Look Out for Land Crabs

Many people don’t ever see the land crabs in the Virgin Islands because these crustaceans live in the mangrove wetlands and mostly come out at night. The large blue kind (Cardisoma guanhumi) look a bit ghostly, and can grow to about 5 or 6 inches across their backs. They have one large claw and one smaller, thinner one. And their eyes stand up on stalks. 

 

The females are not so blue - more of a light gray. And the juveniles can be brown, orange or purplish. 

 

 

Although these crabs live on land as adults, they generally stay close to the water. They dig big holes in the mud to hide in, several feet deep, with enough water at the bottom to keep their gills damp. 

                            

 

After breeding on a full moon during the rainy season, the females deposit their eggs a couple of weeks later into shallow salt water nearby. As they grow up, the young ones may be carried by currents to other shorelines.

Our house is close to the land crabs’ territory, and they sometimes climb up the hill to visit. I occasionally wake up to hear them rattling around on the front deck, which I don’t really understand. They mostly eat leaves and vegetation, plus maybe some insects and dead things. There might be some of those things near our house, but a lot less than down by the mangroves. I think they might just be curious. 

                             

 

I was frightened of them at first. Especially when I saw them waving their big claws around. 

 

                              

 

They could possibly give you a sharp nip, though it seems that the small claw is the sharper one.

I learned that they are able to cut through tough stuff when my older son decided to catch one and tie it up with fishing line. 

 

We had sometimes seen people hunting for the crabs at night with flashlights and putting them in buckets. We were told they were good to eat, especially with rice, or in a local soup called callaloo (or kallaloo). But first you have to feed them corn for a couple of weeks to clean out their digestive systems – because of those dead things they might eat. 

 

So my son was going to keep the crab in a bucket and feed it clean food, but didn’t have a cage so he tied a piece of the fishing line to the crab’s leg and then to the bucket handle. The next day he was disappointed to see that the line was cut through and the crab was gone. 

 

The Yellow-crowned Night Herons also like to eat crabs, and aren’t so particular about how clean their food is. The night herons have thick bills that they use to punch right through the crabs’ shells. 

 

                           

 

I sometimes see crab pieces lying around below the house, and shells with sharp bill-sized holes cut in the back. 

                          

 

Once I even saw the visiting Scarlet Ibis walking around with a crab leg in its mouth. Its long bill is meant for digging in the mud, not poking holes in shells, but apparently it was strong enough to tear off a crab claw. I’m not sure about how the bird gets the meat out, though. Maybe it has to swallow the whole piece and then dissolve the shell with its digestive juices.     

 

                          

 

It’s a complex struggle for survival in the mangroves, and I sometimes feel a bit sorry for the crabs. Their shells look pretty tough, but they are actually quite fragile. As are their wetland habitats, due to the effects of climate change and human encroachment. But meanwhile I am happy that the birds I love have a good supply of food, which makes them want to stay around the neighborhood. 

 

What Makes Hummingbirds Sparkle – And Why?

 

In the bright morning sunlight, local Green-throated Carib hummingbirds can seem like precious winged jewels. They look lovely to me, but I wonder what’s in it for them. I don’t imagine they are posing in the sun just for my benefit, even though I do sometimes feed them sugar water. 

 

I read that the feathers on their throats are called its ‘gorgets’, which was the word used in olden times for the neck protectors worn by knights in shining armor. Does a sparkling gorget actually protect the hummingbird in some way, or is there some other evolutionary advantage they get?  

 

 

Up close you can see that the feathers on the front of the hummingbird’s neck are circular, and overlapping like scales. Structures within the feathers reflect and scatter the light so that when the bird moves its feathers look quite differently in a variety of light and postures. Is it trying to get attention from a prospective mate, or scare off intruders? Or just enjoying the sunshine?

 

In shadier situations, these hummingbirds still have their green throats with blue edging, but appear duller. And most of the time I just experience them as tiny dark shapes darting around among the flowers. 

 

 

 

I decided I needed to find out more about how feathers get their colors in the first place, and then how they sometimes appear so shiny. 

