Body coloration is important to organisms for a wide range of reasons including mate attraction, camouflage and thermoregulation. Short term changes in body coloration in frogs have been reported for a number of species and may be quite common. However, this phenomenon is widely under-reported, especially from the tropics. Here, I report color changing ability in Urich’s robber frog (P. urichi, Craugastoridae) from the islands of Trinidad and Tobago.
At 2000 h on 4 August 2012, numerous calling males were found on the north slope of Cerro del Aripo in Trinidad. Males were calling on low vegetation less than 0.5 m off the ground. All calling males were light pink in color except for the supratympanic fold which remained dark.
Five of these males were collected from the field as vouchers and placed individually in plastic bags. The following morning (approximately twelve hours later) all five individuals had dramatically changed color to a deep brown with various lighter stripes and/or blotches.
At 2400 h on 23 January 2013, another calling male was found west of Englishman’s Bay in Tobago. This male was calling approximately 1 m off the ground inside a rolled up dead Heliconia leaf. Similar to the observations from Trinidad, this male was a light beige or pink color while calling, though unlike in the Trinidad specimens, the supratympanic fold was not darkly colored.
This male was collected as a voucher and approximately nine hours later it had also changed to an overall deep brown color.
These observations suggest that Pristimantis urichi is capable of substantial color change over relatively short time periods. Other workers have reported on the highly variable coloration of this frog and the individual color plasticity reported here likely contributes to these earlier observations. Further studies on the behavioral use and mechanisms behind this color changing ability would be useful!
Note: Voucher specimens were deposited in the University of the West Indies Zoology Museum (UWIZM). I also acknowledge the Trinidad Department of Forestry and the Tobago House of Assembly, Department of Natural Resources and Environment for research and collection permits. Thanks to Adrian Hailey for help in the field and Mike G. Rutherford at UWIZM for data on specimens.
My colleagues and I have just published a paper describing a new rain forest frog in the genus Guibemantis from northern Madagascar.
We named it Guibemantis milingilingy, the latter part of which means “in an uncomfortable position” in Malagasy. This refers to the difficulty of accessing the leaf axils of the Pandanus plants in which these frogs live in Marojejy National Park. Congrats all!
My students from “Natural History of the Vertebrates” and I set up our wildlife cameras again. This time, we put them out in the forest along the College of Wooster Golf Course, right in the middle of the town of Wooster, Ohio. In addition to cottontails, possums, raccoons, etc., we got lots of deer photos
one of a squirrel bringing leaves back to repair its nest
and (surprise) more than a few shots of coyotes. These photos were almost always taken in the dead of night when these clever carnivores are unlikely to be seen. Someone (or something) is always out shopping for dinner!
Recently, I got a few wildlife cameras for my “Natural History of the Vertebrates” class. We deployed them out at Fern Valley Field Station for about a month (January and February 2018). The great thing about these devices is that you can see up close and personal some of our wonderful wildlife that you might not ever otherwise see. Below are some of my favorite pictures:
Is this a red or a gray fox? I can’t tell for sure without color.
Several other photos were taken weeks earlier – I thought these guys were supposed to be true hibernators?
Always up to something, raccoons are common residents at Fern Valley.
No surprise here – white-tailed deer out for a late night snack.
On the Caribbean island of Tobago, there is an odd snake. Many snakes are well camouflaged to blend in their environments, to surprise a tasty meal and to avoid their own predators. Other snakes are brightly colored to advertise their dangerousness to predators (called aposematic coloration). Coral snakes are an excellent example of aposematic coloration, with conspicuously banded color patterns usually in some combination of red, black and white or yellow (and the deadly venom to back it up).
There are also a host of coral snake mimics that look like coral snakes but are not venomous or only mildly so. These mimics get protection for looking like what they are not. However, the snake on Tobago (Erythrolamprus ocellatus), is neither well camouflaged nor a good mimic of coral snakes. It is red with black blotches (not rings) and virtually no white coloration at all.
Now, Tobago does not have coral snakes (though neighboring Trinidad does) and we hypothesized that E. ocellatus was in the process of evolving away from being a coral snake mimic in their absence.
In summer 2014, Erin Hodson (’15) and I did a field experiment to test this idea. Erin (and her friends and family) laboriously made 480 clay replicas of E. ocellatus and the relevant coral snakes (see below). We then hauled them down to Trinidad and Tobago to set out and see what would attack them. Notable overweight baggage fees were incurred.
The paper describing the results of our work has recently appeared in the pages of the journal Evolutionary Biology. Feel free to look it up and see what we found!
Erin E. Hodson and Richard M. Lehtinen. 2017. Diverse Evidence for the Decline of an Adaptation in a Coral Snake Mimic. Evolutionary Biology 44: 401–410.