Tuesday, April 24, 2012

Young Researchers Explore Costa Rican Rainforest - Part II: From Frogs to Birds

This is the second half of a report on the recent research trip to the Costa Rican rain forest by students from three Litchfield high schools, supervised by staff from these schools and Connecticut Audubon Society. You can find part I of this report here

Two remaining student research teams focus on different groups of vertebrate animals: amphibians, reptiles and birds. The primary focus of the amphibian and reptile team is monitoring local amphibian populations that had declined dramatically in the late 1980s as the result of an outbreak of a deadly fungal pathogen. Previous years' teams had focused on investigating the spread of the fungus throughout the relatively undisturbed rainforest habitat of the two preserves we work in: Selvatica and Rara Avis. It has become clear that the fungus persists in the habitat and is found in local tadpoles, but the encouraging news is that several species of amphibians that were absent from the preserves for more than 10 years in some cases are slowly starting to show signs of recovery.          

Local streams still host the deadly amphibian pathogen Batrachochytrium dendrobatidis, a fungus that has killed off many amphibian populations worldwide.
The students on this team spend a lot of time surveying suitable habitat and trying to locate the salamanders, frogs, lizard, turtles and snakes that are hidden in the green maze of a rainforest habitat.

Fast-moving streams become difficult to cross during rain storms
Giant aroid plants called 'elephant ears' (Xanthosoma sp.) lend some marshes a fairytale-like atmosphere
Only when you see some students wading through the marsh does their size become apparent
Hundreds of amphibians and reptiles were observed during the two week stay, representing 60 different species.


 Representatives of each species were captured and brought back to our base camp to collect valuable data and to obtain measurements on these poorly known animals
After only a few days in the rainforest students become very skilled at properly handling the animals they work with 
The reptile and amphibian team hard at work measuring the snout-vent length of a harmless Green Keelback (Chironius exoletus), a fast-moving racer-like snake.    

Data sheets are filled out for each observation and captured animal
 Below is a sample of some of the 60 species observed during the trip: 

Strawberry Poison-dart Frogs (Oophaga pumilio) are common in the lowland sections of the preserve
The Ghost Glass Frog (Sachatamia ilex) is one of the target species of the project. Once exceedingly rare in the preserve, it is now reliably found in many streams and its population is recovering rapidly.
Red-eyed Leaf Frogs (Agalychnis callidryas) require standing water to breed in. Because of the heavy rainfall this year we observed several individuals at night near large rain pools.
This rare Crowned Tree Frog (Anotheca spinosa) was first found in Rara Avis four years ago, in spite of intensive searches in the 15 years leading up to it. The discovery of four individuals on this trip could indicate a recent population increase - a very encouraging find!     

During last year's trip we discovered a species of salamander that turned out to be a new species to science  (read all about that here). Unfortunately, since we could not obtain the required permits in time, the animal was released back into the rainforest and could not be taken to a natural history museum to be described as a new species. This year we made arrangements with the Costa Rican government beforehand and of course tried hard to find another individual of this new species. We did not find one, but did end up with a related but already known species instead. Even though it was not a new species to science, it did end up being one that had not been confirmed in the preserve yet so it was still a very exciting find. This little Worm Salamander (named after its worm-like appearance - it has only miniscule limbs) turned out to be the 128th species of amphibian and reptile occurring in the SelvaTica and Rara Avis preserves, a combined area of less than 5 square miles. Quite amazing when compared with for example Connecticut, which measures over 5,500 square miles and harbors 22 amphibian and 24 reptile species.
This Worm Salamander (Oedipina pseudouniformis) is a new addition to the local herpetofauna!  
Ridge-headed Salamander (Bolitoglossa colonnea) an arboreal lungless salamander
Juvenile Turnip-tail gecko (Thecadactylus rapicauda)
Young Brown Vine Snake (Oxybelis aeneus) blending in nicely with its environment.
The defensive posture of this Bronze-backed Parrot Snake (Leptophis nebulosus) is quite impressive!
Other snakes, like this harmless Shovel-toothed Snake (Scaphiodontophis annulatus) may benefit from their resemblance to venomous coral snakes living in the same area. 
The venomous Hognosed Pitviper (Porthidium nasutum) is nearly invisible when it coils up in the leaf litter on the forest floor. 
Its arboreal counterpart, the Eyelash Pitviper (Bothriechis schlegelii) is equally well camouflaged on the moss-covered vegetation in Rara Avis
 As you can tell from the image below, the lush tropical habitat in the study area is quite suitable to hide many more biological surprises!

Of course, the main driving force behind the prolific growth of the vegetation here is sunlight, warmth and LOTS of rain. Although of obvious benefit to the habitat, the latter factor can also make research quite challenging at times. This year's bird team struggled with the prevailing weather pattern for quite a while since their main tool, mist net arrays, can not be kept open during rainy spells. As a result it made it tough for them to catch the migratory birds they were hoping for. Additional projects, such as a study of feeding preferences for local hummingbirds, were also hindered by the weather.    

Experimental set-up with hummingbird feeders sitting idle during yet another tropical down pour
Nevertheless, whenever the weather broke for a little while all the birds would start moving around to forage right away again. All in all, the bird team managed to catch an impressive variety of birds and they even banded several Neotropical migrants that winter in Costa Rica.

Keel-billed Toucan (Rhamphostos sulfuratus) in a Cecropia tree taking advantage of a break in the rain...
Frank Gallo and his bird team head out to open their nets again 
Orange Parrot-beak Flowers (Centropogon sp.) stand out against the green background of the rainforest. This is a good area to find the rare White-tipped Sicklebill (Eutoxeres aquila), a large hummingbird that lives in close association with these flowers. 

White-tipped Sicklebill (Eutoxeres aquila) feeding on Centropogon nectar
Note the strongly decurved bill that is especially adapted t reach deep into tubular flowers 
A spectacular Broad-billed Motmot (Electron platyrhynchum)
Silver-throated Tanager (Tangara icterocephala)
Scale-crested Pygmy-tyrant (Lophotriccus pileatus) a small flycatcher

One of the Neotropical migrants caught and banded by the team: a Wilson's Warbler (Wilsonia pusilla)
CAS master bander and Director of the Coastal Center, Frank Gallo, taught his team many things about birds, bird banding and the importance of conserving habitat along the entire migration corridor. Some of the birds banded in Costa Rica in March may actually show up on our doorstep just about now... Let's hope that our banded birds will get recaptured somewhere along their route so that we can learn more about their biology and improve conservation measures that can benefit these species. One of the birds captured this year was one banded by a previous year's team, indicating that it spends its entire winter in the preserve...

Frank demonstrating the vice-grip like bite of a female Black-throated Trogon (Trogon rufus)
All captured birds are weighed, measured and released on the spot 
A matching pair of White-ruffed Manakins (Corapipo altera). This locally common species is the subject of a PhD project by a local researcher. The bird team members helped this study by recording specific data and color banding these Manakins.  
The 2012 Rainforest Project team returned home with a large amount of data that will require much more time still to process and analyze. This year marked the 20th anniversary of the project and this year's dissertation day will be a special one with many alumni returning to see how the project has grown over the years. If you would like to be part of this public event, please join us on Friday April 27 at 9AM at the Forman School, 12 Norfolk Road, Litchfield.  

The 2012 Rainforest Project students and staff

Twan Leenders
Conservation Biologist

All photos © Twan Leenders and not to be reproduced without explicit permission

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