 

Most of the colors we see are based on pigments – molecules within cells that absorb or reflect back various wavelengths of light. I learned that bird feathers, like our hair and skin, are made of keratin, and have cells that produce melanin pigments at the molecular level in ‘melanosomes’. Melanin generally shows up as color granules in the birds’ feathers, and enables the feathers to absorb all the wavelengths of visible light. That doesn’t allow for much reflection, and mostly creates dark colors. 

 

In some birds, though, the melanin crystals are combined with tiny air pockets within the feathers. The result is that light is scattered as it hits the bird and creates a form of ‘structural coloration’ that causes us to see those feathers as green and blue.  

 

   

 

I also learned that red, orange and yellow colors don’t come from the birds’ melanosomes but from carotenoids, which are plant pigments that reflect light from the red/yellow section of the spectrum. 

 

However, birds can’t internally produce the carotenoid compounds that create these brighter colors. To get red and yellow feathers, some birds are able to consume carotenoids in their food and then store the pigments in their feathers. They could be eating plant material containing carotenoids, or eating animals that have already consumed plant carotenoids. For example, the flamingoes and scarlet ibises get some of their bright coloring from eating shrimp, which may in turn have been feeding on carotenoid-carrying algae. 

 

 

 

A Scarlet Ibis is certainly bright due to its carotenoids, and its feathers do seem to have different shades depending on the light, but it is does not flash sparkling color like the hummingbird. 

 

Hummingbird feathers have a special form of structural coloration. They are able to shine so brightly because their pigment-containing melanosomes have an unusual pancake shape, and also contain lots of tiny air bubbles. The bubbles are stacked in layers that create many different surfaces for light to bounce off. Taken all together, these adaptations produce shimmering iridescence, when the angle of the light is right.

 

 

 

 

Why would hummingbirds go to so much trouble to develop iridescent feathers?

 

Theories about hummingbird iridescence often focus on its role in attracting potential mates. Interestingly, birds have four color cones in their eyes, while we only have three, so they can see a broader range of colors, including ultraviolet parts of the spectrum. That affects how they perceive flowers, which often have ultraviolet coloring we can’t see, and also probably affects how attractive they look to each other. 

 

It could also be a protective adaptation. A bright flash of the hummingbird’s gorget could momentarily distract a predator. Or its iridescence might also serve as a form of camouflage, as the bird seems to appear and disappear by moving in and out of the light, causing confusion about its actual position.  

 

I don’t like to think that the shiny hummingbirds I see in the yard actually view me as an intruder and are giving me a signal to get lost, rather than just showing me how pretty they are.

 

Yet the truth is that they are quite complicated beings, and we really don’t know much about how they actually perceive us.  

 

Whirlwind Romance in the Wetlands

A couple of Seaside Dragonlets whizzed over a wetlands pond.

When I saw the two dragonflies together, I assumed they must be lovers. But if so, it was a strange embrace, as they seemed to be attached tail to head. 

And they were different colors – the one in front was blue and the back one was orange. 

Were they two different types of dragonflies having a battle over territory? 

 I was sitting by the black mangrove pond near my house with my telephoto lens, waiting to see what birds might appear, so I was in no hurry and was able to watch – and document – the interesting dance of the dragonflies. 

Later when I looked up the different types of dragonflies found in the Virgin Islands, I learned that these were a couple of Seaside Dragonlets, about an inch and a half long. The male is the blue one, and the female is orange. But what were they up to? 

Another time I had seen what I thought were dragonflies mating, and they were locked in a dramatic ‘wheel’ embrace. I was thrilled to get a photo of their amazing posture! 

A pair of Argia concinna damselflies (male above) hooking up on a grass stem

Those actually turned out to be damselflies, but they are closely related to dragonflies, and I read that the wheel position is the norm for mating dragonflies as well. The male’s sperm is released from the center of his abdomen, so the female (below in the photo) has to reach her tail end up and around above her to connect with the male’s abdomen and complete the ‘mating wheel’, while he keeps a tight grip on the back of her neck. 

The damselflies were perched on a sturdy piece of grass. The Seaside Dragonlets, however, are apparently more acrobatic and can do the wheel position thing even while they are flying around. 

When the male dragonfly spots an attractive female, he will fly up behind her and grab her with his legs. Then he scooches up and uses two special grippers at the end of his tail to clasp her tightly by the neck, in what is called ‘tandem linkage’. After that, they figure out how to maneuver themselves into the wheel position. 

