I am more a Nikon user without much experience into digital SLR because of the sensor conversion factor, ie I am hoping to use full-frame digital sensor. So from a 35 mm equivalent point of view, what I found most useful multipurpose lens is my 24-120mm, then for your bird photography, it may be the expense 80-400mm VR within the Nikon line. You may wish to compare the Canon line for the equivalence. The 24mm is great for landscape, much better than 28mm but easier than the 20mm while the 120mm can double as close up nature without going into 105mm macro. There may be even better combination for the newer lens but with zooms, one must watch for optical quality by limiting the range of the zoom (my 75-300mm non-ED was not very sharp) and spending a bit more.
In Toronto, there is the convenience to see all the pro camera shop at once along Queen Street, including the Downtown Camera, Henry, Vistek, etc. Go to Digital Photography Review website to get more information.