THE ANIMAL FILES

Common loon

Gavia immer

Excellent underwater propulsion comes with an awkward walk ashore.

The common loon pursues fish beneath the surface using large webbed feet. Its legs sit far back on the body, a useful arrangement for swimming but an awkward one for supporting a walk on land.[1]

Follow the evidence ↓
Common loon
Image: John Picken from Chicago, USA · Commons · CC BY 2.0
Propulsion
Large webbed feet and strong legs[1]
Hunting
Visual underwater pursuit[1]
Moult
Flight feathers are shed together[1]

Power behind the body

Rear-set legs drive the body through water and help manoeuvre during pursuit. On land the bird may push itself forward while its belly stays low. Taking flight from water also needs a running start.[1]

The fish is tracked by sight

The loon spots fish and chases them underwater. Clear water matters because visibility affects that search. Many prey are swallowed below the surface, while larger catches may be brought up first.[1]

Calls and feathers change the timetable

Wails help birds maintain contact, while a male yodel serves territorial communication. Adults also undergo a period of simultaneous flight-feather replacement, temporarily losing flight even though they remain aquatic birds.[1]

A COMMON MIX-UP

Does clumsy walking imply poor movement overall?

No. The leg arrangement that is awkward on land supports powerful swimming and underwater pursuit.[1]

TRY A LITTLE REASONING

Why could murky water affect a fish-eating loon?

Reveal the explanation

It relies on seeing prey underwater. Reduced visibility can interfere with finding and following fish.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Common loon (fixed revision; adapted and translated)
  2. NCBI Taxonomy — Gavia immer (identity and classification)

Last fact check:

One discovery leads to another

Emperor penguinThe egg has no nest. Dad brings the warm floor.Aptenodytes forsteri ↗Great white pelicanA pouch takes in the water, then lets the water go.Pelecanus onocrotalus ↗Blue-footed boobyBlue feet are part of the courtship display.Sula nebouxii ↗