A Water Dance of Grebes

Eared Grebe in winter plumage, lacking the characteristic and showy golden ‘ear’ feathers.

Winter is one of the best times to observe waterfowl in central Texas. Several species spend the colder months on our quiet lakes, reservoirs, and ponds, searching for food in the open, unfrozen waters.  One interesting family that can be seen this time of year are the grebes, aquatic diving birds known for their strong swimming, but not often seen on land or in flight.

Grebes are not ducks, although both are considered to be waterfowl.  They lack webbed feet like ducks, and instead have lobed toes.  Their legs attach further back on their bodies than ducks, making it supremely awkward for them to walk on land. Combined with their lobed toes, however, these attributes make them powerful swimmers and divers for their size.  In our area, there are three species of grebe that can be observed, the Pied-billed Grebe (Podilymbus podiceps), the Least Grebe (Tachybaptus dominicus), and the Eared Grebe (Podiceps nigricollis).

Pied-billed Grebe

The Pied-billed Grebe is a small but chunky waterbird 13.5 inches long that is brownish overall with a blocky head, short thick bill, and almost no tail.  During breeding season, its pale bill has a vertical black stripe, which gives it its name as ‘pied’ means having two or more different colors.  These grebes can trap water in their feathers, giving them control over their buoyancy, sinking deeply or exposing as much or as little of their body as they wish. The Pied-billed Grebe is present year-round, but are more abundant from mid-September to mid-May.  They are not gregarious, so they are often solitary or found in very small groups.

Least Grebe

Least Grebes arrive in central Texas in mid-September, but become scarce by early February.  As the smallest grebe in North America at 9.75 inches long, they have golden yellow eyes, a slim dark bill, are purplish gray in summer, and overall gray brown with a whitish throat and paler bill in winter.  Rather uncommon or local, they can sometimes hide by submerging their entire body under water with only their bill visible.  The Least Grebe is light and has large wings relative to its size, so it can take flight from the water more easily than most other grebe species.

Unlike the previous two grebes, the Eared Grebe is the most abundant grebe species in the world, but it is largely a winter resident in Texas, typically appearing by October and disappearing by May.  It is also a small waterbird at 12.5 inches in length with a bright red eye, very thin bill, and overall dusky brown with white.  In their summer range further north and west, they are black with chestnut sides, and sport golden ‘ears’ or wispy feathers that fan out noticeably from their cheeks behind their eyes. Eared Grebes migrate only at night, and their southward migration in the fall is the latest of any bird species in North America.

The collective noun for a group of grebes is a ‘water dance’, which refers to the fact that they have some of the most elaborate courtship displays of all birds.  Often described as ballet-like, these displays can include bowing, feather fluffing, and rising up nearly out of the water, extending their necks and appearing to run across the water’s surface.  Displays vary and can occur between mated pairs or two competing males, suggesting that they have multiple functions.

Get out this winter and scan the open waters for these beautiful little birds.  While they are not particularly common, nor do we normally see them in the height of their breeding plumage, they are still standouts among the typical rafts of ducks that overwinter in our area. 

Christmas Cactus

The bright red fruits of Tasajillo are present at holiday time, giving 
it an alternate common name of Christmas Cactus.

While many people are familiar with the tropical, non-native species of Christmas Cactus (Schlumbergera sp.) often sold as houseplants, not all are aware that we have a native Christmas Cactus (Cylindropuntia leptocaulis) here in Texas.   Our Christmas Cactus, also called Tasajillo, Pencil Cactus, Christmas Cholla, and Desert Christmas Cactus, is a true cactus much more adapted to our types of soils and climate. Common in the central and western parts of Texas, this plant’s species name, leptocaulis, means ‘slender-stemmed’, and it is a very good descriptor of its form.

Unlike many other cactus species, the flower of our native Christmas
Cactus is small, at only one half-inch across.

Upright, shrub-like, with many branches made up of slender, cylindrical jointed segments, this 2 to 5 foot tall plant is most often found growing in sandy or bottomland soils, having a trunk or main stem up to 4 inches in diameter with thicket-forming stems that exhibit various shades of green and feature a solid, woody internal core.  While occasionally spineless, it typically has very slender, 1-inch grayish-white spines grouped with much tinier spines, along each stem.  Botanists now think that two forms grow in Texas, a ‘long-spine’ form and a ‘short-spine’ form. Its leaves are very small, often not even noticed before they fall early in the growing season.  Small, pale, yellow-green flowers appear at irregular intervals in April/May and July/August, opening in late afternoon or evening.  But the true color display occurs in December, when its fruits turn conspicuously bright red and seemingly cover the plant like it has been festooned for the holiday season.

