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Zino's Petrel: Lost and Found
Listen nowIt's approaching midnight and we're standing on a knife-edge mountain ridge. It's cold, dark as pitch, and windy. Eerie clouds swirl around us, making it impossible to see more than a couple of yards. We huddle on the dangerously narrow path, looking for shelter among a few boulders as squalls of powdered soil sting our faces.
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| Zino's petrels on Madeira. (Francis Zino/Freira Conservation Project) |
This is my first visit to Madeira, a 450-square-mile Portuguese island that lies 400 miles off the west coast of Morocco, and ornithologist João Nunes is guiding me on my nocturnal expedition. We can barely make out the gloomy shape of the pock-marked cliffs behind us, and I am thankful that their precipitous slopes and deep, gouged valleys are left to our imagination. Aside from the wind, all has been silent since we walked onto this summit-ridge path on Pico do Areeiro an hour ago.
Then, we hear a ghostly wail from somewhere in the dark sky around this mountain peak. And another, this one from a different direction. The shepherds who once grazed their goats on these hillsides say they are the cries of colleagues who have fallen off Madeira's ancient, volcanic mountains to their deaths. The sound is surreal, as if someone is trying to frighten us.
"That's it. That's their call," whispers Nunes. "The adults are flying in to locate their breeding burrows." The mysterious sounds do not belong to spirits, but to Zino's petrels (Pterodroma madeira), Europe's rarest breeding seabirds. There might be 80 breeding pairs of these gray-and-white birds on this Atlantic island, and they breed nowhere else in the world.
Every night, whether the skies are clear or veiled by dense clouds, each pair of petrels flies in from the sea, gains thousands of feet in altitude, and lands near its burrow. Ungainly on the ground, the birds shuffle the last few feet to their burrow's entrance to find and feed their solitary nestling.
The story of the Zino's petrel's discovery, presumed extinction, and rediscovery, coupled with its mysterious lifestyle, is extraordinary. But it's more than a fascinating tale. The threats this petrel faces, and the efforts to conserve and enhance its small population, mirror those of other island-breeding seabirds worldwide.
Zino's petrels are delicate birds with 32-inch wingspans and 13-inch-long bodies built for gliding over the ocean for long periods of time. It's hard to believe that such small seabirds fly up over steep valleys and navigate their way, in darkness, to nest among sheer rock pinnacles.
Pairs select a nesting site in late March at the beginning of the breeding season and begin constructing four-foot-long burrows in the cliffsides. "The birds dig them themselves, where there's friable soil, into very steep slopes," says Frank Zino, a doctor and ornithologist who is the son of the species' namesake. "You can always tell when you have young, prebreeding birds, because their nails are sharp enough to scratch you," he says. "On breeding birds, the nails are always blunt from digging."
Between mid-May and June, the female Zino's petrel lays a single white egg at the end of the burrow on a fairly rudimentary nest composed of pieces of grass. Each parent incubates the eggs for several days without eating, then trades places with the other parent.
The chick hatches at the end of July or early August. Tucked well inside a burrow set among rocky ledges, yellow-flowering broom, and desiccated grasses, it spends the first few months of its life totally isolated from the sea.
By early- to mid-October, the growing chick feeds only every two or three nights. Then one night, it leaves its burrow under cover of darkness. On Madeira, all of the known nesting burrows face roughly northeast, the direction of the predominant winds. Presumably, that gives an increased chance of lift—and survival—to young Zino's petrels making their maiden flight to the sea.
The Zino's petrel might have been known to science earlier, but for a case of mistaken identity. In 1903, a few of the birds were brought to Father Ernesto Schmitz, a priest and naturalist who lived on Madeira. He misidentified them as Fea's petrels (Pterodroma feae), which have similar plumage to Zino's petrels, but are bigger and heavier birds with larger bills. Fea's petrels breed in small numbers on Bugio, an island 15 miles southeast of Madeira, but not on Madeira itself.
Father Schmitz left Madeira five years later, and memories of a petrel nesting high in Madeira's mountains faded. No one reported seeing or hearing the birds, and they were presumed extinct.
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| Zino's petrel habitat on Madeira. (Francis Zino/Freira Conservation Project) |
But in 1940, a young petrel that may have been disoriented by the lights of Madeira's capital, Funchal, was found dead on the grounds of the governor's palace. Frank Zino's father, Alec, an amateur ornithologist and owner of a small property business on Madeira, was familiar with Fea's petrels and he knew this bird was different. When he inspected another of the mysterious petrels that was found in Funchal in 1952, he was convinced he was looking at a new species, possibly the one Schmitz had examined 50 years before. "He was also sure that they weren't Fea's petrels because these fledged youngsters were found in October," says Frank. On Bugio, Fea's petrels don't fledge until December or later.
