The surf scoter mainly feeds on benthic invertebrates.
During the breeding period, surf scoters forage in pairs or small groups on a diverse range of freshwater invertebrates.
However, the sea ducks feed on marine organisms for the rest of the year, in flocks ranging from a few individuals to several thousands birds.
Important foods include crustaceans, herring spawn, gastropods and small bivalves such as mussels.

In late winter and spring, Surf scoters tend to shift their diet according to the relative profitability of the food, showing a level of opportunism.
For example, they start feeding in seagrass beds, on epifaunal crustaceans that have increased in size over winter or on Pacific herring eggs (Clupea pallasi), during the fish spawning.

As the prey landscape changes, surf scoters will adjust their foraging effort and habitat selection.
Effort is lowest in December, due to high prey abundance, and it increases until mid-February, when prey declines.
It increases again in March, probably due to the increasing daylight time for foraging.
As the season progresses, surf scoters move to habitats with lower prey declines, instead of staying in habitats poor in prey and increasing their foraging effort.

Surf scoter usually captures its food underwater and consumes it whole.
They have been observed to select smaller bivalves than those available, probably because of the energy cost of processing shell matter.
They also seem to select slow-swimming epifaunal crustaceans.

Surf scoters consume smaller prey that are located in complex habitat such as mussel beds, which makes them use more visual cues than their congeneric white-winged scoters.
They may also visually locate siphons formed by infaunal bivalves to capture them.
Gut analysis demonstrated a strong ability to avoid ingesting vegetation while feeding on attached herring eggs.

Flocks of surf scoter appear to dive in a highly synchronous fashion and this synchrony is correlated with the group size.
 Dive duration vary with many factors such as prey type, density and profitability, season and water depth.

 Surf scoters increase their dive duration when they are feeding on herring spawning, which are harder to capture than sessile bivalves.

Adult scoters of this species dive for crustaceans and molluscs, while the ducklings live off any variety of freshwater invertebrates.
The surf scoter mainly feeds on benthic invertebrates. During the breeding period, surf scoters forage in pairs or small groups on a diverse range of freshwater invertebrates. However, the sea ducks feed on marine organisms for the rest of the year, in flocks ranging from a few individuals to several thousands birds. Important foods include crustaceans, herring spawn, gastropods and small bivalves such as mussels.
In late winter and spring, Surf scoters tend to shift their diet according to the relative profitability of the food, showing a level of opportunism. For example, they start feeding in seagrass beds, on epifaunal crustaceans that have increased in size over winter or on Pacific herring eggs (Clupea pallasi), during the fish spawning.
As the prey landscape changes, surf scoters will adjust their foraging effort and habitat selection. Effort is lowest in December, due to high prey abundance, and it increases until mid-February, when prey declines. It increases again in March, probably due to the increasing daylight time for foraging. As the season progresses, surf scoters move to habitats with lower prey declines, instead of staying in habitats poor in prey and increasing their foraging effort.
Surf scoter usually captures its food underwater and consumes it whole. They have been observed to select smaller bivalves than those available, probably because of the energy cost of processing shell matter. They also seem to select slow-swimming epifaunal crustaceans.
Surf scoters consume smaller prey that are located in complex habitat such as mussel beds, which makes them use more visual cues than their congeneric white-winged scoters. They may also visually locate siphons formed by infaunal bivalves to capture them. Gut analysis demonstrated a strong ability to avoid ingesting vegetation while feeding on attached herring eggs.
Flocks of surf scoter appear to dive in a highly synchronous fashion and this synchrony is correlated with the group size.  Dive duration vary with many factors such as prey type, density and profitability, season and water depth.
 Surf scoters increase their dive duration when they are feeding on herring spawning, which are harder to capture than sessile bivalves.
Adult scoters of this species dive for crustaceans and molluscs, while the ducklings live off any variety of freshwater invertebrates.
Surf scoter