Christmas Cactus, short-spined growth form.

Christmas Cactus can grow from seed, but it is much more likely to spread by cloning.  The jointed stems can easily detach without harming the rest of the plant, and they are dotted with areoles, a structural feature of cacti that contain buds. All a stem needs to do is come in contact with the right soil, and it can take root and grow a whole new plant.

Christmas Cactus, long-spined growth form.

While the Christmas Cactus can be a nuisance if it develops in the wrong areas, it can also provide desirable value to wildlife and to humans.  Growing best under the protection of other vegetation, it offers dense cover for a variety of nesting birds and provides a good food source for white-tailed deer, bobwhite, wild turkey, most bird species, and many small mammals.  In West Texas, this plant is a larval host plant for the beautiful Staghorn Cholla Moth. From a human perspective, Christmas Cactus has a good ornamental value in a mostly xeric landscape, as it stands out in the bleak winter landscape, adorned with red fruit when most other vegetation is bare.

Staghorn Cholla Moth

Several sources describe the fruits of the Christmas Cactus as edible, even intoxicating.  But they are so small, and the spines so troublesome, that the plant usually yields only a sporadic nibble to the curious human. Nevertheless, native tribes made it part of their traditional diet, noting that the fruits, also called tunas, are vaguely sweet with a taste similar to the fruit of a prickly pear cactus.

Take the time to get to know our native Christmas Cactus and consider adding it to your wildscape.  You will easily learn to fall in love with its prickly nature, especially at Christmas time!

Frost Flowers

Blooming from August to November, Frostweed provides late season nectar
and a unique surprise at the first frost.

Accompanying the crunching of fallen leaves and the rattling of seed pods drying in the breeze is the arrival of the first frost.  This marks the seasonal change from our relatively warm autumn to the cooler days of a mild central Texas winter.  How does frost, this sparkling layer that sometimes covers the fall landscape, form? 

When the temperature of the air reaches a point where the water vapor in it can condense out into water, it is called the dew point.  The frost point is when the dew point falls below freezing, and rather than producing dew, it creates frost.  Consisting of tiny, spike-like crystal structures called spicules that grow out from a solid surface, frost generally forms on surfaces that are colder than the surrounding air.  Even the size of the crystals can vary, depending upon the amount of time they took to grow, the relative changes in temperature, and the amount of water vapor available. 

A frost flower.

Cold air is denser than warm air, so quite often lower areas become colder on calm nights due to differences in elevation.  Known as surface temperature inversion, this phenomenon forms ‘frost pockets’ or areas where frost forms first, due to cold air trapped against the ground.  It is here, in these areas, that you can find a rare and wonderful spectacle of nature called ‘frost flowers.’

While many plants can be damaged or killed by freezing temperatures or frost, this varies by the type of plant and tissue exposed to these conditions.  In central Texas, there is a common plant called Frostweed (Verbesina virginica), which is found in low-lying areas near streams, creeks, canyon bottoms, and in dappled shade at woodland edges. 

Bordered Patch

Silvery Checkerspot

Much of the year, Frostweed goes unnoticed while it grows 5 to 8 feet tall and leafy, the top of each stalk crowned by a cluster of small white flowers.  Its stalks are oddly square-like, with fleshy green flanges. Frostweed begins to bloom in the August heat, and continues until first frost, well into the fall.  These flowers provide late-season nectar for many insects, including bees, beetles, flies, wasps, and even migrating hummingbirds and Monarch butterflies.  It is also a host plant for Silvery Checkerspot and Bordered Patch butterflies.

A patch of frost flowers.

With the first frost, however, the water contained in each Frostweed plant stem expands, causing the stems to crack.  Via capillary action, more water is drawn through the cracks, freezes when it hits the cold air, and forms long curls of ice like petals of a flower, ribbons, or other delicate, abstract sculptures.  Most often, they consist of longitudinal bands of fine ice threads at right angles to the stem.  These delicate flowers of the frost are fleeting in nature, and can only be found in early morning, as the rising temperature quickly melts them away. 

A prime example of crystallofolia.

Only a few species of plants exhibit this unique phenomenon, which has been called ‘crystallofolia’ by Bob Harmes at the University of Texas, from the Latin crystallus or ‘ice’ and folium or ‘leaf’.  Much is left to be discovered reading the purpose of this process, but further research by Dr. James Carter at Illinois State University has concluded that the ice formation often far exceeds the amount of moisture locally available within the plant’s stem, so it must be augmented by water drawn up from the roots.

Delicate curls can form when more plant moisture is available.

