guia do novo coronavirus
Imprimir Republish


Trip of No Return

Female Magellanic penguins are more likely than males to die during the annual migration

Fragile animals: Animals in captivity like this one are vulnerable to avian malaria

Eduardo CesarFragile animals: animals in captivity like this one are vulnerable to avian malariaEduardo Cesar

Over a period of seven years, biologists and veterinarians from the states of São Paulo and Rio Grande do Sul collected 528 Magellanic penguins from the beaches of Brazil’s extreme southern region. Most of them were alive, although many so weak that they would die soon after. Others were already dead, their bodies decomposing. When their genders were determined in a laboratory, it was found that the majority of the dead animals and those that died during rehabilitation were female, perhaps because they were weaker than the males. The unexpected finding represented a possible explanation for the surplus of males in the colonies of penguins of that species, a phenomenon that was fairly well known, but never fully explained.

Many penguins are also dying of avian malaria, a disease that worries the experts because climate changes could expand the geographical distribution of the mosquitoes that transmit it into areas close to the penguin colonies. Avian malaria has also been a threat to penguins that are in captivity or undergoing rehabilitation, since many animals had a low resistance to infections when they arrived. In 2007, malaria struck four of the five Magellanic penguins—all female—at the São Paulo zoo; two died as a result of the infection and the others died of other causes. Today, the Sabina Escola Parque, in Santo André, is the site where the largest numbers of penguins of that species are found in greater São Paulo—they number 23, perhaps 24 this year if the first chick is born. After four years of work, the biologists and veterinarians who manage the aquarium seem to have found the best conditions for developing a fertilized penguin egg.

Magellanic penguins (Spheniscus magellanicus) reach an average height of 70 cm, can weigh as much as five kilograms (kg), and are usually identified by a collar of white feathers around a neck covered with black feathers. Another peculiarity: they don’t like the cold, in contrast with other species, such as the famous Emperor penguin, which can be as tall as 1.20 meters, weigh 35 kg, and has yellowish patches around its head. Every year the Magellanic penguins form colonies—often with more males than females—breed, and hatch their chicks in the dry regions of southern Argentina and Chile. It is estimated that the population of Magellanic penguins totals about 3 million, distributed in colonies that have up to 100,000 pairs. In April, when the temperature drops and food becomes scarce, hundreds of penguins dive into the water in pursuit of schools of fish and begin to travel an erratic route. They will swim thousands of kilometers northward for months, through the cold waters of the Malvinas (Falkland) current.

Many die at sea, while others are still alive when they reach the Brazilian coast. Some have traveled so far from the band that they have been seen as far away as the coast of the state of Ceará. Those found on the beaches of Rio Grande do Sul are almost always dead, or nearly so, owing to exhaustion. “In general, the penguins that survive the trip are dehydrated and hypoglycemic, and can’t even raise their heads, reports Ralph Vanstreels, a researcher at the School of Veterinary Medicine and Zootechny of the University of São Paulo (USP). “Some, covered with oil that leaked from ships, are just waiting to die.”

056-059_Pinguins_215Petroleum is one of the leading causes of death among these animals. Along the coast of Chubut province in Argentina, oil tankers wash out their tanks and discard the residue into the ocean, causing the death of 20,000 adult penguins every year. Other penguins die because they consume garbage that has reached the ocean. Researchers from Rio de Janeiro found plastic residue in the stomachs and intestines of 15% of the 175 Magellanic penguins found dead in the region of Lagos, along Rio’s coast.

Collected from 2002 to 2009, the 528 Magellanic penguins that Vanstreels examined may provide some answers about the habits and mortality of the animals during their annual migration. He and the technical staff of the Marine Animal Rehabilitation Center at the Federal University of Rio Grande (Furg) traveled an average of 200 km per day, aboard a pickup truck, collecting animals on the beach near Lagoa dos Peixes in the municipality of Rio Grande. The live penguins were placed in cages and taken to the rehabilitation center, where they were bathed, fed, and medicated. The dead ones were sent for analysis and gender identification.

Penguin Gender
It is not easy to tell the difference between male and female Magellanic penguins, which at first appear to be very similar. Vanstreels cites as example the beaks of the males, which are slightly broader and only a few millimeters bigger than the beaks of the females. When the animal is dead, it is even more difficult to distinguish gender because of the state of decomposition, which leaves some without a beak. In those cases, researchers use genetic markers or simply cut open the carcass to find either testicles or ovaries.

Of the 409 animals found live on the beach, 211 have died. Of these, more than half (126) were female. Among the 118 found dead, 88 were females. Researchers believe that the population growth of penguins of that species is slowing because apparently, more females than males die during the migration. Since penguins are monogamous, it is likely that many are left alone. According to Vanstreels, in Argentina, males without partners have been observed picking fights with those that have formed couples, very often breaking the eggs in the nests.

