Laguna de Sonso:

Wetland Birding in the Cauca Valley

QUICK FACTS

Location	Cauca Valley floor between Buga, Yotoco and Guacari, ~1 hr from Cali
Size & elevation	About 2,045 hectares at roughly 935 m - an ancient oxbow of the Cauca River
Protection	Nature reserve since 1978; declared a Ramsar Wetland of International Importance in 2017
Species	More than 390 bird species recorded
Star bird	Horned Screamer (Anhima cornuta) - the region's only remaining population
Facilities	Trails, an observation tower at Mata Zarza, an environmental education centre; boat trips possible
Best time	Early morning, when bird activity peaks; good year-round

Laguna de Sonso: Wetland Birding in the Cauca Valley

Most birders come to Valle del Cauca for the cloud forests — and then discover that one of the region's finest mornings happens down on the valley floor. Laguna de Sonso is the last great wetland of the Cauca Valley: an ancient oxbow lake of the Cauca River, roughly 2,045 hectares of open water, marsh and dry forest sitting at about 935 metres between the towns of Buga, Yotoco and Guacari. With more than 390 bird species recorded and a cast of waterbirds you will not find in the mountains, Laguna de Sonso birding adds a whole dimension to a Valle del Cauca trip — and it is barely an hour from Cali.

A Ramsar wetland saved by its community

Sonso has a story worth knowing. The Cauca Valley was once full of wetlands; sugarcane, cattle and industry took nearly all of them. Sonso survived, protected as a nature reserve since 1978 and — thanks to years of community action and government effort — declared a Ramsar Wetland of International Importance in 2017. That designation matters practically as well as symbolically: birdwatching is now recognised as a sustainable way to fund the lagoon's conservation and support the surrounding community. When you bird Sonso, you are directly helping keep the valley's last great marsh alive.

The star: the Horned Screamer

If Sonso has an emblem, it is the Horned Screamer (Anhima cornuta). This is a genuinely strange and wonderful bird — turkey-sized, prehistoric-looking, with a thin curved "horn" projecting from its forehead and a call that carries across the whole marsh. Sonso holds the only remaining population in the region, which makes seeing one here both a privilege and a conservation story in itself. The local environmental education centre, "Buitre de Cienaga", is even named in the screamer's honour.

What else you will see

Sonso's real appeal is the combination of habitats: open water, reedbeds and marsh on one side, dry forest and scrub on the other. That mix means a morning here can produce waterbirds, dry-forest endemics and raptors in the same walk.

Waterbirds	Dry-forest & endemics	Raptors & migrants
Horned Screamer	Grayish Piculet (endemic)	Snail Kite
Black-bellied Whistling-Duck	Apical Flycatcher (endemic)	Osprey
Purple Gallinule	Bar-crested Antshrike	Ringed & Amazon Kingfisher
Wattled Jacana, Cocoi Heron	Dwarf Cuckoo, Jet Antbird	Migrant ducks & shorebirds (Oct-Apr)
Anhinga, Neotropic Cormorant	Ruby-topaz Hummingbird	Yellow-hooded Blackbird

Two of those deserve a special mention for endemic hunters: the Grayish Piculet — our namesake, and a Colombian endemic of the Cauca Valley — and the endemic Apical Flycatcher. Both haunt the dry forest and scrub around the lagoon's edges, so a Sonso morning can quietly add two endemics to your list alongside all the waterbirds.

A field note: the sound before the sight

Sonso is a place you often hear before you see. Arrive at first light, with mist still lying over the water, and the marsh is already loud — whistling-ducks overhead, gallinules chattering in the reeds, and then, from somewhere across the lagoon, the extraordinary honking bray of a Horned Screamer. Climbing the observation tower at Mata Zarza as the sun burns off the mist, with the Western Andes rising blue behind the water and the whole marsh waking up below you, is one of those mornings guests remember long after the tanagers blur together.

Practical tips for visiting Sonso

Come early — bird activity peaks in the first hours after dawn and drops off sharply as the valley heats up, and it does get hot down here. The reserve has walking trails around the lagoon and marsh edge, an observation tower on the Mata Zarza peninsula, and an environmental education centre with basic facilities. It is also possible to explore by boat or kayak, which gives a completely different angle on the waterbirds — well worth arranging in advance. Bring sun protection, water, and footwear you do not mind getting muddy; the trails are flat but can be uneven and slippery after rain.

Combining Sonso with the rest of the valley

Sonso works beautifully as a half-day or full-day trip from Cali, and even better in combination with the surrounding dry-forest patches, which hold the same Cauca Valley endemics. Because it sits right beside Buga and Yotoco, it also pairs naturally with the Western Andes: a wetland morning followed by an afternoon climbing into cloud forest is one of the most satisfying contrasts this region offers. On our tours we build Sonso into the Cauca Valley leg for exactly that reason — it delivers a set of birds nothing else in the itinerary can.