Thought I'd add what Dr. Bill kindly sent me about taking a gander--I had wondered fleetingly about it as I posted but was too lazy to LIU (thanks, Bill); from Quinion:
A quick, er, gander at the word’s history is illuminating. It seems the verb to gander in this sense is actually American in origin, something I find more than a little surprising, because it sounds English to me. A little more delving, however, shows that the roots of the expression are indeed from this side of the pond. A work of 1887, The Folk-Speech of South Cheshire, says, “Gonder, to stretch the neck like a gander, to stand at gaze”. The next known example is from the Cincinnati Enquirer of 9 May 1903: “Gander, to stretch or rubber your neck”. It is claimed that it comes from thieves’ slang.
There’s your source. Think of a gaggle of farmyard geese, wandering about in their typically aimless and stupid way, poking their noses in everywhere and twisting their necks to stare at anything that might be interesting. Geese are the archetypal rubberneckers. No doubt to gander became the term because to goose had already been borrowed; this was taken from the way that the birds were known to put their beaks embarrassingly—and sometimes painfully—into one’s more private places.
The form you quote, to take a gander, is recorded from the USA around 1914; here, gander is a noun in the sense of a inquisitive look. In the century since, that form has become much more common while the verb has lost ground.

http://www.worldwidewords.org/qa/qa-gan2.htm