The Black Skimmer is the only member of the family Rynchopidae known to occur in Peru. Skimmers are the only birds with distinctive uneven bills with the lower mandible longer than the upper. Their lower mandible skims or slices over the water’s surface ready to snap shut any small fish unable to dart clear. The skimmers are sometimes included within the gull family Laridae, but separated in other treatments
that consider them as a sister group of the terns. The black skimmer has an additional adaptation and is the only species of bird known to have slit-shaped pupils. Their bills fall within their field of binocular vision and enable them to carefully position their bill and capture prey. They are agile in flight and gather in large flocks along rivers and coastal sand banks. They have very short legs and small feet of limited use for walking. Photo: Black Skimmer ©Mark Vance.
LARIDAE: Gulls & Terns – Gaviotas & Gaviotines