Alec Zino wasn't the first person to suggest that Father Schmitz had made a mistake. In a study published in the Bulletin of the British Ornithologists' Club in 1934, Australian ornithologist and petrel expert Gregory Mathews compared preserved Fea's petrel skins with those of the birds taken to Schmitz earlier that century. Mathews suggested that the two were sufficiently different to be separate subspecies.
Inspired by his examinations of the dead birds and Mathews' study, Alec visited Madeira's high mountains numerous times in the mid-1960s to listen for any calls that might be petrels. But he heard nothing. Perhaps, he thought, the birds had died out. Then, another possibility crossed his mind: If the birds breeding on Madeira were so physically similar to Fea's petrels that a man of Schmitz's experience could confuse them, then both birds' calls might be similar as well. So he recorded the calls of Fea's petrels on Bugio as they came in after dark to find their nesting burrows, and played the recordings for shepherds who grazed their sheep and goats on Madeira's mountains.
A shepherd named Lucas recognized the calls and said he knew where they could be heard. In April 1969, Lucas took Alec to the ridges where the petrels were breeding and they heard the ghostly, nocturnal wailing, confirming that the birds still existed. By mid-June that year, they found burrows with eggs.
Alec and Frank studied the birds, and in 1986 published a paper in Boletin do Museu Municipal do Funchal proclaiming that Madeira's petrels belonged to a species separate from Fea's petrels. The distinction was accepted by the scientific community.
Scientific names were created for the birds, but their common names were a different matter. In Portuguese, the petrels of Madeira were known as the freira, while Fea's petrels were called gon-gon. "But then we needed English names," recalls Frank. Fea's petrel was agreed upon for the Bugio birds. Alec and Frank proposed the name "Madeira petrel" for the other species, but it was too similar to the name of the Madeiran, or band-rumped, storm petrel (Oceanodroma castro), a very different-looking seabird. "So Bill Bourne [a leading British ornithologist and seabird expert] kindly suggested the name Zino's petrel in honor of my father. And the name stuck," says Frank.
Alec Zino died in 2004. He is generally referred to as the man who rediscovered Zino's petrel, and the original discovery is attributed to Schmitz despite his misidentification of the bird.
How many Zino's petrels are there? It's difficult to count them; their habitat is inaccessible, and the adults come to land only after dark.
In the first systematic monitoring of Zino's petrel burrows, in 1986, only one nesting area with six occupied nests was found. Since then, the number of occupied burrows found in the original surveyed area has increased, and other nesting areas have been found. Today, there are six known nesting areas occupied by an estimated 60 to 80 breeding pairs.
According to Frank, who counts and studies the birds, new nesting sites may yet be discovered. With other ornithologists and conservationists, he has been putting identification bands, or rings, on all the young petrels found in burrows for several years and banding adult birds caught in mist nets at night. "But we are still catching some young adults that aren't sexually mature and are not ringed," he says. "These must be birds reared in burrows we haven't yet found. So there could be other breeding areas and perhaps we have more than 80 pairs."
If Zino's petrels are something of an enigma during the breeding season, where they spend the bulk of the year at sea is totally unknown. "Some American birders have told me that they've seen them off the east coast of the U.S. in winter," says Nunes. "But I think it's impossible to tell Fea's and Zino's apart when they are in flight over the sea, so I'm not convinced. They could be anywhere out in the Atlantic, maybe farther."
While the Zino's petrel's wingspan and body are a bit shorter than the Fea's petrel's, and its beak is a bit slimmer, these differences are hardly noticeable in flight. The crown and forehead of the Zino's petrel is a little paler than the Fea's, but try assessing that from a boat heaving in choppy seas while the bird skims low, twisting and turning with every motion of the waves.
Madeira wasn't always as it is today. The island was discovered in 1419 by the Portuguese explorer João Gonçalves Zarco, who spied it from his landing site on Porto Santo, an island about 30 miles to the northeast of Madeira. Zarco, whose statue graces a square in Funchal, named it Ilha da Madeira (Island of Wood) because of its dense cover of shrub-rich laurel forest.
When Madeira was uninhabited, its seabirds, including Madeiran storm petrel and the Cory's shearwater (Calonectris diomedea), probably nested in burrows on forested slopes. Today, they still breed on slopes above the sea, although no trees grow there. The island's few hundred Manx shearwaters (Puffinus puffinus)—seabirds similar in size to Zino's petrel—continue to breed on forested slopes farther inland. Maybe some or all of the Zino's petrels excavated their burrows on forested slopes, too, and were more commonplace than they are today.
