is a vibrant green with two white spots near the base of the forewing and an irregular white line edged inwardly with a reddish-brown.  Males perch on host trees, those in the genus Juniperus like our native Ashe Juniper, awaiting females.  They perch with their wings closed and blend into the junipers so well that they may not be noticed until moving branches cause them to fly.   


Juniper Hairstreak, Callophrys gryneus 

When it comes to survival, hairstreaks have developed an interesting adaptation, much of which has to do with their tails.  Often having distinct markings or spots near these tails, together they form what is known as a 'false head' with the tails looking like antennae.  The illusion is carried further when the hairstreak performs a back-and-forth 'sawing' motion with the hindwings when resting. This motion can distract would be predators such as spiders, causing them to attack the wrong end of the butterfly, leaving the vital structures intact.  



Missing tails and part of the lower portion of the hindwings does not hinder flight, and the butterfly lives to carry on another day.  So it really is true that two heads are better than one!