Seabirds Nest on Offshore Islands to Avoid Predators

Red-billed Tropicbird at Carvel Rock

 

When tropicbirds and other seabirds are not nesting, they mostly stay out at sea, so you aren’t likely to see them unless you, too, are out on the water. And you probably need a boat to see them even when they are settled down and nesting. 

 

When I put together a book of photos of St. John birds, Looking for Birds on St. John, a few people (mostly sailors) asked why tropicbirds weren’t included. I explained that I was generally birding on land and had never seen a tropicbird. To me, tales of these high-flying white birds with long ribbon tails seemed fantastical. But then I got excited about trying to actually see one for myself.   

Red-billed Tropicbird

In 2024, as a Christmas treat, one of my sons rented a small boat (actually a Zodiak, a larger version of a dinghy) and captained our family around St. John. I had heard that some of the seabirds nest out on the back side of Congo Cay, off the north shore of St. John, so I asked to head out there first. Unfortunately the water was very rough when we got there, with swells from the north breaking against the cliffs and then quickly rushing back out to whack us from the other side. I was afraid we would capsize, and I would find myself dragged underwater by my heavy camera and telephoto lens. Anyway there was no way I could focus my camera with the boat lurching so heavily. Disappointed, I asked my son to turn around. 

 

We decided to go along the south shore of St. John instead and had a lovely day snorkeling. I looked for nests on the high cliffs by Ditliff Point and Ram Head, and deduced from telltale white poop stains that some birds had spent substantial amounts of time on those rocks. We didn’t actually see any birds there as we went by though.    

  

This past Christmas my son took us out again, and the water was somewhat calmer on the north shore. But again, it was too rough behind Congo. Then towards the end of the day, as we were returning to town along the north shore, he swung by Carvel Rock, which is just off the east end of Congo, and suddenly called out “There it is!” 

 

An unmistakable tropicbird was fluttering its long tail feathers above the top of a craggy cliff on Carvel Rock.  

Red-billed Tropicbird

 

After hovering for a while, the bird approached the rocks.   

 

Then it settled down on a rock shelf that seemed to be serving as a nest. 

 

When the tropicbird flew up again, I couldn’t see any sign of nesting materials on the ledge, or an egg or a chick. But we were looking up from the water and didn’t have a good view into the back of the cliff. 

 

I read later that a female red-billed tropicbird usually only produces one egg at a time, and just lays it directly on the rocks, cradled in a cavity or crevice. Then both parents help incubate it, for about a month and a half. Once it hatches, the chick stays in place for about three months until it is ready to fly. So if all goes well, there will still be some tropicbird activity at Carvel Rock for a while yet. Their peak period for nesting in this area is between December and March. However, a red-billed tropicbird pair might breed almost any time during the year, depending on water temperatures and availability of fish. (Cooler water generally means more fish.)

 

Meanwhile, the V.I. Audubon Society’s volunteers from Lovango Cay for the annual Christmas bird count, Dan Boyd and Fiona Russell, reported seeing two white-tailed tropicbirds while they were out scanning for seabirds from their boat. And also a red-billed one. Both types are known to nest in this area. So now I have a new mission: to see a white-tailed tropicbird too. They have lighter colored bills – more yellow or light orange – and black lines of feathers along their backs. 

 

Nesting on a remote island helps protect a bird’s eggs and chicks from being eaten by a foraging rat, cat, dog, crab or mongoose, or even another bird, like a pearly-eyed thrasher or a hawk. Plus it’s harder for people to come out and collect the eggs for food.

 

The nests are also less likely to be trampled, by people or goats. 

Goat climbing on a cliff on Lovango Cay

On the small offshore islands, rats that swim over to look for food seem to be causing the most problems. The V.I. Audubon Society has been collaborating with the Friends of the V.I. National Park, and park managers, to support a study of invasive predators on some of the cays within the park boundaries. A recent survey conducted by an Island Conservation team indicated that black rats are present on most of the small islands in the park. Implementing a plan for eradicating the rats would be an important step towards protecting the nesting seabirds.   

 

Carvel Rock already seems like a pretty secure place. Located just outside the VI National Park, it looms up in the water like a fortress.

Carvel Rock

 

There is no beach or space to land a boat, and the cliffs rise sharply from the water. Still, I have heard that people sometimes climb the cliffs to jump off. And I suppose a hungry, determined rat could swim over from Congo to explore new territory.  

