Anne-Marie of Pondering Pikaia has posted a fine piece on the shrew's dilemma -- death in a beer bottle. It would be hard to design a simpler and more perfect death trap for small mammals, and shrews seem to be more vulnerable than mice.
Maybe it's the resonating effect of the bottle when a trapped beetle is scratching inside. Maybe it's the tantalizing bouquet of beer-stewed invertebrates. . . . whatever it is, it works.
Of course, its not just beer bottles that attract shrews, coke bottles work too. But like shrews, mammalogists are strongly attracted to beer bottles -- as long as there is beer or shrews inside.
Pondering Pikaia -- check it out.