Readers’ wildlife photos

Today we have photos of amphibians and other items from Matt Moran, an ecologist at Monteverde in Costa Rica as well as Professor Emeritus in the Department of Biology and Health Sciences at Hendrix College, Conway, Arkansas.  Matt’s captions are indented, and you can enlarge his photos by clicking on them.

These are photos from the Children’s Eternal Rainforest in Costa Rica (25,000 hectares), where I work as a field biologist. I am engaged in several projects, but my major one is a study on the status of amphibians in the park. Amphibians around the world have been declining and this area of Costa Rica is one of first places it was documented. While many theories have been developed as to why amphibians are declining, the one with the most support that explains the sometimes sudden collapse of amphibian populations (especially frogs) is the arrival of a pathogenic fungus (Batrachochytrium dendrobatidis), commonly called chytrid. This fungus infects the skin of frogs and often causes high levels of mortality. It has been implicated in the extinction of dozens of species of frogs around the world.

In the Monteverde area where I work, the population collapses occurred in the late 1980s. Initially, 25 of the known 50 species from the area were missing, but over time, most reappeared, apparently surviving in small numbers and then recolonizing larger areas. It appears that this was a major selection event, so that individuals with natural resistance to the fungus survived to reproduce, while most died. It is estimated that in many species, over 99% of individuals died. About 5 species originally found in the area appear to be totally extinct. Others still missing from here exist elsewhere, although often at critically low levels. Many, however, have recovered and probably exist at levels similar to pre-fungus invasion times.

I am attempting to determine the frog community structure 35 years post-chytrid invasion. These data will be valuable in two ways: 1) to determine how the community structure has changed over the last 35 years, and 2) to determine how future community structure is different from today so that we will have long-term population trends (using now as a baseline).

This is an amazing place to work. I retired from academia several years ago and this has become my new passion. It is one of the most biodiverse protected areas on the planet and every minute I spend in the forest is enchanting beyond description.

Emerald Glass Frog (Espadarana prosoplebon). This is the most common glass frog (Family Centrolenidae) found in this area. As their name suggests, they have transparent skin on the ventral side and their internal organs are easily visible. Interestingly, this species, like most glass frogs, does not appear to have declined because of chytrid fungus invasion. Like all glass frogs, this one breeds in streams:

Reticulated Glass Frog (Hyalinobatrachium valerioi). A fairly common species in mid-elevation areas of rainforest. It is easily identified by the large yellow spots on the dorsal side:

Clay-colored Rain Frog (Pristimantis cerasinus). A small frog found perched on leaves in the rainforest. It is identified by its eye color, often called “sunset” eyes, with the contrasting yellow (dorsal) and brown (ventral) parts of the iris. It has direct development where eggs are laid on the forest floor and the tadpole develops inside the egg directly into a miniature version of the adult. This species declined with the arrival of chytrid fungus but now appears to be relatively common again:

Sunset over the Children’s Eternal Rainforest, Costa Rica:

Evergreen toad (Incilius coniferus). A common toad found in mid- and low-elevation rainforest. This species is one of the few true toads (Family: Bufonidae) that can readily climb vegetation, although they are also often found inside the burrows of other animals. They are highly toxic and probably have few predators:

Puma (Puma concolor) track. These big cats are common in rainforests through Costa Rica. We also have jaguars (Panthera onca), but jaguar tracks are the size of your hand, including the fingers!!, while puma tracks are the size of the palm of your hand. Because it had rained very hard the night before, I knew this track was less than 8 hours old!:

Atlantic Forest Toad (Incilius melanochlorus). Another common toad. This one declined dramatically with the arrival of chytrid fungus but now appears to have fully recovered:

A giant Ceiba tree (Ceiba pentandra). This is one of largest trees in Central America, reaching heights of over 70 meters. Because they often grown above the canopy (emergent tree), they are the favorite nesting sites of many raptors (e.g., Harpy Eagle, Harpia harpyja) where the elevated platform provides a good viewing point and relative safety from nest predators. This tree may be over 300 years old:

When I first saw this snake, I thought it was the highly venomous Fer-de-lance (Terciopelo in Costa Rican Spanish, Bothrops asper). However, this is the False Fer-de-lance (Xenodon rabdocephalus), a harmless mimic. I have often wondered if it is true case of mimicry trying to make potential predators think it is the deadly pit-viper or if its patten is actually an example of convergent evolution for camouflage. It might function in both ways in that it does provide great camouflage, but if spotted, it also has the pattern of something very dangerous!?:

JAC: I added a photo of a real fer-de-lance from Wikipedia: