Ring-necked Duck

How to find it

Start with open, deep freshwater: lakes, ponds, marshes and reservoirs, especially in Guanacaste. Look carefully through flocks of other ducks. On one Costa Rica tour a handful were mixed with many Blue-winged Teal and a few Lesser Scaup at Cachi Reservoir. Check the bill first for the white ring, then the peaked head. Expect small numbers, since another tour found a single bird on the Angostura reservoir. Water levels shift where the birds sit, so conditions matter.

How to recognise it

Start with the white ring on the bill. The chestnut neck ring that gives the bird its name is rarely visible in the field, so do not wait for it.

Males have black backs. Male scaup have pale gray backs and no white ring on the bill.

Females show a white eye-ring. Female scaup lack one.

The head is peaked and angular, while scaup have rounder heads.

In flight it shows a gray wing stripe only on the inner wing, where scaup show a longer white stripe.

On the water it floats lower than dabbling ducks, as is typical of the Aythya diving ducks.

What it sounds like

Recording: Norma Malinowski, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

This is a diving duck. It goes under to feed on water plants, insects and mollusks, and it usually forms flocks.

It handles shallower water than Lesser Scaup and stays well into the dry season.

As a Nearctic migrant it makes strong seasonal movements that follow changes in water level in its habitat, so a pond that holds ducks one month may be empty the next.

Where it lives

It likes open, deep freshwater marshes, ponds and lakes. In Costa Rica it is an uncommon to common winter resident in some places, mostly in Guanacaste, especially the Tempisque basin.

It is rare and local on the Caribbean slope and in the Central Valley. Records also come from ornamental ponds, including a hotel pond in La Fortuna in the Arenal area, and a single female was found at Coris de Cartago in November 2016.

When to see it

Birds arrive in late October or November and stay through January, sometimes to March, depending on water levels. Another account gives their presence as October or November to May or June.

Similar birds

Scaup are the main look-alikes, and Lesser Scaup share the same waters in Costa Rica. Check the back colour in males, the eye-ring in females, the head shape and the wing stripe in flight. A white ring on the bill separates this duck from scaup.

Names and lore in Costa Rica

Costa Rican lists give Porrón Collarejo and Porrón Acollarado. Other Spanish names include Pato pico anillado and Pato acollarado, and the Nahuatl name Texōloctli is also recorded.

Status and conservation

The official AOCR list marks it M, a migrant, and the national museum's catalogue of birds of the Greater Metropolitan Area also lists it as migratory.