Fossilized bones matching today's Zino's petrels have been found on several parts of Madeira and on the neighbouring island of Porto Santo. Some were found in caves at lower elevations, suggesting that mountaintop breeding might be a relatively recent development. "Why they now breed exclusively so high up we don't know," says Frank. "Perhaps they moved up to get away from human disturbance, or from yellow-legged gulls [Larus cachinnans], which predate on young shearwaters and petrels breeding on low ground, or even perhaps from shepherd dogs."
Designed for life at sea, petrels and shearwaters are marathon fliers, wheeling and soaring between the waves on the lookout for small squid, surface crustaceans, and fish. They are also good swimmers. But on land, they are the archetypal "ducks out of water"; an ungainly, slow shuffle is all they can manage. They are so vulnerable to nocturnal land predators when they walk on the ground that they land as close to their nest entrances as possible.
For centuries after Madeira's discovery, seabirds and their eggs—including, presumably, Zino's petrels—have been eaten by introduced species. Black rats (Rattus rattus) escaped ships and soon became established in the countryside, where ground-nesting seabirds and their eggs were an obvious source of summertime food. Cats, imported by the early settlers and popularly kept as pets on Madeira, frequently became feral and also preyed on seabirds. In the high mountains, too many sheep and goats have trampled the burrows of the Zino's petrel and eroded the steep slopes where they nest. In recent decades, egg collectors—attracted by the bird's rarity—have also taken their toll.
Predation and habitat destruction steadily reduced the population. "All through the 1960s, '70s, and '80s, the breeding success of the known nesting sites was terribly low," comments Frank. In 1986, when systematic monitoring of the few breeding ledges that were known at the time began, none of the young birds survived the summer, and rats were strongly suspected as the killers. In 1991, feral cats killed ten adults in one breeding area. "Luckily, these petrels, like most other seabirds, are very long-lived. [Some petrels live up to 50 years.] Otherwise, I believe that the level of predation would have driven them to extinction."
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| Frank Zino working with a Zino's petrel. (Francis Zino/Freira Conservation Project) |
In 1986, the Freira Conservation Project—a joint initiative among the Funchal Museum of Natural History, the Natural Park of Madeira, and the local community—was created to attract funding for regular monitoring of the birds and for predator control programs. Since the project's inception, poison baits have been put out to kill rats and feral cats have been trapped. These controls remain in place, as rats from lower ground replace those poisoned at higher elevations, and domestic cats are released into the hills by owners who no longer want to care for them.
Predator control is allowing Zino's petrel to prosper. Breeding success has increased, and few youngsters are now lost to rats and cats. Similar success was achieved with other rare island-breeding petrels, including the Bermuda petrel (Pterodroma cahow) and the Hawaiian petrel (P. sandwichensis). Both of these rare seabirds had nearly succumbed to introduced predators including rats, cats, dogs, and mongooses.
According to Isabel Fagundes, director of the Portuguese bird protection organization Sociedade Portuguesa para o Estudo das Aves, almost all of the seabird species that breed on Madeira and other offshore islands are increasing. "All the rats have been poisoned by the Madeira Natural Park Authority on the Desertas Islands and in the Selvagem Islands," which are 165 miles south of Madeira, she says. "These are very important places for a range of breeding seabirds. Their numbers are now increasing." Completely eradicating rats on a large, mountainous island like Madeira is impossible, and docking ships are likely to reintroduce them time and again. So, baiting and trapping around the Zino's petrel's breeding sites continues.
About 750 acres of the mountaintop area in which Zino's petrel breeds have been purchased by Madeira's Regional Government to ensure the species' protection. And Madeira's central mountains and laurel forests comprise a large portion of the 65 percent of the island set aside for conservation by the Madeira Natural Park Authority and protected by European Union conservation laws.
Shepherds are now banned from grazing goats and sheep on the highest land and a large area has been fenced, with grids on access roads, to keep them out. "The shepherds were compensated," says Fagundes. Frank and his colleagues from the Madeira Natural Park Authority who monitor the petrels have noticed a massive recovery in the mountain vegetation now that no livestock graze these topmost slopes. Erosion has declined, also.
Frank thinks that these factors could encourage the petrels to increase their numbers and extend their breeding to several mountain areas they do not currently inhabit. While it's impossible to know whether these new areas suit the Zino's petrel's precise breeding needs, conservationists are thinking about making them more attractive for nesting by installing artificial breeding tunnels, something that has been done successfully for some of the world's other rare petrels.
What's it like, I asked Frank Zino, to have a bird named after your family? "It's pretty exciting," he replied. "I feel a great sense of responsibility, but it's a fantastic honor, too." There's no doubt that Alec and Frank Zino's work has helped give the petrel much better prospects than it has had for a few hundred years.
—Malcolm Smith is chief scientist and senior director of the Countryside Council for Wales in the United Kingdom.
ZooGoer 36(1) 2007. Copyright 2006 Friends of the National Zoo. All rights reserved.
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