Western Narrow-mouthed Toad
Gastrophryne olivacea

The Western Narrow-mouthed Toad (Gastrophryne olivacea) is a common resident of central and southern Texas but is generally overlooked by most people.  This is because it is usually found underground or under rocks and other surface cover.  It only comes to the surface to breed after heavy rains.

This group of anurans is a clear example of the problem of using common names to categorize animals.  The old rule every elementary school child was taught was that "frogs have smooth skin, toads have dry skin" or that "frogs live near the water, toads live further away".  Unfortunately, those rules only work for two of the almost 50 Anuran families that are currently recognized.  
In this case, we have a a family of smooth skinned animals that live away from the water yet some of the members of this family are known as frogs (Sheep Frog) and others are known as toads (Narrow-mouthed Toads).

Narrow-mouthed Toads have a conspicuous fold of skin just behind the eyes and a short, pointy head and fat body.
The underside of this species is uniform white or gray, which distinguishes it from its eastern cousin, the Eastern Narrow-mouthed Toad (G. carolinensis).  The Eastern species has a black and white mottled belly.

Narrow-mouthed Toads are small frogs.  Females reach approximately 1.5 inches while males are even smaller.   Males also have a black throat.

Narrow-mouthed Toads tend to call from flooded grassy fields and ditches after heavy rains.  The frog shown above was calling from a shallow puddle of water in a flooded lawn in Comal County, Texas.

They usually call either floating with their legs extended or standing upright among grassy pond edges as seen here.  Their vocal sac is quite large for such a small frog.

Their call is a surprisingly loud, nasal, bleating "waaaaaahhh".  It is one of the conspicuous sounds in southern Texas after heavy rains.

Here is the recording of the individual in the photo -

Here is the spectrogram from a single call from that frog.
You can see that there is a increase in pitch at the beginning followed by the long, wide band bleat.

Large choruses of these little frogs can make a constant buzzing sound.  Here's a large chorus from La Salle County, Texas.

Individual calls can be distinguished by the slight upward whistled slur that the frogs make in while in large choruses.  This large chorus in La Salle County, Texas shows that pattern.

Here's a short section of that chorus:

and the spectrogram for that section.  The sold dark area around 4-5 KHz is the buzzy nasal whine of the Narrowmouthed Toads.  The highlighted upward slurs represent where a individual frog starts a new call.  You only see/hear this in large choruses of these frogs.

© Chris Harrison 2012

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