These Seaside Dragonlets demonstrate ‘tandem linkage’, with the blue male in front gripping the female behind him with special clasps on his tail

The dragonlet couple I saw must have already finished mating. But they were still attached as they flew by. And it wasn’t just a loving embrace. I read that the male will keep his tight hold on her neck until she deposits her fertilized eggs in the pond. That way he can make sure that she doesn’t go around mating with other competitors in the meantime, as she might otherwise be tempted to do. 

A female dragonlet dips her tail down to deposit eggs in a shallow pond. 

While the dragonlets were hovering over a shallow edge of the pond, the female lowered her tail down into the water, and appeared to be releasing her eggs. They flew back and forth, and repeated this process several times in the same spot before finally taking off and disappearing. 

The male dragonlet (blue) keeps a tight grip on the female’s neck as she deposits her eggs.

When the eggs hatch, the tiny larvae, called nymphs, will swim around hunting for even smaller pond creatures to eat. As they grow, the nymphs will molt many times before finally crawling out of the pond, developing wings, and becoming adult dragonflies. 

Most dragonflies breed in fresh water, but the Seaside Dragonlets are uniquely able to tolerate the salty water in the Virgin Islands’ brackish mangrove wetlands, as well as more northern salt marshes. The nymphs are able to regulate their internal osmotic pressure to avoid damage from high salt concentrations. 

I hadn’t paid too much attention to the dragonflies by the pond before, so I was glad to be able to get some photos of these dragonlets and learn a bit more about them.

Are Sugar Feeders Healthy for Bananaquits?

Bananaquits are called 'Sugar Birds' in the Virgin Islands

 

Many people like to attract the local bananaquits by putting out sugar or sugar water. But some people ask if that is actually good for the birds. 

 

I have been one of those questioners. It is certainly fun to have an eager bunch of birds waiting for you to get up in the morning and fill the feeder. Still, for a long time I resisted getting a feeder because I thought the bananaquits were better off finding their own food in a normal bird way – like catching insects in the trees or poking their curved bills into ripe fruits and berries, or getting nectar from flowers (and in the meantime helping with pollination). 

 

Besides not wanting to interfere with the broader ecology, I also didn’t want the birds to become fat and lazy, or dependent on humans. Or sick.

 

I did sometimes put out a bowl of water for them during dry times, but wasn’t sure that was really good for them either. Some birds drank the water while others got into the bowl to take a bath. I was afraid those dirty feet in the drinking water might spread diseases.  

 

 

Then the 2017 storms stripped the islands of vegetation, and the bananaquits and many other plant-dependent birds were desperate for food. A number of people made great efforts to put out sugar for the bananaquits, and that probably helped many of them survive that terrible time. 

 

After the storms, I started to feed the bananaquits too. But I still worried about it. 

 

At first, I put out sugar water in a bowl, and had the same issue with certain birds using it for baths, even though their feathers must have gotten a little sticky. Sometimes they even knocked over the bowl in their exuberance. 

 

Then I got one of the popular painted coconut husk feeders made by Ital Delroy Anthony on St. John. I decided putting sugar water directly inside the coconut would make things moldy, so for maximum cleanliness I used a plastic cup sitting inside the coconut. That way I could wash it every morning before refilling it.

 

                        

 

Then one of my birder friends suggested that I should just give them white sugar directly from the bag. That seemed less messy. Also a more satisfying user experience for the birds – the crystals are easy to grab and take away, and more birds can get served quickly. Of course there is still quarreling and jockeying for position, but overall there is less spillage, and no one takes a bath in the cup.

 

Before long, I started worrying about whether the bananaquits, like people, could get diabetes and other ailments from eating too much white sugar. 

 

After some research I learned that wild birds are generally not susceptible to diabetes in the same way that we are, in part because they have much higher normal blood glucose levels. But I didn’t see any studies that said eating white sugar was actually good for them.  

 

Their natural diets include insects for protein, as well as fruits, berries and nectar – which contain vitamins and other nutrients. Of course, if there aren’t enough fruits and flowers around, white sugar seems better than not eating.   

                          

 

I also began thinking about why bananaquits would even eat the sugar crystals, since many birds won’t. 

