Cinnamon Teal

Cinnamon Teal are seasonally monogamous, generally selecting new mates each year. Pair bonds form during late winter and early spring, with courtship most intense when multiple males gather around a single female. Nesting dates vary with elevation and latitude but are generally March to May, peaking mid-May to mid-June in Washington state.

The female selects the nest site — usually beneath dead marsh grasses less than 60 cm tall, close to water and well concealed on all sides and from above. She approaches the nest through tunnels in the surrounding vegetation, keeping the entrance hidden. The nest is a shallow depression scraped by the female, averaging 18.5 cm across with an interior cavity about 12.7 cm across by 5 cm deep, lined with rushes, saltgrass, bulrushes, grasses, and down from her own breast. If water levels rise during incubation, she augments the nest with additional material.

Clutch size is 4–16 eggs, typically 8–12, creamy white to very pale buff, sub-elliptical, and measuring approximately 4.4–5 cm long by 3.33–3.5 cm wide. Incubation is by the female alone for 21–25 days (average 23 days). Unusually for a dabbling duck, the male remains with his mate through most of the incubation period, guarding her and defending a small territory that includes the nest and his favourite resting spot.

Ducklings hatch covered in yellow down with a grey-brown eyestripe and are precocial, leaving the nest within 24 hours of hatching to travel with the female to water. They can feed themselves from day one. The male has occasionally been observed accompanying the female and her brood — a rare occurrence in ducks. If danger threatens the young, the adult female may perform a "broken-wing" distraction display to lure predators away. Fledging occurs at approximately seven weeks, and sexual maturity is reached at around one year of age.

The typical lifespan of a Cinnamon Teal in the wild is 5–10 years, though survival rates vary considerably with habitat quality, predation pressure, and hunting. The maximum recorded longevity is 12.9 years (AnAge database), with another individual recorded at 10 years and 6 months in California in 2010 (Cornell Lab of Ornithology). These figures are broadly comparable to other small dabbling ducks of similar size.

Mortality causes include predation at all life stages — eggs and ducklings are taken by American mink, raccoons, skunks, foxes, corvids, and large gulls, while adults face pressure from raptors including Peregrine Falcons and Red-tailed Hawks. Hunting accounts for a relatively modest proportion of annual mortality compared to other dabbling ducks, because Cinnamon Teal migrate early — often before hunting seasons open in their range states. Approximately 33,913 were harvested per season in the US during 2019–2022.

First-year survival is typically lower than adult survival, as is the case in most waterfowl. Ducklings that survive to fledging at approximately seven weeks face the highest-risk period of their lives during their first autumn migration. Birds that reach adulthood and establish themselves on good-quality wetlands can achieve lifespans approaching a decade. The declining population trend suggests that recruitment is not fully compensating for adult mortality across the range, particularly in areas where wetland habitat has been lost or degraded.

The Cinnamon Teal is listed as Least Concern on the IUCN Red List, but populations are declining. The global population is estimated at approximately 380,000 mature individuals (BirdLife International), with the North American breeding population estimated at 260,000–300,000 and a fall population of 500,000–600,000. Partners in Flight rates the species 13 out of 20 on the Continental Concern Score and includes it on the Yellow Watch List for declining populations. In Washington state, Breeding Bird Survey data show an annual decline of 3.3% between 1968 and 2012.

Wetland loss and degradation is the primary threat. The United States lost approximately 50% of its wetlands between the 1780s and the 1980s, with California losing more than 90% of its historic wetland area. Ongoing threats include conversion of wetlands to agriculture, intensive livestock grazing degrading upland nesting cover and wetland margins, urban and residential development, and conversion of shallow wetlands to deepwater reservoirs for recreational fishing — making them unsuitable for dabbling ducks. Water scarcity in the arid West, invasive vegetation (purple loosestrife, Phragmites), agricultural and industrial contamination, and climate change altering hydrology and snowpack all compound the pressure.

Hunting pressure is relatively low compared to other dabbling ducks because Cinnamon Teal migrate early, before most hunting seasons open. Approximately 33,913 were harvested per season in the US during 2019–2022, primarily in California, Utah, and Montana. The species is managed as a migratory game bird under the Pacific Flyway Council. Conservation actions include wetland protection, enhancement, and restoration in western states, and livestock fencing projects to protect wetland margins. The subspecies S. c. borreroi (Borrero's Cinnamon Teal) from the eastern Andes of Colombia has not been recorded since the 1950s and is likely extinct.

Five subspecies of Cinnamon Teal are recognised, spanning two continents and a remarkable range of elevations and habitats. The North American subspecies, S. c. septentrionalium, breeds across the Great Basin and Intermountain West and winters primarily in Mexico. It is the subspecies most familiar to birders in the United States and Canada.

In South America, four subspecies occupy distinct ranges. S. c. orinomus — the Andean Cinnamon Teal — is the largest of the five and breeds on the Altiplano of Peru, northern Chile, and Bolivia at elevations of 3,500–4,600 m. At these altitudes, it occupies high-altitude wetlands where few other waterfowl breed, making it one of the highest-altitude ducks in the Americas. S. c. cyanoptera (the nominate subspecies, sometimes called the Argentine Cinnamon Teal) is widespread at lower elevations — below 1,000 m — along the coast of Peru, southern Brazil, Argentina, Chile, Uruguay, and the Falkland Islands.

S. c. tropica, the Tropical Cinnamon Teal, is the smallest subspecies and is endemic to the Cauca and Magdalena Valleys of Colombia. S. c. borreroi (Borrero's Cinnamon Teal) was found in the eastern Andes of Colombia and northern Ecuador but has not been recorded since the 1950s and is considered likely extinct — a sobering reminder of how quickly a subspecies can disappear when its specialised habitat is lost.

Genetic studies have produced a counterintuitive finding: North American Cinnamon Teal (S. c. septentrionalium) are more distantly related to the South American subspecies than the South American birds are to the Blue-winged Teal (Spatula discors). This makes the species technically paraphyletic — a result that has prompted ongoing discussion about whether the North American and South American populations should be treated as separate species.

Courtship in the Cinnamon Teal is a competitive, multi-male affair. Groups of males gather around a single female and perform a sequence of ritualised displays that are specific enough to have been given formal names in the ornithological literature. These include Preen-behind-wing (the male lifts one wing and appears to preen beneath it, flashing the blue wing patch), Preen-dorsally (preening the back feathers), Belly-preen, and Preen-back-behind-wing. Males also move their heads through various positions, dip and upend as though feeding, and perform synchronous "jump flights" — all males in the group launching briefly into the air together in a coordinated burst.

The female plays an active role in mate selection. She signals interest by swimming in front of a chosen male — a behaviour called inciting — and rejects unwanted suitors by head-pumping or opening the bill toward them. Once a pair bond forms, copulation occurs on the water surface, preceded by mutual head-bobbing by both birds.

Pair bonds form during late winter and early spring and are maintained through the breeding season, though the species is seasonally monogamous and generally selects new mates each year. The male's unusually attentive behaviour continues well beyond pair formation: he guards his mate during incubation, defends a small territory around the nest, and has been observed accompanying the female and her brood after hatching — a level of paternal investment that sets the Cinnamon Teal apart from most other dabbling ducks, in which the male's involvement ends at or before the start of incubation.