I wandered up to my alma mater yesterday, for a PCR test and spent a few hours around the lake afterwards. Disappointing to come across such a lack of diversity on there; possibly a side-effect of construction work associated with campus expansion, but I only saw eight of the twenty-four species identified on the lakeside noticeboards. Twenty-five years ago I'd have expected to see the vast majority of them if not all, and some none-residents to boot.
Yesterday's tally included greylag and canada geese, mute swans, mallards, black-headed gulls, coots and moorhens and that was it until lunchtime, when two dozen lesser snow geese flew in to graze the lawns and scrounge sandwich debris from undergrads. Missing from both the species on the noticeboards and my recollections, were herring gulls, teal, widgeon, pochard, grey herons, tufted ducks, gadwalls, goosanders, pintails, cayugas, shovellers, both northern and ruddy shelducks, barnacle geese, kingfishers and great crested grebes. There was also no sign of any black swans, but there wasn't when I was a student either, so I've not included it in my missing list.
One possible explanation is that they're over on the new lake on the new east campus, but that still looks like a very new and sterile environment.