The 28 gauge will work on pheasants.There are not many in my area but the only two I ever saw while hunting I shot with my 28 gauge.I know a couple of guys who hunt pheasant in the Valley who swear by their 28 gauge Ruger O/U shotguns using full/modified chokes and number 6 Winchester 1 ounce loads.
In the past when lead was legal I used my 28 gauge duck hunting with good results.Have a year or so ago loaded up some 28 gauge Bismuth to use on ducks.Have not had a chance to use it much in the field as I have not gone duck hunting much of late years.With extra full and improved modified chokes in my Franchi 48 AL I have good patterns out to 40 yards.
Check out the 28 Ga. Society
http://28gasociety.proboards.com
There are guys there who use their 28 gauges on geese.