Winter Chorus Frogs

If you live in the southeastern U.S., you’re probably used to the discrepancy between the timing of the seasonal changes that you observe and the "official" dates on your calendar.  During the winter, temperatures often climb to the 80s; brightly-colored flowers dot the lawns; resident birds start to seek out nesting territories in the woods and fields; and snakes, turtles, and (in some areas) alligators begin to stir in lakes and ponds.  Breeding frogs, taking advantage of the rain and the warmer temperatures, also put in appearances during this period.  While many frog species in the southeastern states hibernate through the winter and are not active until March or April, a few are commonly heard calling before the trees leaf out.  If you live in Mississippi, the species that you are most likely to encounter during the winter are chorus frogs, members of the Pseudacris genus.

The spring peeper (Pseudacris crucifer) is probably the most abundant of these “winter” chorus frogs.  I would venture to say that most people in the southeast are very familiar with the piping call of this tiny amphibian, but for those who aren’t (or those who would like a refresher), the U.S. Geological Survey has a recording.  From around late January to early April in Mississippi, you might hear this distinctive call in almost any wooded habitat near water.  Spring peepers spend much of their time in dense vegetation near the ground, so they are difficult to see—beneficial for them, but a pity for us, because they have very pretty, if subtle, patterns: dark brown leg stripes and a dark-brown x-shaped marking on a lighter brown background.  The camouflaging coloration and retiring habits are useful predator-evasion adaptations.

A close relative of the spring peeper, the upland chorus frog (Pseudacris feriarum) is fairly common in winter.  Despite their name, upland chorus frogs can be found in both lowland and upland habitats.  I would suggest listening for them in areas that are more open than the typical spring peeper habitat; old pastureland, fields, and meadows near sources of water are good places to check.  The trilling call of the upland chorus frog somewhat resembles the sound made when you run your thumb over the teeth of a metal comb.  In Mississippi, I have heard this species as early as the middle of December, and it may breed until April.  Like spring peepers, upland chorus frogs are secretive and extremely hard to spot.  One of their diagnostic field marks is a pale stripe above the upper lip, just below the dark stripe that extends behind the eye.  

Upland chorus frog - mixed-media painting

It’s worth pointing out that, in recent years, the range limits of the upland chorus frog and the very similar Cajun chorus frog (Pseudacris fouquettei) have been reevaluated.  Both species are found in Mississippi, but it’s likely that the Cajun chorus frog is restricted to the western portion of the state, while the upland chorus frog occurs farther east.  The call of the Cajun chorus frog is slightly slower than that of the upland.  

Happy listening!


Sources

The IUCN Red List of Threatened Species, http://www.iucnredlist.org/
USGS Frog Quiz, https://www.pwrc.usgs.gov/frogquiz/index.cfm?fuseaction=main.lookup
Wildscreen Arkive, http://www.arkive.org/upland-chorus-frog/pseudacris-feriarum/