Living the Scientific Life (Scientist, Interrupted)

tags: bpr3.org/?p=52, birds, Sincorá Antwren, Formicivora grantsaui, ornithology, Brazil

In a world where many humans believe they know the identities of every living thing on the planet, it is truly refreshing to learn that we have found yet another species of bird that is new to science. This new species was recently found in eastern Brazil. The bird was captured, studied and its vocalizations were recorded by ornithologists. The data collected from these birds, particularly this species' vocalizations, have been used to write a formal scientific description of this new species.

Even though this lovely little bird was first observed in 1997, it was not formally described as a new species until now. The Sincorá antwren, Formicivora grantsaui, is a small passerine in the family, Thamnophilidae, which are the typical antbirds. This new species' binomial name commemorates the German-born naturalist Rolf Grantsau, who originally collected a specimen in 1965 -- a specimen that was only just recently identified as being this new species.

According to the authors, the Sincorá antwren is found between 850 and 1,100 meters in elevation in the Serra do Sincorá of the Espinhaço Mountains. This area is in the Chapada Diamantina region in the state of Bahia, Brazil (figure 1, below);

These birds are small; weighing between 8.5-11.5 grams. The adult male Sincorá antwren has warm chocolate-brown upperparts and sides (see image at top). The bird's glossy black face, throat, breast and upper belly are beautifully contrasted with brilliant white. The lower belly and vent are pale silvery-grey. The upperwing-coverts are black with white spots while the underwing-coverts are grey and white. The tail, which is generally held erect, has brilliant white tips, a black subterminal band with charcoal grey base on the ventral side (see figure 8, below) and is a medium grey on the dorsal side (not shown). The bill is black and the feet are grey with yellowish soles.

Adult female Sincorá antwrens are paler brown on their upperparts than the males. They have a brilliant white face, throat, belly and vent with heavy black streaking (see image, below). Otherwise, they are similarly marked to the males.

Interestingly, the closely-related rusty-backed antwren, Formicivora rufa, is quite similar in appearance to the Sincorá antwren and its range overlaps with that of the newly discovered Sincorá antwren. However, the rusty-backed antwren looks different; having paler and more reddish (rufus) upperparts, yellowish sides and it has entirely white underwing-coverts. Additionally, these two species utilize different habitats where their ranges overlap and they also have very distinct vocalizations from each other and from other nearby antwren species.

In fact, the antwrens' vocalizations were so different that much of the scientific paper that describes the Sincorá antwren actually focuses on sonograms for this species, comparing them to several other closely related antwrens and using those differences as a strong argument for classifying these birds as separate species.

For example, antwrens are duetting species, which means that territory-holding males and females sing a duet together at the end of a singing bout, each sex having their own part to sing in the duet. As can be seen in these sonograms, the Sincorá antwren's duet (see figure 15, below) differs significantly from that of the rusty-backed antwren (figure 16, below) as well as from that of the closely-related white-fringed antwren, Formicivora grisea (figures 17 & 18);

Antwrens of both sexes also produce "loudsongs", which are an advertisement song that are sung alone, rather than as a duet. As can be seen, the loudsong of Sincorá antwren (see figure 19, below) differs significantly from that produced by the rusty-backed antwren (figure 20, below);

Antwren species have distinct alarm calls that are used when the bird is either afraid or when it is trying to re-establish contact with its mate (Sincorá antwren, figure 9; rusty-backed antwren, figure 10; Parana antwren, Formicivora acutirostris, figure 11; white-fringed antwren, figure 12);

Surprisingly, even these three antbird species' distress calls differ significantly (Sincorá antwren, figure 21; rusty-backed antwren, figure 22; white-fringed antwren, figure 23);

"This is potentially another new species for Brazil. Once confirmed, it is vital that we assess its conservation status and any potential threats. It would be sadly ironic if, as soon as it was discovered, Sincorá Antwren became threatened with extinction," observed Stuart Butchart, who is the Global Species Program Coordinator for BirdLife.

I personally am very excited about this discovery, especially since this is a fascinating group of birds. For example, I would love to know more about the phylogenetic relationships between these birds and use that to make analyze the evolution of song and color patterns in this group of birds.

This discovery was published in the journal, ZooTaxa.

Sources

"A new species of Formicivora antwren from the Chapada Diamantina, eastern Brazil (Aves: Passeriformes: Thamnophilidae)" by Luiz Pedreira Gonzaga, Andre M. P. Carvalhaes & Dante R. C. Buzzetti. Zootaxa 1473:25-44 (2007)
[free PDF]. (images).

BirdLife (quote).