I am very sorry to learn that Alex Cruz is gone.
I've known him in a rather odd way - for some reason he and I had the same activity times/home range so in recent years, I would very often run into him on the CU Boulder campus, and also, several times at Walden Ponds, often when nobody else was there, in late afternoons. He and I barely knew each other (I was briefly in his department quite a few years ago), but we would often chat briefly about recent birds we'd seen.
He seemed quite active - I believe the last time I spoke with him on campus may have been in Nov./Dec. when a couple of beavers had been hanging out at Ricky Weiser Wetland.
He was always friendly and ready to talk birds, even things that no doubt seemed mundane to someone of his experience, despite our rather remote connection.
There is a pile of discarded academic books that appears from time to time in the hallway of Ramaley (where the EBIO program is located) and being a bookworm I often check it. In recent months I took possession of a few of his old books, so now I realize why they were there. (I also have books from Suzi Plooster's collection -- many of you will remember her.)
I will truly miss how mysteriously I kept running into this friendly man over the years.