why white eyes?

Subject: why white eyes?
From: "Wim Vader" <>
Date: Wed, 25 Mar 1998 13:24:26 +0100
                        WHY WHITE EYES?
        One of the things that struck me in Australia, was that so many birds,
particularly passerines, had white or pale yellow eyes! Without having
collected hard and fast data, I am quite sure that the percentage of
white-eyed passerines is considerably higher in the Australian fauna than
e.g. in Europe.
        Can someone help me with a plausible explanation for this phenomenon? It
concerns species in widely different families, from scrubwrens and
thornbirds to crows, currawongs, chats and peewees, so the change must have
occurred many times during evolution.
        I have thought of some kind of "anti-glare", but if you look through the
fieldguide, it is far from always the birds from the open steppes that have
the white eyes (e.g. Grey-crowned babbler, new Holland honeyeater,
currawongs). So what can it be? Just "the luck of the draw", or what?
(Similarly, I found crests to be "uncommonly common" among the birds in the
Himalaya foothills in India).
        Heavy snowfall outside today in Tromsø, N.Norway (70*N), but the first
Oystercatchers Haematopus ostralegus, Starlings , and White Wagtails
Motacilla alba have been observed, the first harbingers of the spring that
is still slow to arrive (And won`t be here until in 6 weeks or so).

                                        Wim Vader, Tromsø Museum
                                        9037 Tromsø, Norway

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