 

One thing I learned is that, unlike many birds, bananaquits are able to digest sucrose, which is naturally found in sugar cane, sugar beets and many plant nectars. White sugar is pure refined sucrose. It can be difficult to digest because sucrose is composed of two simple sugars, glucose and fructose, chemically bonded together. Nectar-eating birds without the enzyme needed to break that chemical bond have to depend on plants and flowers that produce glucose or fructose. 

 

Locally, Antillean bullfinches are able to digest straight sucrose too. In fact, a male Antillean bullfinch is often the first one at the sugar feeder in the morning.  

 

                      

 

Hummingbirds can also digest sucrose/white sugar, but for them it needs to be diluted in water – about 4 parts water to one part sugar – to resemble the nectar they drink. (Many sources warn not to use honey, raw sugar, brown sugar or artificial sweeteners in hummingbird feeders, as these may cause digestive problems, contain residues and impurities, or lack nutrients.)

 

                      

 

Interestingly, the bananaquits will also drink from the hummingbird feeder when their feeder is empty, sticking their tongues into the little holes to get the sugar water. Their tongues are not as long as hummingbird tongues, but apparently long enough to reach the sugar water. Much to the annoyance of the hummingbirds.  

 

                       

I love to watch the birds enjoying their feeders at breakfast time. I am careful to keep the feeders clean, and limit the amount of sugar I put out so they can still spend most of the day foraging for themselves.

 

I do hope that the feeders benefit the birds as well, especially during the times when flowers and fruits are scarce. Still, I would like to know more about how these interactions I enjoy so much actually affect the lives and long-term health of the birds. 

A Lonely St. John Scarlet Ibis Seeks Companionship

                              

 

What a joy it has been for us to have a big red bird lighting up the mangrove wetlands around Fish Bay. Unfortunately, though, it seems like a pretty lonely life. 

 

We don’t know for sure if this Scarlet Ibis came from the flock introduced by Richard Branson to Necker Island in the British Virgin Islands, or from some more distant natural colony. 

 

Actually we aren’t even sure if it is the same scarlet ibis that first arrived in Fish Bay in 2020. It doesn’t look the same - the feathers now are much redder and brighter. However, that could be because it was an adolescent adventurer when it came, and now it is fully mature. 

 

I have been wondering if the ibis will stay around this summer, or head off somewhere to look for a mate. 

 

In the spring the ibis seemed to be spending an awful lot of time with an elegant Snowy Egret. They were often spotted walking together through the wetlands, suspiciously close together.

There was even gossip in the neighborhood about the possibility of pink babies.  

 

A Snowy Egret walking with the Scarlet Ibis in Fish Bay

 

But the snowy egret really is a ‘snowbird’ and later in the spring was ready to move on, heading north to mate with one of its own kind. Still, it seemed like those two were having a hard time saying goodbye. 

 

                               

 

Since the snowy egret left, the ibis seems to have been looking for new friends among the resident birds in the wetlands. 

 

But the other birds that live or forage in the wetlands don’t seem very interested in bonding with the ibis. 

 

The Green Herons that live in the pond get very agitated and sound an alarm whenever an intruder shows up. They seem especially annoyed when the scarlet ibis is there, maybe because it is not one of the regular island birds. Sometimes a green heron will scream at the ibis until it flies off.

 

A Green Heron with the Scarlet Ibis 

                                

The Great Egrets that come to forage in the wetlands seem curious about the ibis. However they aren’t really all that friendly, even with each other. They will often threaten other egrets that seem to be getting too close. Egrets catch fish in the pond and the ibis mostly sticks its long bill down into the mud to locate crabs and other crustaceans, so they aren’t directly in competition. Still, the great egrets like to dominate the space when they are there. (They don’t pay any attention to the complaints of the green herons.)   

 

 

Great Egret and Scarlet Ibis 

                          

 

The Little Blue Herons tend to stay out of the way of the egrets, and are generally pretty skittish about other birds they view as possible threats. Rather than menacing, they usually just fly off squawking. So I was surprised to see one of the little blue herons allowing the ibis to get very close. It was only for a few moments though.  

 

Scarlet Ibis and Little Blue Heron

                             

 

The Black-necked Stilts are more sociable than the egrets, but tend to stick together in their group and don’t really want a bigger bird hanging around when they are fishing. 