On the surface, fall may seem as if nature is shutting down for the winter, but take the time for a second look and you just might be surprised.  The first frost of the season is another intriguing part of the ongoing cycle of life and renewal for our native plants and animals.

A Parade of Pollinators

Fall-blooming plants like Goldenrod attract a variety of insect pollinators.

Much has been written lately on the importance of pollinators, as they are vital to creating and maintaining the habitats and ecosystems that many animals (and humans!) rely on for food and shelter.  In fact, more than one in three bites of food we eat or beverages we drink are directly dependent on the success of pollinators. While most people think of bees as the primary pollinators, or even charismatic groups such as butterflies and hummingbirds, pollinators also come in the form of wasps and flies.

This time of year, you can find many of these bees, wasps, and flies nectaring on and pollinating our fall-blooming plants.  Aside from the well-known but non-native European Honey Bee, other native bee species that are still around this time of year include the Metallic Epauletted-Sweat Bee (Augochloropsis metallica), American Bumblebee (Bombus pensylvanicus), Southern Carpenter Bee (Xylocopa micans), Parkinsonia Carpenter Bee (Xylocopa tabaniformis parkinsoniae), and Texas Carpenter Bee (Xylocopa virginica texana).

Metallic Epauletted-Sweat Bee

The uncommon Metallic Epauletted-Sweat Bee is a small bee, to 0.5 inches, overall metallic green with distinctive scale-like coverings at the base of each amber-colored veined wing.  It nests in soft ground, and is especially attracted to asters, grapes, and legumes.  

American Bumblebee

The American Bumblebee is common and robust, to 1 inch, with a thorax yellow in front and black in back, an abdomen with the first three segments yellow and the rest black, and mostly black veined wings. Once abundant, populations have declined significantly in recent years, and it is listed in Texas as a species of ‘greatest conservation need.’

Carpenter bees are typically separated from bumble bees by their big, shiny abdomens.  They bore into the surface of wood to build their nests, often leaving a small pile of sawdust underneath. Due to their large size and heaviness, carpenter bee species often perform what is called ‘nectar robbing’, using their mouthparts to bite through the base of tubular flowers to access nectar rather than entering the flower directly.

Southern Carpenter Bee

The uncommon Southern Carpenter Bee is large, to 1 inch, with the female being shiny blackish overall and the male more of a glossy dark greenish-blue, both with smoky veined wings.  

Parkinsonia Carpenter Bee, nectar robbing

The more common and endemic Parkinsonia Carpenter Bee is a bit smaller at 0.8 inches, overall blackish, with males having gray-blue eyes and females with dark blue eyes, both with a black abdomen with four distinct yellow bands on each side that do not meet in the middle, and smoky veined wings. 

Texas Carpenter Bee, nectar robbing

Also common is the Texas Carpenter Bee, to 1 inch, with a thorax covered in yellow hairs except for a round black spot on top, a shiny black abdomen, and smoky veined wings. 

Blue-winged Scoliid Wasp

Wasps differ from bees in that they are smooth, shiny, and often slender or narrow-waisted. The Blue-winged Scoliid Wasp (Scolia dubia) is an uncommon native wasp, to 1 inch, overall black with a mostly reddish abdomen (sometimes with a large yellow spot on each side), and dark blue veined wings. Adults provision their nests with beetle larvae, commonly of Green June Beetles. 

Fraternal Potter Wasp

The Fraternal Potter Wasp (Eumenes fraternus) is an uncommon native, to 0.8 inches, overall black with an elongated but swollen waist, a bulbous tapering abdomen, with an ivory stripe behind the head and some before the waist, two ivory side spots and a stripe near the abdomen’s tip, and dark amber-brown veined wings. Females fashion unique, marble-sized urns of mud as nests, one for each egg, and provisions them with small caterpillars.

Potter wasp nest

While many view flies as pests, flies are actually second in importance to bees as pollinating insects.  Flies pollinate more than 100 cultivated crops such as cocoa, strawberries, apples, blackberries, peaches, onions, parsley, and carrots.  A large number of wild native plant species, including many medicinal plants, are aided from fly pollination as well.  In our area, two interesting fly species are the Oblique Stripetail Fly (Allograpta obliqua) and the Four-speckled Hover Fly (Dioprosopa). Both are native but uncommon, most often seen through November on a wide variety of flowering plants with or near aphid colonies.

Oblique Stripetail Fly

The Oblique Stripetail is a small fly, to 0.3 inches, with reddish-brown compound eyes, transverse bands on a dark abdomen with four longitudinal yellow stripes near the tip, and clear veined wings. It is a member of the hover fly family, having the rare ability to hover or fly backward.  

