Papagaios, Life & Times on a Speculative Archipelago - The Grande Ponte Reef (Part One): Shorebirds

Text taken from a pamphlet ‘Shorebirds of the Grande Ponte Reef’, distributed by the Sociedade Ornitológica dos Papagaios (Ornithological Society of the Papagaios), 1869.

*Translated from Portuguese.

Situated between the Papagaian islands of Milagres and Vulcão and extending for more than 60 miles is the Grande Ponte reef, an undersea ridge of rock connecting Cabo Gaivota on Milagres to the northern tip of Vulcão. That the ridge runs in the same northwest-southeast direction as the latter island, combined with the reef’s proximity to the coast of both islands, has led some scholars to believe that the reef was once a land bridge between the two landmasses or at the least, a chain of smaller islands bridged the gap before long ago disappearing beneath the waves.

While dormant since 1797, the ridge is volcanic in nature, and the main routes across have changed since the islands were first settled. For the past hundred years, wisdom has been to sail around the south of Vulcão to avoid damage to ships. This has in turn no doubt benefited the reef and its animal inhabitants.

Gaze out across the Grande Ponte reef from the shore is to witness constant movement; waves lap against the beach and break on rocks protruding from or just beneath the surface of the water; fish leap from the ocean to escape predators who leap after them and continue the pursuit overland; birds flitting this way and that, flying at great speeds over the surface of the ocean or diving into the depths…

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…As with all birds on the islands, the shorebirds of Papagaios are classified into two distinct lineages: marquinhets, a tribe of the auk family, and the slenderbills (tribe Gracilirostruminae) members of the kingray family endemic to the islands. For the purposes of this text, we shall visit each group separately as marquinhets tend to venture further out on the reef while slenderbills are almost exclusively restricted to the shore.

Slenderbills

In contrast to the rocky beaches of its north coast, the south coast of Milagres – the side facing the Ponte Grande reef, are comprised of black volcanic sands. The beaches to the west of Cabo Gaivota run uninterrupted for miles and as flightless marquinhets prefer to nest on rocky shores, the sandier beaches are a good site to visit to observe several slenderbill species.

The most common slenderbill, or at least the most noticeable, the blacksands prober is around a foot tall with at least half of that being its legs. This charismatic bird struts over the sand with a dancing gait – two steps forward, one to the side, pause, one step back, pause, three steps forwards – believed to be a way of masking its presence to invertebrates living just beneath the surface who would no doubt burrow deeper if they heard the one-two one-two footsteps of a predator.

The blacksands prober has a compact body with a dark brown back and a golden throat and belly. Further to this, it has a black V-shaped marking on its chest and black stripe over its eye. In males, the top of the head and beak tuft are white with a red patch on the forehead. Females have duller head colouration, though it may still be a paler shade than their bodies. Three to five longer, dark blue tail feathers aid communication between mates which may be difficult to hear over the roar of the sea. The bird’s beak is long and pink in colour and it uses it to probe into the sand in search of invertebrates.

Another distinctive inhabitant of the black sand beaches is the moustachioed slenderbill, so named for the twirl of white feathers at the base of its beak that resemble a fashionable gentleman’s facial hair. The rest of the bird is an ashen grey, dappled with lighter tones that serve to camouflage is among the surf-sprayed rock pools, exposed at the very edge of beach at low tide. Possessing a shorter yet thicker bill than its relatives, the moustachioed slenderbill snaps up small crustaceans, molluscs and other rockpool life before retreating up the beach with the tide and waiting for its next feast.

The blacksands beaches, being far sandier than others in the archipelago, are likewise home to far fewer egg-eating specialists like the coast creeper or the beach octopus, both species favouring rockier environments to hide in on the way to raid nests. This does not mean slenderbill nests are safe however. While one parent feeds the other broods, though a keen-eyed observer will notice the birds move around the beach, roosting in spots dozens of yards apart. This fake nesting behaviour is intended to discourage predators (in this case opportunist omnivorous reptiles, digging crabs, or other shore birds) from finding the true nest, which more often than not is in the dunes at the top of the beach.

Marquinhets

…In addition to the flightless species detailed above, there are a scant few species of marquinhet that have retained the ability to fly. These species nest in the high cliffs of the island and feed on the reefs and seagrass meadows.

The marquinhets that retained their flight do not venture far out to sea and so have adapted their wings and body shapes to suit their particular hunting styles. In the case of the plunging marquinhet, the bird glides over the reef looking for shoals of fish. On finding them it hovers in place, surveying the scene before diving into the water. Like a gannet, it folds back its wings like an arrow to increase speed; unlike a gannet, the plunging marquinhet spends relatively little time pursuing its prey underwater. It tends to be more successful than not at catching its prey as it enters the water, helped by its forward-facing eyes, and so is more akin to a kingfisher.

Indeed, the plunging marquinhet would be ill-suited to underwater pursuit as its webbed feet are comparatively weak at swimming and its generally dark colouration is more obvious to fish beneath it in the water. The bird’s plumage is mostly black with a lighter, though still dark, grey underside. The wing edges are pale blue as is an arrow-shaped pattern on its back.

Not to be surpassed, the closely related sunset marquinhet is even more impressive. The bird’s wings and sides are black with a cream underside, tinged with oranges near the feet and throat. The majority of its head and back are pale blue with a golden band across its eyes that curves towards its chest, and a crown of bright yellow. This combination of colours is highly evocative of the majestic sunsets seen across the reef, giving the bird its common name. This extraordinary sunset plumage is limited to males in the breeding season, however, and for most of the year – or for females year round - the vibrant yellows are replaced with duller bronze. Still a sunset perhaps but one later in the evening.

Unlike its diving relative, the sunset marquinhet is a skim feeder, flying close to the surface of the ocean and quickly dipping its head beneath the water to catch a fish. The bird has large eyes to spot its prey quickly as if it were to pause its flight for even a moment it would fall into the water. Though that is not the most dangerous place for a marquinhet to be as the reef if full of predators to strange to dwell on in this little guide.

All species of flying marquinhets show low sexual dimorphism, the main differences being the slightly larger size of the females and display feathers in the tails of males. During the breeding season, males grow a plume of long, brightly coloured feathers. These feathers serve no purpose in flying, and indeed would be detrimental to swift movement in both air and water, but showcase the male’s fitness, that he can continue to thrive in spite of his flamboyant features.

Both males and females possess a structure similar to the rosette found at the corners of the beak of the distantly related puffin. In puffins it is a small disc, but in flying marquinhets this tissue passes over the top of the beak and extends backwards along the face in a thin band. This area is brightly coloured, often yellow, and appears highly sensitive with mates rubbing them together during courtship.