 

Scarlet Ibis and Black-necked Stilt 

                              

 

 The small, migratory Lesser Yellowlegs also didn’t appreciate the ibis following them around. And now, like the snowy egrets, they have gone north to their breeding grounds

 

Scarlet Ibis and Lesser Yellowlegs

                        

 

So what’s a lonely scarlet ibis to do? 

 

Its long curvy bill now looks black, not pink (and not just because it’s muddy work poking around for crabs). The darkening of the bill happens when the adults are ready to breed.  

 

It would be great for the ibis to find a mate, but sad for us if that means it has to leave St. John.  Unless by some chance the couple could come back and start a family here.  

 

 

Soursops, Sugar Apples and Rat Apples

         

      Friends of the VI National Park staff gave away plants and tree seedlings to community members. .  

On April 20, the Friends of the Virgin Islands National Park on St. John attracted an enthusiastic crowd for their Earth Day related plant and tree giveaway. The first giveaway was held in 2020, and the event was initiated to help local families replace some of their trees that were blown away by the 2017 storms. 

 

The fruit-bearing trees are by far the most popular. Many people love to grow their own food, even though island conditions can be quite challenging. For the last few years I have saved my Sugar Apple and Soursop seeds to sprout, and have raised seedlings to share with my neighbors, at this event and at the Unitarian Universalist Fellowship’s annual plant celebration ceremony. 

   Soursop trees were popular at the Friends of the VI National Park event. 

 

I have recently been considering some ideas, including from Indigenous writer and botanist Robin Wall Kimmerer, about feeling kinship with trees rather than viewing them as commodities – and how that perspective would benefit us, as well as the survival of all forms of life on the planet. 

 

Kimmerer points out that in some Indigenous languages the word for plants means ‘the ones who take care of us’. They are, after all, the ultimate source of almost all our food, and the only ones capable of photosynthesis.    

 

It is an intriguing perspective, but I am not sure we are ready to treat trees as other beings with their own sorts of intelligence, rather than as objects for our use or disposal. It is difficult to give up the feeling that we are entitled to dominion over nature, and to recognize plants and trees as fellow creatures with their own wisdom, experience, and entitlements. 

 

Still, kinship is not always based on genetic ties, though we do share many genes with plants. We may have parental feelings as we raise trees from seeds, proud when they grow up to be beautiful and successful. Or we may be neighbors, sharing our common joy in good weather and spring rains, or distress at being battered by autumn hurricanes. 

 

Or we might have a complex transactional relationship, like I have with the Sugar Apple tree in my yard: “I take care of you, and you give me some of your fruit, and after I have eaten it, I plant your seeds, and pass seedlings along to my friends and neighbors, spreading your genes and offspring all over the island.”

 

 

 

      A Sugar Apple in our yard provides sweet treats, and I share the seeds.

We mostly value trees for the products and services they provide. Because Sugar Apples and Soursop trees have tasty fruit, I want to grow more of them. Yet from one perspective it might seem like they are manipulating me based on my fondness for sweets. I have been serving them as a seed disperser and propagator, like the birds do. We definitely have a reciprocal relationship of sorts.

 

Meanwhile the Rat Apple trees by my house don’t offer fruit that appeals to me and don’t seem to want anything from me except to be left alone. They were on the property before I came and mostly have no trouble taking care of themselves and their seedlings. 

         A Rat Apple with flowers, buds and woody fruit.

 What value do these trees have? Maybe negative value if fruits rats come too close to the house. But now that I have learned to recognize the Rat Apple trees, I have actually come to respect them, to some extent, as welcome companions on the land. Learning the names of the trees, even if the local name is not very flattering, definitely creates a form of recognition.  

 

The Friends of the VI National Park group has established a plant nursery across the road from Cinnamon Bay where they have been raising native trees, as well as some of the popular fruit trees that were just given away. 

           Sugar Apple seedlings at the FONP nursery 

 

Some of the native trees are being planted along the National Park shorelines to replace vegetation lost in the storms and help prevent further erosion. Other seedlings are being raised to preserve species that have been on the island for many generations and now need some help with propagation and survival – before their names and contributions are forgotten. 

 

Perhaps in the future those trees will be able to provide needed assistance to us and our descendants. If we have good relationships with them.