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Biodiversity

The Cerrado falcons

Countryside reveals unexpected biological wealth

JOSÉ CARLOS MOTTA JUNIORFound only in the Cerrado (savanna) habitat: the white-rumped tanager or Cypsnagra hirundinacea, endangered speciesJOSÉ CARLOS MOTTA JUNIOR

A landscape like a wide abandoned pasture, with an occasional tree here and there, under the scorching sun of inner-state Sao Paulo now appears to be a remarkable open air bird sanctuary. The Cerrado (Savanna) of the Itiparina Ecological Station, 230 km from the city of São Paulo, houses 231 bird species, including delicate birds the size of a hand, the curl-crested jay (Cyanocorax cristatellus), 17 falcon and hawk species, and seven types of owl, predators at the top of the food chain, almost as if they were winged lions, plus the rhea, Brazil’s largest bird, which can be as tall as 1.8 meters. Within the 23 km2 of this open field – an area equal to 1% of the Brazil’s Federal District, the heart of the Brazilian savanna – lives one out of every three species  found  only on savannas, 27% of the total species found in this kind of environment and 30% of the species recorded in the entire state of São Paulo.

Not even the biologists expected to find such biological diversity in previously underrated vegetation because it was the “barest” form of savanna – a clear open field (which is rare in São Paulo) covered with sandy soil and nothing other than small plants and bare fields,  a few bushes sprouting here and there on this green “carpet”. How can this be explained? José Carlos Motta Jr., a professor at the University of São Paulo (USP), says that it is precisely because this is an open field that there is such a significant variety of winged species born and growing in the area, many of which are endangered in the State of São Paulo. With a little bit of patience, one can also see some of the 33 migrating species that have already been identified, such as a rare osprey (Pandion haliaetus) from the south of the US. Many others may never be seen if the savanna disappears, warned two bird experts, Edwin O’Neill Willis and Roberto Cavalcanti, almost twenty years ago.

Motta Jr. started going out at night to see and hear the owls in the region’s woods and savanna at the age of thirteen. He is a member of the team of almost 30 biologists from USP, from the State University of Campinas (UNICAMP) and from the Butantan Institute, who spend their days and nights searching for  life in the sky, in holes in the ground or even in the dead trees of the Itirapina savanna. The wildlife census currently under way, after ten years of work, also shows new species and phenomena. This is the case of the Clyomys bishopi, a 20-centimeter rodent (without the tail) found only in this area, which builds interlinking tunnels half a meter down from the surface. They live in colonies and are possibly a key-species. Biologist Roberto Guilherme Trovati found that these animals store and spread fruit and seeds; they are also food for other animals, and build shelters that house lizards, snakes and frogs.

Other conclusions may also be useful to review or strengthen natural vegetation conservation strategies. “We have lost the romanticism of believing that there is only one solution to preserving all animal groups,” says Márcio Martins, a professor from USP’s Institute of Biosciences and team coordinator. “It is no longer about choosing between ponds full of endemic frogs or an open field in which certain birds that do not accept other spaces live, but about keeping both environments, since they are equally important.” Biologists from this group found that clearings hinder most animal species, such as the Leptodactylus furnarius frog, which practically only lives in the preserved savanna, but others may even profit from clearings, such as the rattlesnake and the burrowing owl, which spread and easily reproduce in open areas.

Grasses and hunters
Surveys show the precarious circumstances of the São Paulo State savanna, which is surrounded by farms and cities, but is among the few in the country that still have clear open fields. In other areas there are sinuous hard trunk trees that withstand frequent fires; these are savanna fields, with trees such as the pequi (Caryocar brasiliense), whose fruit people from Brazil’s midwest add to rice, and the gabirobeira (Campomanesia adamantium), whose fruit goes into sweets and jellies. Usually, bushes along river banks cover 10% to 15% of Brazil’s savannas, but in Itirapina, the percentage is below 5%; and it is precisely in these bushes that a significant number of birds and most amphibians live, aside from the amphibians that only reproduce in these bushes. The recomposition and integration with the bush areas close to the rivers is one of the researchers’ recommendations that will be given to the ecological station’s management,  to provide further husbandry of the natural spaces of the giant anteater (Myrmecophaga tridactyla), the cougar (Puma concolor) and the otter (Lontra longicaudis). They suggest improving surveillance against poachers and cattle invasion, from whose feces  seeds of invading grasses are spread, besides paying more attention to the elimination of exotic trees, especially pines, that invade the station and grow from seeds blown by the wind from neighboring reforestations. “The pine trees have advanced significantly upon other savanna preservation areas in the state of São Paulo,” says Motta Jr.

