White-bearded Antshrike (Biatas nigropectus)

However, even in 2003 it was considered to be a very rare species and it was not clear what habitat it used, or where searches should be targeted. Our field studies showed that in Argentina it is a bamboo specialist that only lives in Guadua bamboo, especially yatevo (Guadua trinii). That’s why we think a better name for this bird is “guyra yatevo”, which means, in Guarani, “bird of the yatevo”.

It is a medium sized (15-17 cm) insectivorous bird, in the Thamnophilidae family. The White-bearded Antshrike is sexually dimorphic (the male and female look quite different). The male has a black hood that covers the top of its head, from the back of the neck to under the eye and reaching the bill. Males have a crest that they erect when agitated (e.g. in response to playback, see photo below). From the back of the head to the beginning of the throat, males have a white beard that is sometimes fluffed out, as in the upper photo. The bill is ivory-coloured in both sexes and the legs are dull pale bluish grey although in some individuals they can be bluer than others (we don’t know why – maybe it’s related to age). In the male, below the white on the throat, there is a black bib that extends down to below the breast (in some males it is more extensive than in others). Below this, the belly is dull olive brown with slightly darker streaking in some individuals. In both sexes, the tail and wings are rufous.

In the female, a soft brown colour predominates, except in the tail and wings which are a more intense rufous. In contrast to the male, the female does not have a black bib. Instead, her breast is whitish to grey-brown. Both sexes have a white eyebrow. The male often hides it, but it is more noticeable in the female.

This bird’s behaviour, and the type of bamboo it inhabits, make it extremely cryptic (almost invisible). It keeps hidden in the high part of dense, continuous, mature patches of yatevo. It very rarely sings on its own – only at particular times of year (especially spring). So detecting this habitat specialist can be very complicated. We use playback to study it. Using this method, we’ve been able to find the White-bearded Antshrike in many patches of yatevo in northern and central Misiones.

Where does the White-bearded Antshrike live in Argentina?

In Argentina, the White-bearded Antshrike only lives in yatevo bamboo in the province of Misiones. There are five relatively common species of bamboo in Misiones. Two are in the genus Chusquea. Pitinga (Chusquea tenella) and Takuarembo (Chusquea ramosissima) are dense, low, and tangled. Takuarembo often climbs trees. There are two species in the genus Guadua. Takuarusu (Guadua chacoensis) is the largest bamboo with the biggest diameter culms. The second largest is Yatevo or Takuara Brava (also, confusingly, known as Takuarusu in San Pedro where we work). Takuarusu and Yatevo can be recognized by their big thorns. The fifth species is Takuapi (Merostachys claussenii). It is the most widely distributed bamboo in Misiones, but it recently underwent mass flowering and die-off in 2004-2007, so now it’s in an early growth phase with many small plants.

We have found more than 150 territories of the White-bearded Antshrike and they were all in Yatevo. However, other observers have mentioned finding this species in Takuarusu and in Yatevo mixed with Takuapi. In the latter case, we believe the species was there because of the Yatevo. We have found the White-bearded Antshrike as far north as Iguazú National Park and as far south as the Yaboty Biosphere Reserve, always in Yatevo bamboo.

Why is the White-bearded Antshrike threatened?

The main hurdle to conservation of the White-bearded Antshrike is the lack of information about its habitat requirements and biology. For this reason, there have been no policies that aim to protect its specific habitat. As you can see in the photo, Yatevo can form large and continuous patches even in places transformed by humans. We have found the White-bearded Antshrike in patches of Yatevo beside the highway, or within plantations or pastures where all the other forest was eliminated. This suggests that the White-bearded Antshrike can support a certain amount of deforestation as long as it has Yatevo. However, it is important to study how habitat fragmentation affects this species.

What are we doing to help the White-bearded Antshrike?

• We are searching for the White-bearded Antshrike in central and southern Misiones, to determine its distribution.
• We are studying its natural history and ecology.
• We give talks to park rangers and others involved in conservation in Misiones.
• In 2008-2009, we are presenting a puppet show starring the White-bearded Antshrike, in 14 schools from Paraje 45 to Santa Cruz del Monte.
• We have just printed 1000 copies of a poster about the White-bearded Antshrike and Yatevo bamboo, for local dissemination.

What else needs to be done for the White-bearded Antshrike?

It’s important to raise awareness about the importance of bamboo habitat for this and other species in the Atlantic forest. There is a need for environmental education focusing on the importance of native bamboo. Stands of Yatevo bamboo should be protected on farms, in private forestry lots, and in the Yaboty Biosphere Reserve. We should value this special microhabitat, so critical for the White-bearded Antshrike.

Long term studies should aim to understand the dynamics of Yatevo patches and how bamboo cycles affect this interesting bird. It Individual White-bearded Antshrikes probably depend on more than one patch of Yatevo, moving between them when the Yatevo structure changes. According to our predictions, Yatevo should flower and die throughout Misiones around 2018. This could drastically affect the population of White-bearded Antshrike. That’s why we think conservation plans for this species should aim to conserve Yatevo in protected areas but also in villages, farms, and everywhere it’s present.