Rosenberg's Gladiator FrogBoana rosenbergi

Rosenberg's Gladiator Frog (Boana rosenbergi) is one of the largest treefrog species in Central America.   It has a body length of 3-4 inches as an adult.   Although they are not as heavy bodied as some of the Leaf Frogs and Monkey Frogs, they are a very "long" frog.  

Although this is a rainforest species, this frog is quite adaptable and will breed in artificial ponds and similar water sources in rainforest clearings and even residential areas.   These frogs in this recording were living in the weedy margins of an artificial pond surrounded by grass on the grounds of the Esquinas Rainforest Resort in Gulfo Dulce region of Costa Rica.   These frogs called most evenings whether it rained or not.

I wish I had better photos of this species that this one photo from the road, but it was POURING rain when I came across this frog one night on the road I was walking.  I didn't have my camera with me due to the torrential rain.   I also wasn't motivated to spend time to pose it for a better "phone photo" because both my raincoat and hat had already become saturated and I was worried about my recording gear getting wet.   I know, lame excuse! 😢

Like some of the other big Boana treefrogs, the call of this species is dry and course and quite percussive.  It is a two part "tok-tok" call that reminds me quite a bit of the similarly large Australian White-lipped Treefrog (Nyctimystes infrafrenatus), even though the two species are not closely related.

If we take just a short section of that recording and look at the spectrogram, we see the individual pairs of percussive strikes. (The recording is below the image if you want to hear it).

Notice that, once again, when two frogs are chorusing together, one individual will alter the pitch of its call to avoid being masked. So we hear a distant double call, then our main "actor" gives his two "toks", followed by another frog's two "toks" then the main frog calls again.  In this case the second frog has used a lower frequency call and you can see that in the height of the bars of the second set of calls compared to the first frog's call.  They aren't quite as high because the call is lower pitched to help distinguish them from each other.