God, why did I have to see this thread on a holiday weekend....
Clyde has no credits I can find on any Glen Campbell album from 1970 to 1988.
With insomnia in full tilt, i dove into guest logs for the Tonight Show, since he referenced being on the Show with Robert Blake and his bird Fred (named La-La in real life, by the way, and not owned by Blake).
Robert Blake was in the frequent/regular guest rotation on The Tonight Show with Johnny Carson from 1972-82. Besides the Barreta fame of the day, I can attribute this to him having been a known commodity as a child actor on the My Gang/ Little Rascals shorts, and to obviously being an entertaining guest. His highest number of appearances was 12 in 1974. The show Barreta ran from 1975-79, so I have to think an appearance with the bird would have occurred during this timeframe.
The logs show musical guests. Clyde is nowhere to be seen. He is also listed nowhere as a session musician in Doc Severinson's orchestra, or subsequent iterations after Carson's departure.
It appears you encountered a nice gentleman telling tall tales. Sorry.
Now, goodnight. Pretty sure I'll be able to sleep tonight.