Lifelist Update for January 2019

Spent Christmas 2018 on a holiday trip to Trinidad and Tobago.  Didn't spend much time recording frogs but I did get to add a few species to my recording lifelist.

Eastern Glass Frog (Hyalinobatrachium orientale) - new species (added in July)
Mount Tucuche Tree Frog (Flectonotus fitzgeraldi) - new species (added in May)
Smooth-skinned Ditch Frog (Leptodactylus validus) - new species
Whistling Grass Frog (Leptodactylus fuscus) - new species
Trinidad Poison Frog (Mannophryne trinitatis) - new species
Tobago Poison Frog (Mannophryne olmonae) - new species
Urich's Leaf Litter Frog (Pristimantis urichi) - new species
Rusty Treefrog (Boana boans) - new species

So, a bit of updating to the lifelist means it looks like this....


Family Genus Number of species recorded so far
Bufonidae

Anaxyrus
10

Incilius
3

Rhinella
2

Hylidae

Acris
3

Boana
1

Dendropsophus
1

Hyla
8

Pseudacris
6

Osteopilus
1

Scinax
2

Smilisca
2

Triprion
1
Pelodryadidae

Litoria
6

Nyctimystes
1

Ranoidea
4
Microhylidae

Austrochaperina
2

Hypopachus
1

Gastrophryne
2
Myobatrachidae

Crinia
1

Limnodynastes
2
Craugastoridae

Craugastor
1

Pristimantis
1

Eleutherodactylidae

Diasporus
1

Eleutherodactylus
9
Centrolenidae

Hyalinobatrachium
2
Leptodactylidae

Leptodactylus
6
Ranidae

Lithobates
8
Dendrobatidae

Oophaga
1
Hemiphractidae

Flectonotus
1
Aromobatidae

Mannophryne
2
Rhinophrynidae

Rhinophrynus
1
Scaphiopodidae

Scaphiopus
2

Spea
2

Total # Families = 15

Total # Genera = 33
Total # Species = 95


© Chris Harrison 2019

Tobago Poison Frog
Mannophryne olmanae


The Tobago Poison Frog (Mannophryne olmanae) is a small ground-dwelling frog found along rocky stream beds of the island of Tobago.   It has a very small range and is only known from the northeastern corner of this small island.  It is also known by the rather quaint name of Bloody Bay Stream Frog due to the fact that is found near Bloody Bay (named for a bloody battle between English soldiers and African slaves in 1771 that turned the bay red with blood!).  Tobago Poison Frog is a little less colorful but may be more descriptive of where they are found. 😉 


Unfortunately, although I was able to hear some of these little frogs calling along the roadside one afternoon, I was not able to see the individual frogs.  So the only photo I have to share is the photo of the roadside stream/waterfall area where they were calling. 😢  They were calling from above this rocky wall out of sight and inaccessible to me.

The call of the Tobago Poison Frog is a cricket-like chirping similar to the call of it's sister species from Trinidad (Mannophryne trinitatis).  When you hear them calling in a chorus like this, it sounds a bit like a squeaky metal wheel -



Next trip to Tobago, I need to actually see one of these little guys!
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© Chris Harrison 2019

Mount Tucuche Tree Frog
Flectonotus fitzgeraldi


When I'm out traveling looking for birds and herps, I often stumble across an unusual sound I don't recognize and I will record it to try and figure out if it was a new frog or something else.  

Such was the case with this frog.  I saw this tiny treefrog I saw sitting on a leaf one night while on a night walk at the Asa Wright Nature Center.  I couldn't get any closer because it was on a leaf below me on a steep hillside off the road.   So I grabbed the only shot I could.   At the time, I figured it was one of the small treefrog species from Trinidad but they are tough to ID.  So I decided to ID it later after some research.  I came up with a tentative ID of the Lesser Treefrog (Dendropsophus minutus).  

After I posted it on iNaturalist, a local Trinidad herper corrected my ID to Mount Tucuche Tree Frog (Flectnonotus fitzgeraldi).  I was delighted to be corrected not just to have the right ID, but the fact that this was one of the Marsupial frogs in a totally new family for me the Hemiphractidae!

So a few months later, I happened to be deleting some older recordings I had made with my phone and I ran across some forgotten recordings I had made in Trinidad.  I normally don't record "important" recordings with my phone but I will grab a quick recording if I don't have my other gear.   Among the recordings on my phone was this call.....


This recording included a series of buzzy clicks in patterns of two or three.  At the time I wasn't positive it was a frog, but it sounded too erratic to be a cricket or other orthopteran (they usually have long or consistently repetitive calls).  A few days ago, I happened to listen to a recording of a different Flectonotus species online (F. pygmaeus) and that made me think of this recording.   Hmm, I wonder if F. fitzgeraldi sounds similar.   There were no recordings available online, but I found this paper from about the differences between the species and I am pretty confident that the frog in my recording is Flectonotus fitzgeraldi!

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© Chris Harrison 2019

Tobago Glass Frog
Hyalinobatrachium orientale tobagoense

The Tobago Glass Frog (Hyalinobatrachium orientale tobagoense) is a small Centrolenid frog that is found only on the island of Tobago.  It is the endemic island subspecies of the Eastern Glass Frog (Hyalinobatrachium orientale) which is known from a few populations in far northern Venezuela.

I remember some 35 years ago, I saw my first photos of the glass frogs in the family Centrolenidae, I couldn't wait to get down into the tropical Americas and see one.  From my first trip into their range in 1989, it was a high priority to see one of these amazing flat-headed, clear-skinned frogs.  Several decades later and many trips to the neotropics later, I've seen dozens of species of Neotropical frogs, but never seen a single Centrolenid! 😢  And now, I have a recording of a second species which just kind of rubs it in that I can't see one of these critters.  But one day.....!

So, like some of my other recordings, I never saw this frog.  😢 
If you want to see photos of this frog and read more about it, I highly recommend John C. Murphy's excellent Herpetology of Trinidad blog!

The species is poorly known and so I can't find any recordings of its call.  Murphy et al. (2018) describe it as a high pitched "peep" given from vegetation overhanging streams.  This is the exact situation where I recorded this call, in fact it looked just like the habitat photo they show in their book for calling sites!

So, even through I've never heard this frog, I base my identification on:
1.  comparison to the calls of the other known species in the range.
2.  similarity to the calls of other Hyalinobatrachium I do know.
3.  the habitat description and description of the call in Murphy, et al. 2018.

So I guess it isn't 100% positively identified, but until someone provides me a recording of this species for comparison it will be my identification based on my research and experience.  That's the best I can do for now.

And one day, maybe, I'll actually get to see one of these amazing clear-skinned frogs!  But for now, this may be one of the only available recordings of it's call.

Tobago Glass Frog Call

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© Chris Harrison 2019

Murphy, et al., 2018, A Field Guide to the Amphibians & Reptiles of Trinidad & Tobago. Trinidad and Tobago Field Naturalist's Club
 - this is a must have book for anyone going to explore Trinidad or Tobago!
It isn't available through Amazon as I write this, but you can order it online from the T&T Field Naturalist's Club or find it in bookstores on Trinidad (which is where I found it).

Smooth-skinned Ditch Frog
Leptodactylus validus

Leptodactylus validus
Tobago
The Smooth-skinned Ditch Frog (Leptodactylus validus) is a common frog of the grasslands and forest edges of northern South America.  It is a common frog over much of its range and is often found living commensally with man.  The first group of these that I found were living in a drainage overflow that contained a few inches of water.  There were quite a few individuals living in this square drainage tank.  They were breeding and calling from the few inches of water in this tank day and night.   Although I heard and recorded them calling here on multiple occasions, I was never able to see a calling male.  I believe, like many Leptodactylus species, they were calling from beneath the mass of tangled bamboo leaves in the tank.



Although frogs are not always associated with being good "parents", many species do show some level of parental care.  Females of several Leptodactylus species have been shown to stay with their eggs and tadpoles, presumably protecting them.   I believe I observed this in the frogs in this concreted ditch as tadpoles tended to cluster around females that were sitting still in the water.


Leptodactylus validus female "tending" tadpoles
Tobago
I was able to find this species calling in more "natural" surroundings of flooded grassy fields as well as from grassy ditches at the edges of a residential area of Bon Accord in Tobago.