Four-speckled Hover Fly

The Four-speckled Hover Fly is a bit larger, to 0.5 inches, with dark brown compound eyes, a black abdomen with two pairs of whitish speckles or dashes, and a pair of clear veined wings with a brown leading edge.  Its larvae eat aphids, and this fly is considered to be a wasp mimic, due to its thin, ‘wasp-waisted’ abdomen.

The species shown above are only some of the many distinctive species of bees, wasps, and flies that are important pollinators. This fall, take a closer look at the insects that are busy nectaring on your plants, and pollinating them in the process. Make a difference to their populations by adding a wide variety of native plant species in your yard that bloom from spring to fall, and be sure that you avoid using pesticides.  Your actions alone can help promote a healthy parade of pollinators for many months of the year, that in the end benefit us all!

False Foxgloves

 

Plateau Agalinis, endemic to the Edward's Plateau.

Not much is known about the genus Agalinis, a group of about 70 plant species found in North, Central, and South America. They are partially parasitic or hemiparasitic plants that can make food through photosynthesis, but only after siphoning water and mineral nutrients from a host plant, in this case a variety of different hosts but most typically grasses. They do this by growing haustoria, or a root-like structure that connects their roots to the roots of their host.

Detailed studies of this perplexing genus are few and far between, and little else is known about each species, including who are their pollinators and what are their accurate historical and current geographic distributions.  In fact, many species are rare or endemic to a particular area or even federally protected.  Of the 34 species in the US, two are found in central Texas, and they are both some of our showiest fall bloomers.

Prairie Agalinis has a very short stalk attaching it to the stem.

Prairie Agalinis (Agalinis heterophylla), also called Prairie False-Foxglove, is an erect, airy herb, to 2.5 feet tall, with opposite, simple, narrowly linear leaves to 1.25 inches long. Its 5-lobed, bell-shaped flowers, pink to lavender-tinted white with purple-red spots in the throat, are 0.75 inches long and arise from the stem on 0.1-inch long stalks.  It is common in the eastern half of Texas, blooms from September to October, and is found in open floodplains, prairies, stream edges, and creekbanks.

Plateau Agalinis has a much longer stalk attaching it to the stem.

Easily confused with Prairie Agalinis is Plateau Agalinis (Agalinis edwardsiana), also called Plateau False-Foxglove and Plateau Gerardia, an uncommon and endemic species found in the grasslands and open woodlands on rocky limestone slopes in about 12 counties on the Edwards Plateau. It can grow to 3 feet tall, with very similar narrow leaves and pink to rose-colored flowers as A. heterophylla, but its flowers arise from the stem on much longer, 1.25-inch stalks. It blooms from September to November, and is a host plant and nectar plant for the Common Buckeye butterfly.

Common Buckeye

Left alone, both of these species will develop small, spherical capsules that burst open when dry, releasing several tiny seeds that will develop into next year’s plants. These native fall-bloomers are airy, delicate-looking plants that can easily survive dry soils, and bring much needed color to rocky, limestone areas or the edges of our ephemeral creeks and streams. In fact, their genus name comes from the Greek aga- an intensifying prefix meaning ‘large or great’ and New Latin   -linis meaning ‘flax’, referring to their superficial, flax-like resemblance. Look for them when the weather begins to cool, and enjoy their attractive, abundant blooms from late summer into fall!

A Killer of a Wasp

In late June and July, cicadas begin emerging from the ground,
breaking  through their shells or exuviae,
leaving the empty husks behind.

What are those large, solitary wasps we see flying around our yards from late June to September?  Often referred to as the Cicada Killer or Cicada Wasp (Sphecius speciosus), this native species occurs in the eastern and midwestern U.S. regions, southwards through Texas into Mexico and Central America. Cicada killers are so named since they prey on cicadas and provision their nests with them.  While large and intimidating, they offer a measure of natural control on cicada populations.  They benefit our native plants by pollinating flowers and protecting trees from the numerous cicadas that feed on their roots and foliage.

Cicada Killer or Cicada Wasp nectaring at a flower.

Cicada killers are robust wasps up to 2 inches long, with amber wings and black to reddish-brown abdomens with yellow stripes.  The females are somewhat larger than the males, and both are among the largest wasps in the U.S. These solitary wasps have a very unusual and interesting lifecycle.  Females are commonly seen skimming around areas with sparse vegetation for nesting sites, burrowing a tunnel, 10 to 20 inches deep, in dry or bare soil.  In digging a burrow, she will dislodge the soil with her jaws, and using her hind legs that are equipped with special spines, push the loose soil behind her as she backs out of the burrow. 

