var imageFiles_co_4 = new Array();
imageFiles_co_4['0'] = new Array ('_images/co_Bird.gif', '_images/co_BirdMouseover.gif');

function image_on_co_4 (position) {
   var doc = eval("document.imageco_4" + position);
   doc.src = imageFiles_co_4[position][1];
}

function image_off_co_4 (position) {
   var doc = eval("document.imageco_4" + position);
   doc.src = imageFiles_co_4[position][0];
}