Fishing Bats, Singing Frogs, Ravenous Toads and Rare Birds

        Richard Veit and Danielle Fibikar banding an Antillean cave bat. Photo William Stelzer
Once again, Richard Veit, a professor of biology at the College of Staten Island in New York City, brought a group of college students to St. John to examine the rich habitats surrounding the Virgin Islands Environmental Resource Station (VIERS) in Lameshur Bay. The area seems to be full of familiar wildlife (including over 60 types of birds), while also supporting newcomers and at least one species thought to have disappeared.   

I met Professor Veit and two of his graduate students last April at VIERS and reported for the Tradewinds on their respective research projects: Danielle Fibikar is working on documenting the size and health of local bat populations, and Pearl Cales is studying different types of frog vocalizations, while also identifying changes over time in their density and distribution in certain areas of the island.

These researchers returned to St. John in November, and then came back again in January to follow up on their subjects, while the undergraduates in the Tropical Ecology Course were just getting familiar with the different birds, lizards, and crabs around Lameshur.    

My husband and I, and local photographer Bill Stelzer, were excited take a trip out to VIERS and catch up with the research team to get an update about their findings. We set out along the road by the beach at Lameshur, where they set up fine-threaded ‘mist’ nets to catch bats flying along the roadway after dark.
Close up of fishing bat's face. Photo William Stelzer. 

The first ones caught were fishing bats, Noctilio leporinus, out for dinner. One of the fishing bats that got tangled up in the net had a familiar face – they had caught him several times before, most recently just a few days before. It was easy to tell because they put tiny metal tags on the wings of the bats before releasing them. Their re-catch rate shows that there is a fairly stable community of fishing bats in that area. The researchers also weigh and measure the bats. The one caught a few days earlier hadn’t grown in such a short time but turned out to be 8 grams heavier than before, probably because he had just eaten a small fish that evening before flying into the net. These bats fly low over the water in the dark using echolocation to locate little fish and grabbing them with the sharp claws on their hind feet.

                                             Antillean cave bat resting in a tree. Photo William Stelzer

The other bats caught that night were fruit-eating Antillian cave bats, Brachiphylla cavernarum, which seem to be getting more numerous on St. John based on the recent mist net counts and an examination of the buildings at the old Reef Bay sugar mill. These bats represented less than 10 percent of the bats netted on St. John by the Island Resources Foundation team in their 2009 survey (with Jamaican fruit bats, Artibeus jamaicensis, making up close to 75 percent of the total). The cave bats have been listed as a species of ‘Greatest Concern’ on the Territory's Endangered Species List, probably due to a limited number of caves for roosting and a general loss of habitat.

The researchers told us that one night they caught five different types of bats within a few hours – including (besides the ones already mentioned) a relatively common insect-eating velvety free-tailed bat, Molossus molossus, and a rare red fig-eating bat, Stenoderma rufum, which is only found in Puerto Rico and the Virgin Islands, and is also listed as a species of Greatest Concern on the Virgin Island’s Endangered Species List. During the Island Resources Foundation three-year survey, there were only 15 of the red fig-eating bats caught - out of 1,200 - slightly more than one percent of the total.    
Meanwhile, Pearl Cales was chasing a Caribbean White-lipped Frog in the bushes along the road. It got away at one point and hid in a large puddle, but eventually it raised its face up to the surface of the muddy water and she was able to recapture it. She measured and examined it, then snipped off a tiny piece of its toe for a DNA sample to verify its identification (since the little frogs are difficult to distinguish with scientific certainty otherwise).

     Caribbean White-lipped frog. Photo William Stelzer

Pearl is focusing part of her research on documenting the different sounds made by the white-lipped frogs. She is also doing a survey of overall frog sounds at selected points to see if there are any changes. Mostly she is concerned about whether there has been an invasion of large cane toads, which could potentially eat up many of the local tree frogs. This year, she did find one cane toad in Coral Bay on the flat land near the site of the Roller’s farm. 

     Pearl Cales with cane toad

As a bird lover, I was pretty excited to hear that Professor Veit had also identified a rare bird in the flat area near Coral Bay – a screech owl, Otus nudipes, that has been found only in Puerto Rico and the Virgin Islands. In 1995, these birds were declared extinct in the Virgin Islands because a careful survey of the three main islands (which have the woody habitats they require) had turned up no evidence of them. I thought I had heard an owl in the night recently, and wondered if it could have been this type. Although the recorded common cries of the screech owl didn’t exactly match up with the hooting sounds I remember hearing, these little owls do apparently make loud ‘coo-coo’ sounds - as a result of which they were given the name “Cuckoo-bird” in the Virgin Islands.