The call of this species is a sharp whistled "pip" or "whip".  Here are a couple of individuals calling from a grassy ditch in Bon Accord, Tobago -



Here's a look at the spectrographs of a couple of those calls.  You can see how although the call is brief, it is as ascending call with an almost "percussive" consonant on the end.




This species was often heard calling during the day.    We came across a large chorus calling from this flooded grassy area right at the junction of the main road and a busy footpath leading down to a popular tourist beach. Even though it was broad daylight and quite a few people were about, these frogs were chorusing away (hidden beneath the vegetation). 





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© Chris Harrison 2019

Trinidad Poison Frog
Mannophryne trinitatis

The Trinidad Poison Frog (Mannophryne trinitatis) is a small striped frog that is found only in Trinidad.  It is common along the edges of rocky forested streams.   It is  a relatively dark, drab frog with longitudinal stripes on the body.   It is active by day and can be seen sitting along the edge of streams on the rocks.   Unfortunately, I didn't take the time to get a better photo because I was sure I would get another chance.....I didn't.



This species is active in the day and calls by the light of day as well.  Interestingly, when this frog is calling the males darken up considerably, becoming almost black.   Here is a male calling from under the edge of a large boulder.  Again, I "planned" on coming back to this spot for a better photo after the tour I was on finished. 😳



In spite of my photographic failures, I did manage to make a recording of this species calling along a forest stream.  The call is a musical two-part cricket like "ti-dink". 



As you would expect, it sounds very similar to its close relative the Tobago Poison Frog (Mannophryne olmanae).

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© Chris Harrison 2018

Rusty Treefrog
Boana boans

The Rusty Treefrog (Boana boans) is a widespread tropical treefrog from wet forests throughout the Amazonian basin.  I heard these frogs calling when we were in the Amazonian side of Ecuador, but I lost those recordings when my recorder was lost.  So I was very happy to get another chance to record them when we were in Trinidad in December 2018.

I heard many dozens of these Rusty Treefrogs calling from along the roads as we drove back to the Asa Wright Nature Center at night.  Unfortunately, they were calling quite a ways from the nature center and I couldn't get back down there to record them.  I finally did manage to record a single individual calling from beneath this creek bank one night near the nature center.  I was unable to find the frog for a photo though.😢  It was on the opposite bank somewhere....?



I think this frog's call as a barking "wark".  To my ear it is very reminiscent of North America's Barking Frog (Craugastor augusti).


So I was glad to get this species on my recording lifelist but, once again, I would like to be able to say I had actually seen one!  *sigh*
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© Chris Harrison 2018

Whistling Grass Frog
Leptodactylus fuscus



Leptodactylus fuscus
Waller Field, Trinidad
The Whistling Grass Frog (Leptodactylus fuscus) is found in savannas habitats from Panama down into South America east of the Andes.  They are a grassland species that calls from flooded grassy marsh areas.  I photographed and first recorded these frogs in Trinidad on an abandoned airfield at the edge of the Aripo Savanna protected area.

The call of the Whistling Grass Frog is, as you can imagine, an upward slurred whistle.  It is probably best described as a whistled "wheep".  It is quite a piercing call and travels some distance.  The frogs call from flooded grassy areas.

Here is a single individual calling from a flooded roadside ditch in Bon Accord, Tobago.  It was the only individual of this species I heard here in spite of the fact that there were large choruses of Leptodactylus validus calling all around.


Here's a large chorus calling from the Aripo Savanna area where I photographed the individual shown above. (The downward whistled "whee-oo" you hear among the frogs are Common Pauraques - a type of nightjar - calling from near the frog chorus) -


Looking at the spectrogram of the individual from Tobago, you can see the single upward slurred nature of the call and the sharp "whip" to the end of the call.


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© Chris Harrison 2019

Urich's Litter Frog
Pristimantis urichi


Urich's Litter Frog (Pristimantis urichi) is a small ground dwelling frog found only in Trinidad and Tobago.  This species was very common in the forested areas of the Northern Highlands when I was there.  Each night we heard them calling from the forest and occasionally we would find an individual hopping on the ground or climbing on low leaves.




