Songbirds around the world are experiencing population setbacks due to habitat alteration in both their breeding and winter ranges. It was therefore good news when Earthwatch teams working at the Conservation Research Initiative (CRI) in the Pantanal sighted two black-backed grosbeaks this past dry season, extending the known range of this migratory songbird.
Black-backed grosbeaks (Pheucticus aureoventris) have been reported in the western part of Mato Grosso do Sul, Brazil, but the Earthwatch sightings are the first records for the eastern part of the state. The two birds were seen in June and August, in shrubby areas between cerrado habitats and gallery forest at Fazenda Rio Negro, the ranch that is the study site for the Earthwatch CRI there.
"The importance is that they have never been described in this region before," said Dr. Reginaldo Donatelli (Universidade Estadual Paulista), the Earthwatch principal investigator exploring birds at the Pantanal CRI. "Even if they used to reach Rio Negro in the dry season, nobody has officialy described them there yet. Ornithologists believed they had a smaller range, more to the west."
The black-backed grosbeaks apparently foraged on the abundant seeds available in the Pantanal during the dry season, from June to October, sharing the bounty with other common finch-like birds. Among those found by Earthwatch teams were blue-black grassquits, sooty grassquit, rusty-collared seedeater, yellow-bellied seedeater,double-collared seedeater, white-bellied seedeater, and others. It is possible that the black-backed grosbeak sightings were related to an abundance of seeds this past season, but only future research will bear this out.
"We need much more evidence from other places in the same area to declare anything else for sure," said Donatelli. Earthwatch teams at the Pantanal CRI will continue their research on the region's bird populations, including black-backed grosbeaks. But this years findings is at least a welcome indication of the well-preserved habitat in the Pantanal and the biodiversity it supports.
"This bird prefers more preserved habitats," said Donatelli. "This is important, considering that Fazenda Rio Negro's neighborhood is quite a pristine area. We consider the grosbeak's presence an excellent indicator of preserved habitats."
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