Professor Veit also saw another unusual bird in the lagoon near Lameshur Bay – a Little Egret. This bird is a Eurasian species that is in the process of colonizing the western hemisphere. They first nested in Barbados in 1994, where there are now 15-25 nesting pairs. That is still the only western hemisphere breeding location, but they have been recorded on many Caribbean islands including Puerto Rico, and have even been found as far north as Newfoundland. It looks like a snowy egret, but has two distinctive thin feathers at the back of its head.

In addition, he ran into four brightly colored Adelaide’s warblers, which are generally found only in Puerto Rico, along the south shore trail near VIERS. These sightings of rare birds were particularly interesting to me, since I was asked to lead an early morning bird walk at Lameshur during the Unitarian Universalist Fellowship retreat at VIERS. Meanwhile I have been practicing trying to identify the different bird songs and frog voices around my house.   

Falling in Love with Bats

                                             Danielle Fibikar with St. John fishing bat. Photo William Stelzer 
Danielle Fibikar first came to St. John for a college course in Tropical Ecology at VIERS – the VI Environmental Resource Station in Lameshur Bay. During the day she was introduced to field research methods while studying lizards, hermit crabs and hummingbirds, but it was at night that she found her true passion – catching bats!  

One of the course leaders was Richard Veit, a professor of biology at the College of Staten Island in New York City. In the evenings, he set up finely-woven ‘mist’ nets across the road through the forest in order to trap and study the bats flying by – then tag and release them.
Danielle was hooked after she got her first close-up look at a large fishing bat with dark, silky wings (Latin name Noctilio leporinus). Back in New York she designed a plan for graduate research on bats in collaboration with Professor Veit.  

Not many people are familiar with the different types bats on St. John – especially since they are mostly active after dark. A 2006-2008 mist net survey of bats on St John conducted by the Island Resources Foundation (IRF) identified 6 different species. The most visible ones are the velvety free-tailed bats that can sometimes be seen chasing bugs at twilight around people’s houses. The most numerous by far are the Jamaican fruit bats. You can usually see some of them roosting during the day on the roofs of the buildings at the old Reef Bay sugar mill, possibly along with Antillean cave bats. 

                                         Velvety free-tailed bat (Molossus molossus). Photo Danielle Fibikar.                                 

One night when the IRF survey team was here they set up a mist net across the Fish Bay gut, and I went out to see what they caught. That night I got to touch a pregnant fruit bat. Afterwards I was inspired to read about tropical bats, so I was very excited to meet the researchers from Staten Island at VIERS, where I was attending a retreat organized by the Unitarian Universalist Fellowship.

The first night the whole UU group went out and waited along the moonlit road to see what the nets would catch. I felt a mystical thrill when, after we had been sitting in silence and anticipation for what seemed like a very long time, one of the large fishing bats suddenly swooped past us, the moonlight shining on its wings – and then flew right over the net.        

I went back to VIERS again a couple of times while the Staten Island researchers were there because I really wanted to see one of the fishing bats close up. When I finally did, I could understand why Danielle found them so attractive. Dark and strong, they remained dignified even when being captured and examined. She crooned to them lovingly while measuring them, tagging them, and taking samples of their hair (to test for mercury from the fish they eat).

                                                    Fishing bat with wing tag. Photo William Stelzer

 The research she and Professor Veit are doing on St. John ties in with their work in New York on white-nose syndrome, a fatal fungal disease threatening the survival of cave-roosting bats. It was first found in a cave near Albany, New York and has spread widely across eastern North America. The fungus is thought to be unable to tolerate temperatures above 68 degrees Fahrenheit, but if they find that the spores are carried on the hairs of migrating bats during the warmer summer months, there is a possibility that it could be transported and spread into warmer locations.

I asked my photographer friend Bill Stelzer to come along one night to VIERS. I knew he would be interested because when we were both doing volunteer work with the National Park archeologist Ken Wild, Bill once spent the night by the Reef Bay petroglyphs to see if he could see bats there. Ken’s archeological research indicated that the stone carvings by the freshwater pool were made by pre-Colombian Taino people and represented the bats drinking there – which were viewed as important links between the human and supernatural worlds.

The Staten Island researchers also went to the petroglyphs pool and found 5 red fig-eating bats there, apparently attracted by the ripe fruit from a strangler fig tree. These bats are quite rare, and endangered due to land development and habitat loss. During the three year IRF survey, only 10 were seen on St. John, out of a total of over 500 bats netted. The IRF report recommended actions in the Virgin Islands to protect remaining forest land and replant native fruit trees, and to educate people about conservation of local species. (Bats are the only native mammals in the Virgin Islands.)      