Like other related small "tink" frogs in the genera Pristimantis and Diaspora, this species appears to call from leaves of low shrubs within the forest at night.   This is how we usually found them.  In spite of standing near hundreds of individuals over several nights, we were never able to see one calling.  Their short high pitched calls are very difficult to pinpoint to a source!




The call of this species is similar to many small Litter Frogs in the genus Pristimantis.  It is a sharp, metallic, whistled pip sound.  It carries quite well in the forest and is hard to pinpoint because it is such a short call.


The metallic pip has a carrier (dominant) frequency of about 3160Hz.
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© Chris Harrison 2018

American Toad vs. Southern Toad
Anaxyrus americanus vs. A. terrestris

When I drove to Florida recently, one of my target species to record was the Southern Toad.  I hadn't really learned the call in advance but I figured I would recognize it when I heard it since I knew most of the other species in the state.   On the way, we stopped one evening in southern Mississippi to do some herping and I heard a long trilling call.  At first I thought it was an American Toad and recorded it without thinking.  A few minutes later we found a toad on the road, but it was a Southern Toad.  That's when I realized I was too far south for American Toads...so what was that call?  I pulled up my Lang Elliott recording of US Anurans on my Ipod and listened.  It was indeed, the Southern Toad.  I had no idea they sounded like American Toads!  

Actually, there are several species of similar looking Anaxyrus species in the Southeastern US; Fowler's Toad, American Toad, and Southern Toad.

Fowler's Toad (Anaxyrus fowleri) looks similar to the American Toad (Anaxyrus americanus) but is easily separated by call.  I have dealt with those two species in a separate blog post.  Southern Toad (Anaxyrus terrestris) is easily separated from American and Fowler's Toads by the enlarged posterior extensions on its cranial crests.

Southern Toad
Florida


American Toad
Arkansas
So why a comparative post?  Because although Southern and American Toad only overlap in a small part of their ranges, as I just learned, their calls are very similar.  So how do you tell them apart?

Where they do come near each other, the American Toad is found in the mountains and Southern Toad is found in the below the fall line in the Coastal Plain.  But there are areas where both toads can be found in the same areas.  Here is an approximate range map for the two species in the Southeastern US showing the possible areas of overlap (this map is not meant to be accurate county by county, just an approximation).  Red represents the range of American Toad, yellow represents Southern Toad and the orange the possible zone of overlap.

Both species have a call that is a long high pitched trill.

Here is the American Toad (Anaxyrus americanus)


and here is the Southern Toad (Anaxyrus terrestris)

Southern Toad call


Looking at the spectra of the two calls, we see that the Southern Toad call is a noticeably higher in pitch than the American Toad.   In this example we see the American Toad with a peak frequency of around 1900 Hz while the Southern Toad is visibly (and audibly) higher with a peak of 2350 Hz.


So although these toads barely overlap in range, their calls are similar enough sounding that in the zones of overlap, it might be worth listening carefully or recording the call just to be sure.

EDIT - May 2019 - I started trying to use my understanding to identify some toad recordings on iNaturalist.org.   As I did, I wondered if my conclusions held for all American and Southern Toads, so I did a little research.

I found and listened to a few known recordings of each species and measuring the carrier (peak) frequency for each species trills.   I used some recordings from Lang Elliott's excellent Frogs and Toads of North America CD, some recordings I had, some recordings from reputable state websites and some recordings of calling toads from YouTube (where I could confirm the ID of the caller).

For American Toads, I measured nine samples that had a carrier frequency range from 1452 to 1877 Hz.   The mean value was 1658 Hz.
For Southern Toads, I measured ten samples that had a carrier frequency range from 1901 to 2284 Hz.  The mean value was 2095 Hz.
There was no overlap between the 19 calls between species.

Just to help visualize the difference, I made a quick box plot in Excel.


On the box plot, you can see the difference in range and lack of overlap.   So I feel more confident that these two similar sounding species can be differentiated by call, even if it does take a recording and a bit of analysis with Audacity (the excellent, free, open source audio editor)

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© Chris Harrison 2018 & 2019