Cicadas, like this Megatibicen resh,
are hunted by the female Cicada Killers.

The female cicada killer proceeds to capture cicadas, sometimes even in flight, paralyzing them with her venomous sting.  She places the cicadas beneath her, grasping them with her legs, and either flies or drags her prey, which is twice her weight, into her burrow.  After placing a few cicadas in her nest, she begins to lay her eggs.  Females can predetermine the sex of the egg, and she lays multiple male eggs on a single cicada.  But each female egg is given 2 or 3 cicadas, as females are larger, require more food, and more females are needed to create new generations.  Eggs are always laid under the left or right second leg of the cicada. The female then closes the burrow with dirt, as the eggs hatch in a few days, but the larvae take some time to mature, feeding on cicadas as they overwinter in their burrow, not emerging as adults until the following spring.

Adult male cicada killers emerge in spring before the females, defending the territory around their emergence hole and searching for females.  They typically perch on the ground, flying up to attack any rival males. Once females emerge, mating occurs, and the males die shortly after.  Females live long enough to dig and provision their nests, and die after laying all of their eggs.

Cicada killer wasps are not aggressive toward humans and rarely sting unless provoked by grasping them roughly, accidentally stepping on them, or if caught in clothing.  Only the females have stingers, and while males will actively defend their perching areas against other males near nesting sites, they have no stingers. Both males and females have large jaws, but they are not known to grasp human skin and bite.  If swatted at, they will just fly away rather than attack. They are simply focused on cicadas or other cicada killers!

Evening Chorus

Green Tree Frog

From late winter into early summer, many of the night sounds you hear are not insects at all, but members of a wide-ranging group of cricket, tree, chorus, and chirping  frogs.  This group of frogs and their allies have adaptations that reveal their mostly arboreal lifestyle, such as forward-facing eyes for binocular-like vision, adhesive pads on their fingers and toes, and a fondness for eating insects.  Often not seen due to their diminutive size, these frogs are commonly mistaken for insects, due to their ability to produce loud and varied mating calls.  Known as ‘advertisement calls’, these calls are produced by the males to attract females and warn other rival males during the breeding season.

Blanchard's Cricket Frog

At ½ to 1 ½ inches, Blanchard’s Cricket Frog (Acris crepitans blanchardi) is found throughout most of the state, except for the Panhandle and West Texas.  Gray to green-brown, this frog has a long rounded snout, dark bands behind its limbs, and a distinguishing triangular patch behind the eyes that points down its back. Diurnal and active all year, these frogs prefer shallow but permanent ponds with vegetation and full sun.  Often seen basking during the daytime, they will jump quickly into the water or away when disturbed, and are capable of covering 6 feet in one leap!  Although they are part of the tree frog family, they are much more terrestrial and are excellent swimmers.  When chorusing, especially at night, the male’s call sounds like clicking small rocks or pebbles together.  Mating occurs in late spring, with the female laying one egg at a time on submerged vegetation.

Green Tree Frog

The Green Tree Frog (Hyla cinerea) is a common, 1 to 2 inch frog with a slender, bright green body, cream-colored belly, and white lips that extend into lateral stripes along the sides of its body.  Found in the eastern third of our state, this frog walks rather than jumps when on the ground.  It is nocturnal, and prefers wet areas such as swamps, edges of lakes, and stream sides.  During its breeding season from March to October, the males start calling just before dark, and sound like groups of tiny ducks quacking.   Females, which are slightly larger than the males and lack the wrinkled vocal pouch, lay their fertilized eggs enclosed in a jelly envelope attached to floating vegetation.   Influenced by the weather, breeding often takes place during or after a rain.

Cliff Chirping Frog

At ¾ to 1 ½ inches, the nocturnal Cliff Chirping Frog (Syrrhophus marnockii) is found in the cracks and crevices of limestone cliffs.  Mostly green with brown mottling and dark crossbars on its hind limbs, this frog also has a proportionately large head and big eyes.  It can run, leap, and hop, and its flattened body allows it to slip into cracks in the rocks to avoid predators.  Sounding a bit like a shy cricket, the call of the Cliff Chirping Frog is a series of short, clear chirps and trills.  While calls are made throughout the year, they are sharper and clearer when females are present.  From February to December females may lay eggs as many as three times in moist leaf litter or soil, although peak breeding occurs in April and May.  

When you’re out at night from winter to late spring or early summer and near one of our natural areas, sit quietly and in no time you should be able to identify the unmistakable sounds that make up the evening chorus!