It's bug iOS 9, include in iOS 8, but in 9 version include partly.
Bug with input, with attribute readonly="readonly". Selectric use hide input:

What happen:
- If click on
selectric-wrapper start method _open.
- Method
_open set focus on hide input.selectric-input. It make selectric plugin and i don't know why. May be, more simple add listeners for keystrokes on a hidden element. And handle such events when an item has focus. Why input? If you use another element, then pressing the arrow keys, we will also scroll the document itself. Because, use input , although I could be wrong. Maybe better input for e-readers, ie, used it to enhance accessibility.
And when focus comes to input , despite the fact that it is readonly, iOS (I think so) tries to allocate space for the keyboard. I can advise a simple workaround:
$(".selectric-input[readonly]").on("focus", function(evt) {
this.blur();
});
Ie when the focus input immediately rid of him, because on iPads impossible to move through the list using the keyboard, the functionality should not be compromised.