Yunguilla

Yunguilla

The Yunguilla Reserve was established to protect the last remaining population of the Pale-headed Brush-Finch (Atlapetes pallidiceps), which was rediscovered here by Niels Krabbe (a founding board member of the Jocotoco Foundation) and Anna Agreda and Orfa Rodgriguez of CECIA/Aves y Conservacion in 1998 after being feared extinct for over two decades. Ninety-four percent of the entire Brush-Finch population is found inside the reserve, so the current survival of the species is completely dependent on management by the foundation. Like Utuana and Yanacocha, the Yunguilla Reserve serves to illustrate how important even small reserves can be, when strategically placed to protect site-specific biodiversity.

The reserve is situated in the Yunguilla Valley, 50 km south-southwest of Cuenca in Azuay Province. It spans elevations ranging from 1600 to 2000 m, and has very steep slopes with frequent landslides. The first 27 ha were purchased in 1999, and the reserve now measures 160 ha (395 acres). Most of the slopes are open and bushy, but about a fifth of the reserve is covered by humid forest, about a sixth by grassland, and about a seventh by stands of Chusquea bamboo. Smaller parts on the lower slopes have patches of dry forest. The Brush-Finch favors open bushy slopes with few trees, and stands of bamboo. In the dry season it moves into habitat with water and shade during the heat of the day, thus making some use of the copses of humid forest.

The valley has a pleasant climate and is a favored site for luxurious weekend residences, given its proximity to Cuenca. Despite high land prices in the area, a single anonymous donor has provided nearly all the funding for this reserve.  This is an important example of how private individuals can make a significant contribution to conservation, which in this case has saved the Brush-Finch from extinction.

In order to avoid unnecessary disturbance, visiting the reserve is confined to a single trail. On an early morning walk you will almost certainly see the Brush-Finch. You might also spot the Little Woodstar, another threatened species breeding in the reserve. Males turn on their perches atop the tallest trees on ridges to display their spread gorget in the sun, from time to time shooting high up and swooping down. Some years the Amazonian migrant Black-and-white Tanager, also considered threatened, nests in dry forest just below the reserve and can be heard or seen from the trail. The little-known Buff-fronted Owl is rare and inconspicuous, but sometimes sings (March, April) in the forest just before the entrance to the reserve, occasionally even by day. Several nesting boxes for it have been placed in the reserve, so far without success. A pair of Black-chested Buzzard-Eagle nests in the reserve, and is often seen soaring over the ridge. Although the Blue Seedeater is fairly common in bamboo thickets, it is shy and difficult to see. Pacific Elaenia and Line-cheeked Spinetail, both Tumbesian endemics, are fairly easy to find along the trail, as is a form of Amazilia Hummingbird (Amazilia amazilia azuay) endemic to this valley system and only described by Krabbe and Ridgely as late as 2010. In recent years a distinctive form of Rainbow Starfrontlet with a blue central crown and endemic to the Cajas plateau (Coeligena iris hesperus) has become a more regularly visitor to the reserve from the slopes above, and can now even be seen at the feeder by the park ranger’s house. Most bird song is heard in the rainy season, late February through April, and the Brush-Finch is much easier to detect at this time of year. Two recently discovered and still undescribed species of frog in the genera Gastrotheca and Pristimantis are so far only known from the reserve.

Rediscovery of the Brush-Finch:

After several futile searches for the Pale-headed Brush-Finch in likely locations by Niels Krabbe and by four other teams of researchers during the 1990s, Krabbe led an expedition in November 1998 to search for the species one last time before considering it extinct. The expedition was funded by American Bird Conservancy and planned with help from the BirdLife partner CECIA (now Aves y Conservación), and resulted in the miraculous discovery of a small population in the Yunguilla Valley on 16 November 1998. Finally knowing the habitat of the bird, the expedition continued with raised hopes to search in other parts of the valley system, but to no avail. Additional searches in the most suitable areas in the valley system in subsequent years, using playback of the species’ voice, seem to confirm that the only surviving population is that in the Yunguilla Valley.

The population has been monitored annually by Krabbe 1999-2009, and studies of its biology have been carried out since 2002, principally by Steffen Oppel, Martin Schaefer and Mery Juiña, with the result that the species today is the best known in the genus. Oppel found that brood parasitism by Shiny Cowbird (Molothrus bonariensis) was alarmingly high, affecting nearly all Brush-Finch nests in a large part of the reserve. Cowbird parasitism has been reduced to near zero from 2003, and the size of the Brush-Finch population increased to over 100 pairs by 2009. Thanks to this increase, the Pale-headed Brush-Finch was down-listed from “Critically Endangered” to “Endangered” by IUCN in 2011. This can be considered a major conservation success – it was one of sixteen bird species which Bird Life and others identified as actually saved from extinction by human intervention. (Butchart, Stattersfield and Collar – ORYX 2006). In 2011, the breeding population fell slightly below a hundred pairs, but in 2012 there was another marked increase with about 120 breeding territories occupied over a slightly larger area.