Breaking Slumber

 

Many small creatures awaken in Spring

In the winter months in central Texas, most cold-blooded reptiles and amphibians exhibit a form of hibernation called brumation. Triggered by shorter days and lower temperatures, this state can last for days or weeks, depending on the species. Brumation differs from true hibernation in that these animals remain semi-conscious and occasionally wake up to drink but not eat. During this period, body temperature, heart rate, and respiratory rates are greatly reduced.  This state of dormancy occurs with several common amphibian species, including the Rio Grande Leopard Frog (Lithobates berlandieri), Gulf Coast Toad (Incilius nebulifer), and Green Tree Frog (Hyla cinerea).

Rio Grande Leopard Frogs are medium-sized native frogs, to 4.5 inches, greenish-brown in color with a yellowish ridge along each side of the back. They have large dark spots on the back and sides, and a wide, light-colored jaw stripe that is poorly defined and fades in maturity. Their call is described as a short, low-pitched guttural rattle, either given singly or in rapidly repeated sequences. These frogs spend the winter months resting at the bottom of ponds, lakes, or other bodies of slow-moving water, but can become active during warmer, wet periods. Since they are semi-aquatic, they can also tolerate cold conditions by burrowing into mud or soil. They tend to enter brumation just before freezing weather, and often hide in deeper water to temporarily escape extreme temperatures.

Rio Grande Leopard Frog

The Gulf Coast Toad is a native, broad-headed, mostly terrestrial toad, to 5 inches, with prominent cranial crests that form a depression on top of the skull. Their background color is brownish-yellow to brownish-gray, with broad dark lateral stripes bordered by a light stripe, as well as a light central stripe, and they are covered in numerous small whitish to orange spots. Their vocal sac becomes large and rounded when calling, which sounds like a short, flat trill repeated several times. These toads are usually dormant from December to February, hunkering down in self-dug holes, abandoned animal burrows, under logs, or in leaf litter to protect themselves when the temperature dips below freezing. While they become active as the temperatures rise in early spring, they may also burrow to survive hot, dry conditions in the summer months, and this unique behavior is called aestivation.

Gulf Coast Toad

Green Tree Frogs are smaller, native arboreal frogs, to 2.5 inches, with smooth skin, a slender, flat body, and long slender legs with large toe pads on each foot. In warmer conditions, when the frog is active, they are typically a bright green color, but they can change to a dull color during periods of cool weather or to blend in with their surroundings. They also have a long white stripe on either side of the body. Their call sounds vaguely like a honking duck and is repeated 30 to 60 times a minute. These frogs brumate in the winter months, often hiding under deep leaf litter, in tree cavities, in potted plants, or even in the corners of garages and sheds. During this time of inactivity, they slow their metabolism and sometimes survive partial freezing by producing natural antifreeze compounds called glycerol that protect their cells. They also typically choose sheltered damp spots to avoid freezing completely, and may wake on warmer, sunny winter days to move about.

Green Tree Frog

As the days get longer and temperatures begin to rise, once again we will be treated to the sights and sounds of these marvelous amphibians, as they break their winter slumber!

Winter Chorus

Clear and bell-like, consisting of a single, quickly repeated note, the call of the male Strecker’s Chorus Frog (Pseudacris streckeri) is unmistakable.  In the midst of winter, especially in the peak calling season from January to early March, multiple males call at the same time, their alternating notes resulting in an unexpectedly delightful winter chorus rising up from the canyons!

Reaching an adult length of 1 to 1.5 inches, this largest chorus frog is identified by a stout gray, brown, olive, or green body, a dark brown mask-like stripe through the eye and a dark spot under the eye, dark longitudinal stripes along the back, and a deep golden or orange color in the groin. Males are slightly smaller than females and have greenish-yellow vocal sacs.  The genus Pseudacris comes from the Greek pseudes meaning ‘false’ and akris meaning ‘locust’, and is likely a reference to the repeated rasping calls of most chorus frogs, which are similar to and can be mistaken for those of an insect.

Although Strecker’s Chorus Frog is mainly a nocturnal frog, its call can be heard day or night. Males call as they hang on to or sit on vegetation, or from the bank above the water’s surface. Typically feeding on insects, this chorus frog is seen most often in moist woodlands, rocky ravines, near streams or in swamps.  While its range includes portions of Kansas, Illinois, Missouri, Oklahoma, Arkansas, and Louisiana, the individuals in Texas are of the subspecies P.s. streckeri, and occur in most counties in the eastern half of our state.

Aside from its distinctive winter chorus, Strecker’s Chorus Frog is also distinguished by its ability to use its forelimbs to burrow headfirst, unlike other amphibians that typically use their hind legs to back into a burrow.  It burrows deeply in sand or mud and hides under rocks and woody debris to protect itself from heat and predators, emerging mainly after heavy rains. Following these rains, it migrates a short distance to a preferred breeding site.

Strecker’s Chorus Frog is a cold-tolerant, winter breeding frog, breeding anytime between November and March when rains are adequate. While most frogs prefer to breed in flowing water, Strecker’s Chorus Frog prefers still, clear, temporary water bodies such as ditches, ponds, and pools in wet weather creeks.  Females attach their small, jelly-covered clusters of eggs to vegetation below the water’s surface, and the time to hatch, while water temperature dependent, is usually just a few days.  Tadpoles take around two months to transform into adult chorus frogs.  In spring, at a time when most other frogs are just beginning to seek their breeding ponds, Strecker’s Chorus Frogs terminate their breeding activities.

Named after John Kern Strecker, Jr (1875 – 1933), a Texas naturalist and Curator of the Baylor University Museum (renamed the Strecker Museum in 1940 in his honor), this chorus frog with its peculiar and unusual habits and haunting winter chorus might have been a perfect candidate for “Strecker’s Cabinets of Curiosities”!  

If you’d like to see and hear the chorus for yourself, check out the video at https://texaswild.me/2014/03/31/streckers-chorus-frogs-calling/