JOSÉ CARLOS MOTTA JUNIORRarity: the capped seedeater (Sporophila bouvreuil pileata), critically endangeredJOSÉ CARLOS MOTTA JUNIOR

Some time ago, based on this information and the conclusions drawn from the field surveys, the station’s management and the researchers took the joint decision to deactivate the internal roads, to foster biological diversity. When former station manager Denise Zanchetta needed arguments to support her fight for the annexing of  a neighboring 150-hectare savanna field that belonged to the state, she did not hesitate to call the São Paulo biologists who frequently visited the station. “Working together and making decisions that benefit everybody is a very comfortable and rich experience,” she says. “There is a vacuum in most cases. The researcher comes and goes, leaving nothing behind, and the manager is seen merely as someone who will stand in the way of scientific work.”

Everything seems quiet in these surroundings, yet it is very similar to an unstoppable food feast even among the representatives of the top of the food chain: a large hawk can attack an owl, and a large owl can eat a small hawk. Motta Jr. says he once saw a ferruginous pygmy-owl, Brazil’s smallest owl, weighing approximately 60 grams (less than a thrush), eat a 30-gram bird, the fork-tailed flycatcher (Tyrannus savanna). However, it is important avoid staring only at the sky, for there are several snakes there as well. Martins, Ricardo Sawaya (a Butantan biologist) and other members of the team that studied reptiles asked people from the neighboring farms to keep the snakes found in the plantations, fields and houses, which they killed. Most of the 35 species seen in the reserve also lived on the farms, indicating that they survived the extreme temperature, humidity and vegetation variation. Only three less flexible species – a lance-head (Bothrops itapetiningae), a false coral (Oxyrhopus rhombifer) and the “nariguda” (Lystrophys nattereri) – lived exclusively on the preserved savanna.

In other cases, while the bird team searched for stool samples, from which they were able to discover what the animals fed on, the reptile team opened the stomachs of dead snakes to find out how many frogs, lizards and rodents they had eaten. In one of the studies, Felipe Spina made nine hundred 20-centimeter snakes out of play dough (300 with red, white and black stripes, representing the corals, 300 with angled stripes and another 300 totally brown ones) to see whether hawks and owls refrained from attacking the play dough snakes with strong colors, which represented the poisonous species and their exact imitators. And yes, they do avoid them, and prefer the brown ones, which represented the non-poisonous species.

One of the conclusions of this study was that in the savanna, as had already been found in Central America tropical forests, one way of living a few extra months was to seem poisonous: even a superficial similarity to a real, poisonous coral snake already sends predators on their way. Hawks, owls, jays and herons are unable to distinguish the false coral snakes (non-poisonous) from the real ones, since both are colored. When in doubt as to which would in fact be poisonous – the mistake could result in their death – predators look for other food. Thus, the real coral snakes, though rare in Itirapina, aid the other colored snakes. “It’s involuntary altruism,” says Martins.

Biologists have also found out some of the preconceived ideas that go hand in hand with certain species, such as the maned wolf (Chrysocyon brachyurus). Although it is the only wolf in Brazil that feeds primarily on fruit and rats, and occasionally on partridges, people from the region believe they love to prey on chicken and other domestic animals, which is untrue. According to the survey, the maned wolf attacks one chicken for every 50 to 70 rats it eats. “If people fence the pens or place a dog nearby, the maned wolf leaves,” Motta Jr. suggests. “It is not like the gray wolf, which can even eat a dog.”

The Projects
1.
Natural History, ecology and the evolution of Brazilian vertebrates; Type Thematic Project; Coordinator Márcio Martins – IB/USP; Investment R$ 815,289.80 (FAPESP)
2. Ecology of land vertebrate communities in Cerrado (savanna) habitats and altered areas in the region of Itirapina, state of São Paulo; Type
Regular Research Awards; Coordinator Márcio Martins – IB/USP;
Investment R$ 4,8954.88 (CNPq)

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