Red-breasted merganser

Scientific name: Mergus serrator

How weight is recorded: Whole weight

Field notes

Appearance

Males are distinctive with glossy green heads, white neck and breast, and rusty-red underparts; females are grey-brown with a reddish-brown head and shaggy crest. Both sexes have a thin, serrated red bill adapted for gripping fish.

Size and weight

Males average 1.1–1.4 kg and 58 cm body length; females average 0.9–1.1 kg and 53 cm body length.

Habitat

Red-breasted mergansers inhabit coastal waters, large lakes, and river systems with clear access to open water. They prefer areas with minimal disturbance and adequate fish populations.

Distribution

Found across temperate and subarctic regions of the Northern Hemisphere, breeding in northern latitudes and migrating to coastal and large lake systems during winter months.

Diet

Red-breasted mergansers feed primarily on small fish including sand eels, sprats, and herrings, with occasional crustaceans and aquatic invertebrates.

Behaviour

Highly social and active during daylight hours, they are strong, agile swimmers and excellent divers. They often congregate in flocks on open water and are quick to flush when disturbed.

Hunting tips

Look for birds on open water; approach by water when possible or use terrain features to mask movement. Early morning and late afternoon activity is peak; wait for birds to drift into shooting range rather than pursuing actively. Wind direction is less critical than concealment since birds rely heavily on visual detection.

Whole weight

This species is logged by whole weight — the animal weighed entire, as taken.

Where it is hunted

Listed as huntable in 3 countries in Huntify.

Names in other languages

These field notes are general species knowledge, not legal advice. Always check the current seasons, quotas and firearm rules where you hunt.