Bats serve ecologically critical roles in pollination and seed dispersal, and the mosquito eaters near houses certainly also provide a valuable service to people living there. But I don’t think their true significance can be measured in terms of bugs and seeds and pollen.  

People tend to react emotionally to bats. Some are afraid, thinking about vampires, and warnings from grandmothers about bats getting caught in their hair. Others are attracted to their wildness. They remind us of the life forces that remain mysterious and untamed, and maybe also draw our own wild spirits out of the shadows. 

                                                                       Antillean cave bat. Photo William Stelzer

Invasion of the Coqui Snatchers?


Whistling coqui on bromeliad
Photo William Stelzer.

Imagine young lovers calling out to each other in the darkening woods, looking forward to meeting up for a night of romance under the stars. Suddenly a bright light appears above them, which seems to be coming from the forehead of an enormous dark figure stalking noisily through the underbrush. As they hesitate, startled and confused, one of them is snatched up and carried off.

A short distance away the captive is poked and probed, and then something sharp snaps, taking off a couple of toes. The victim jumps and squirms and manages to escape – hopping off into the dark with an improbable tale about a frog-snatching, toe-biting monster lurking in the forest.

What sort of creature would do this?

It turns out to be a young woman wearing a miner’s light strapped to her head – Pearl Cales, one of the graduate students from the College of Staten Island in New York City doing research periodically at the Virgin Islands Environmental Resource Station (VIERS). She has been studying the frogs’ songs and calls, and also has a good eye for spotting them. She finds them hiding on low parts of trees in forested areas, inside bromeliad plants, or in the leaf litter on the ground. It takes quick hands to catch them.
                                           Pearl Cales taking DNA sample from tree frog. Photo William Stelzer.

But why is she snipping their toes? Apparently it is difficult to identify the different types of native tree frogs just by their calls. The toe samples are used for DNA analysis.

The dominant type of frog on St. John is the Whistling Coqui (Eleutherodactylus cochranae), which is found only in Puerto Rico and the Virgin Islands. These frogs are quite small (about the size of a quarter) and are brown or gray with small brown spots on their throats and legs. They mostly sleep in bromeliads during the day and eat insects at night. They also lay their eggs in the bromeliads. The eggs hatch after about two days, without turning into tadpoles, so these frogs do not need to breed near a body of water.  

The Red-Eyed Coqui (Eleutherodactylus antillensis) is a similar tree frog, also mostly found only in Puerto Rico and the Virgin Islands but not as common. In addition to its red eyes, it also has distinctive black streaks in front and back of its eyes. During the day, these frogs are generally hiding on the ground, but at night they get up on low bushes and branches to catch insects. After a rainstorm, the female will lay eggs in the wet leaf litter. These eggs too will hatch without any tadpole stage.

Unlike a coqui, the Caribbean White-lipped Frog (Leptodactylus albilabris) is semi-aquatic and needs to be close to water for breeding. The eggs are laid on the ground near a stream or a ditch suitable for tadpoles. Pearl found lots of these tadpoles in large puddles of water along the road by VIERS.

One of things Pearl is investigating is whether there are impacts on local frogs due to the introduction of three non-native species: the Puerto Rican Coqui, the Cuban Tree Frog, and the Cane Toad (Bufo marinus).

St. John is a small island and, as everyone knows, non-natives can be quite invasive, disrupting the domains and routines of the locals, and encroaching on or destroying their habitats.

Most people in St. John are already familiar with the Cuban frogs, which are much larger that the native ones. So far Pearl has not seen much impact from them on local St. John frogs, though in the British Virgin Islands coqui populations seem to be declining where Cuban frogs have spread into their customary habitats. (These big frogs can also cause lots of trouble for homeowners by squeezing into the water pipes – and even breeding in swimming pools).

                                                       Pearl Cales with Cuban Tree Frog. Photo Richard Veit

The even larger cane toads are of more concern. They have been showing up in Coral Bay, probably arriving in plants imported from Florida (like a number of other invasive species). These toads are voracious predators and will eat the native frogs, along with many other small creatures. (If threatened, they also produce a toxic secretion that can burn your skin and poison your pets.)

These introduced invaders seem to be the really dangerous coqui snatchers.


                                                     Cane toad.  Photo Wikipedia


Here are some interesting links for learning about frogs and listening to their calls:

Different coqui frog calls:

Caribbean White-lipped Frog:

Cane Toad: