Black-thighed Grosbeak

How to find it

Go up the slope. Around Turrialba Volcano it can be found at most spots on the volcano slope, and one local birder has not found it below roughly 1,900 m. Scan the canopy and fruiting trees at forest edges, since birds are often perched high or feeding in fruit. At Arenal, one bird perched high near the casonas in the morning. Birders on a Central Valley highlands tour saw it well along Providencia Road. Learn the song beforehand, because a singing bird on a high perch is often easier to hear than to spot.

How to recognise it

This is a large grosbeak with a very thick bill. Learn it as a short list of marks:

Male body: mostly yellow.

Face: a narrow black mask.

Back, wings, tail and thighs: black.

Wing: a white patch at the base of the flight feathers.

Bill: thick.

The black thighs give the bird its name, and the Spanish name Picogrueso Muslinegro means the same thing. Near the hanging bridges at Arenal, one visiting birder watched a bird land on a branch just below, close enough to see the black thighs. A guide who photographed one near Poás called it a hefty, beautiful bird. When you scan a high perch, look for yellow set against dark wings and back, then check the heavy bill.

Behaviour and diet

It is usually alone or in pairs. It forages high in trees for insects, and it also eats many kinds of fruit and seeds. In clearings it sometimes drops down to shrub level for fruit and seeds. It makes altitudinal movements, shifting up and down the mountains, which helps explain why it is not always in the same place. Tour groups often spot it perched high up, and a pair at Tapantí sat in a fruiting tree and gave good views before flying off.

Where it lives

It lives at the edges of humid mountain forest, in old second growth, and in pastures with scattered trees, and it is described as an uncommon resident. In Costa Rica it is resident in the highlands, especially around 2,600 m. It can go down to about 1,500 m on the Pacific side, and locally to about 1,000 m on the Caribbean side. Its range runs from Volcán Miravalles in Guanacaste south through mountain forests to western Panama. In the Greater Metropolitan Area it occurs mainly on the higher edges.

Similar birds

It looks like the Yellow Grosbeak of western Mexico and Guatemala, and the Golden-bellied Grosbeak of the Andes. Some authors once treated all three as one species, but their ranges do not overlap with this bird's. In Costa Rica, Rose-breasted Grosbeak is a migrant and Black-headed Grosbeak is a very rare vagrant, while the Black-thighed is the resident yellow grosbeak of the mountains.

Names and lore in Costa Rica

Costa Ricans know it by the nicknames Chorcho, Maizero and Chiltote. The official Spanish name is Picogrueso Vientriamarillo, and another is Picogrueso Muslinegro, which means black-thighed. Birders prize it as a song bird, and because of this people catch it and keep it in cages.

Status and conservation

The AOCR list marks it as a resident endemic (R-END), and the IUCN lists it as Least Concern.

Photography tips

Look for birds perched high in the canopy or in a fruiting tree, where they may stay for a relaxed look. A guide photographed one near Poás and Varablanca, and another posing at the Finca Dos Lados reforestation project.