Cliff edge at Carvel Rock

 

I was surprised to see that an intrepid tree had taken root in a crack in the rock face. I asked St. John’s local tree expert, Eleanor Gibney, about it and she said it was a native fig (Ficus citrifolia) that had been growing out there for over 50 years. I imagined a bird flying over there after eating a tasty fig, setting down, and then depositing a seed in its poop.    

 

I didn’t see many other signs of life on Carvel that day. There was one other bird, a brown booby, which seemed to just be taking a rest on the rock. These common seabirds are easily visible from the shoreline, or flying beside the ferries, but they make their nests away from people on offshore islands, usually gathering together in groups.   

 

Brown Booby at Carvel Rock

Last May, on a V.I. Audubon Society boat ride, I did see a few bridled terns nesting high up on Carvel Rock. Like tropicbirds, these are seabirds that rarely come close to shore. 

Bridled Terns nesting at Carvel Rock in May 2025

The idea of hiding out on an isolated island fortress can seem fairly appealing these days. Yet even though nesting birds are able to engage in some protective behaviors, they clearly have only limited defenses against predator invasions, climate change, more violent storms and habitat loss. Just like us. Except that hopefully we have a bit more capacity to anticipate, and avert, foreseeable dangers. 

 

Partying with Flamingos

Like people, flamingos enjoy getting together in groups and socializing. And this year we have been blessed with amazing gatherings in some of St. John’s ponds – the annual December bird count included over 100 flamingos. Wow!

 

A couple of years ago we were delighted to report just one flamingo that showed up on the south shore, so these flashy birds are providing a dramatic new bird watching attraction on St. John.   

 

Historically, flamingos were native residents of the Virgin Islands, but then early European settlers found them to be good eating – ‘tastes like a goose’. Their honking voices do make them sound a lot like geese. But of course they are so much more beautiful. Anyway, between hunting, feather gathering and habitat loss, they were all wiped out by the mid-1900s. 

 

Then in 1992 a conservation group reintroduced a small group of flamingos from Bermuda to the British Virgin Islands. Those birds successfully reproduced, and there are now hundreds of flamingos on Anegada, the farthest north island in the BVIs. Another group was later brought to Necker Island. With growing populations in the BVIs, it seems that some of the flamingos have now decided to spread out and are flying over to check out the living conditions on St. John.

 

I have been lucky enough to spend time with some flamingos having rather noisy parties. I wasn’t actually invited, but they were gracious enough to allow me to sit quietly on the sidelines with my camera. 

 

Sometimes the flamingos seem to be enjoying quiet conversations. 

 

 

Later there might be dancing.

Underneath the wings, the flamingo feathers are black, not pink.

 

And sometimes it looks like they are kissing.

 

Perhaps an embrace. Or a power move?

 

Then, all of a sudden, one of them might take offense and deliver a quick bite.  

 

Which might lead to some chasing.

Many of the flamingos in St. John now seem to be adults, judging from their size and coloring. But I noticed a few small, white ones that looked quite young. I am wondering if they might have been born on St. John over the summer, but can’t be sure. A baby flamingo grows almost to full size within a few months, and can fly soon after that, so possibly the young ones flew over to St. John with their parents. 

 

It can take a couple of years for the young flamingos to get their distinctive pink look. As they grow up they have to consume lots of red-orange carotenoid pigments (like the ones that color carrots and tomatoes). The flamingos get those pigments by eating microscopic algae in the water, and crustaceans like brine shrimp that also eat the algae. The pigments are broken down in their digestive systems and then get deposited in their feathers and skin. 

 

Members of a group of flamingos can vary quite a bit in coloring depending on their age and diet. Male flamingos are usually a bit larger and heavier, but not necessarily a darker color than females.

 

The feeding process involves the flamingos holding their heads underwater, shuffling their feet to stir up the mud on the bottom, sucking in mouthfuls of water, using their tongues to push out the water and strain it through comb-like filtering structures inside their beaks, and then swallowing anything edible. 

 

Besides algae and brine shrimp, they also pick up other small crustaceans and invertebrates, insect larvae, and some seeds and other plant material. They are able to tolerate feeding in very salty ponds where other birds don’t go because they have special glands that they can use to excrete salt through their nostrils. 

 

And when the partying is over, it’s time to rest and give thanks for the blessing of a day with flamingos.