Colony of penguins in southern Argentina

RALPH VANSTREELSColony of penguins in southern ArgentinaRALPH VANSTREELS

Vanstreels and his doctoral advisor José Luiz Catão-Dias believe that the larger number of females found dead is due to differences in the food-search strategy adopted by males and females during migration. When there is more fish, all of them hunt in the same way, i.e., in the regions of the ocean closer to the surface. The differences appear when food becomes scarce. According to Vanstreels, the males probably dive into in the deeper regions for fish, while the females remain closer to the surface, swimming in wide circles. Because they swim in a larger area, Catão-Dias explains, they may be more vulnerable than the males to pollution from petroleum.

Overfishing of small fish like sardines and Argentine anchovies, the favorite foods of Magellanic penguins, may be one of the reasons behind the food scarcity that forces them to swim deeper, in the case of the males, and for longer distances, in the case of the females. Researchers from Vale do Rio dos Sinos University (Unisinos), in Rio Grande do Sul, determined that the young penguins found dead on the beaches had very little fat under their skin, and that their stomachs contained only remnants of shellfish, which have little nutritional value.

Researchers suspect that the females may have already been weak when they left the colonies. On a visit to penguin colonies in Patagonia, Vanstreels and Catão-Dias observed that male chicks would steal from the females food that the parents had brought for both their chicks. “It’s possible that the females are leaving the colonies in worse physical shape than the males,” Vanstreels suggests. It is not yet known how many penguins leave the colonies every year, or how many manage to return.

At the Zoo
Biologist Karin Kirchgatter, currently with the Malaria Laboratory at the Endemic Diseases Control Authority of the São Paulo State Department of Health, was one of the persons responsible for diagnosing the health of penguins infected with avian malaria in 2007 at the São Paulo zoo. Veterinarian Marina Galvão Bueno, now affiliated with the Mamirauá Institute in Amazonia, oversaw the treatment of those animals. According to Kirchgatter, even before presenting the initial symptoms, some of the penguins had been diagnosed with an inflammation caused by bacteria on their feet, probably developed because they had spent a lot of time outside the water as a way to avoid contact with disease-transmitting mosquitoes. That is why, she says, they were released to swim at night—which was when they were infected by the Plasmodium relictum parasite, transmitted by the nocturnal Culex mosquitos. “The penguins we were able to treat in time that did not die of malaria ended up dying a little later from, among other things, aspergillosis,” says Kirchgatter, referring to a lung infection caused by a fungus.

One of the animals in the Santo André aquarium

Eduardo CesarOne of the animals in the Santo André aquariumEduardo Cesar

Months after the first signs of malaria appeared, all five penguins were dead. After that, the zoo decided not to keep other animals of that species because of the high risk of infection. “Any place or plant that accumulates water can serve as a breeding ground for mosquitos,” says Kirchgatter, who is coordinating a project to identify plasmodium spp among birds at the zoo. Under Kirchgatter’s guidance at USP’s Institute of Tropical Medicine, biologist Carolina Chagas has collected about 800 samples of blood from almost 100 species of birds and identified one species of the protozoa, Plasmodium nucleophilum, different than the one that caused the death of the penguins but equally fatal.

Vanstreels and Catão-Dias found another rather rare species, Plasmodium tejerai, in two Magellanic penguins that died in 2009 at a wild animal triage center in Santa Catarina. Until then, the parasite had been identified only once, more than 30 years ago, in birds from Venezuela.

Studies like these indicate how to deal more effectively with Magellanic penguins and prevent diseases from getting to the colonies: after they are treated at the rehabilitation centers, the animals are released into the sea again. “The release of the penguins into nature should follow stricter criteria as regards the health of the animal, which includes preventing infected individuals from being released and fostering the transmission of pathogens among the animals in the colony,” Catão-Dias says. “The less time those animals remain in recovery, the lower the chances they will be infected.”

1. Avian malaria and penguins in Brazil: epidemiological and pathological study of a disease that poses a potential threat to the conservation of avifauna (nº 10/51801-5); Grant mechanism Thematic Project; Coord. José Luiz Catão-Dias/FMVZ-USP; Investment R$ 665,198.08 (FAPESP).
2. Plasmodium spp. in wild birds from the São Paulo Zoo: species identification by microscopy and DNA barcoding (nº 12/51427-1); Grant mechanism Regular Line of Research Project Award; Coord. Karin Kirchgatter/Sucen-SES/SP, Investment R$ 52,328.50 (FAPESP)

Scientific Articles
BUENO, M. G. et al. Identification of Plasmodium relictum causing mortality in penguins (Sphenicus magellanicus) from São Paulo Zoo, Brazil. Veterinary Parasitology., vol. 173, No. 1-2, pp. 123-27- 2010.
VANSTREELS, R.E.T. et al. Female-biased mortality of Magellanic Penguins (Sphenicus magellanicus) on the wintering grounds. Emu. vol. 113, No. 2, pp 128-134. May 2013.