Monday, June 25, 2012

Field Notes from Tobago


Some readers may have noticed an absence of activity on this blog, this is due to my field schedule for the summer and the generally poor internet connections available in Charlottville, Tobago. We have been sitting in a beach house for a week doing daytime hikes, snorkeling, and hanging out with the locals with few signs of the island’s unique herpetofauna.   Day time walks along streams and nighttime trail and stream walks have produced few frogs, lizards or snakes. During the day Ameiva atrigularis is highly visible as is the ever present Anolis richardii . An occasional glimpse of an iguana, an iguana nest, or locals hunting them is also a reminder that we are in the Neotropics. But, there has been no significant rain since we arrived a week ago.
One interesting observation on A. richardii, is that there appear to be two morphs of males: one that is exceptionally large (120 mm) and often has white head markings and another that is smaller (about 70 mm) that appears to be mature with a well-developed yellow dewlap and hemipenal bulges in the tail. In early and mid-morning these lizards are sitting on vertical surfaces such as tree trunks, stream banks and road-cuts.
The snakes have been hiding. 

Gabe caught a small Ruschenberger’s treeboa on a night walk along Frenchmen’s River and while walking the Blood Bay River yesterday we found a Liophis melanotus neosus on a gravel bar in the river. It died because it had been run over by a Ford Pickup truck that was parked 20 meters away – road kill in a river. 
And, Stevland found a nice melanistic Spilotes pullatus, just short of two meters in total length. 
Mike retrieved a greater windward skink, Copeoglossum aurlae from under the bark of a tree while looking for gastropods (evidence is accumulating that this species is quite arboreal).
Frogs have been present but usually the species associated with disturbed habitats. Leptodactylus fuscus can be heard continually along roads; Hypsiboans cepitans is also present in small choruses. The North Side Road was very productive last year but this year a landslide closed the road a short distance from Charlottville. The slump backed up water in the ditch and frogs ready to exploit any body of water have been chorusing here is good numbers. Of interest is Leptodactylus validus which have laid its eggs on the flooded road with females standing guard over their tadpoles.

During stream walks the glass frogs were calling from the canopy and Mike Rutherford managed to find one at eye level. One of the Glasgow students also found a tiny (9 mm) hylid that may be a metamorph of Trachycephalus typhonius. And of course, marine toads are ever present in streams, forests, and the local bars.

The trails above the fishing village are narrow and the terrain is steep, but within a few minutes we found several calling male Pristimantis charlottvillensis and a six millimeter frog that is probably Prisimantis urichi or P. turpinourm – Leptodactylus fuscus and L. validus are here also.

So, the rains have now started and with a little luck the frog and snake activity will pick up tonight.

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