Pretty sure all of us wildlife watchers have these, that one species (or species) that always seems to vanish right before we get there or decides to not show itself. Despite our best efforts we just can't find them. My main one is Greater Roadrunner... heard them twice, gone chasing reports soon after posting, spent considerable time trying to spot one... but still empty-handed on actually seeing a wild roadrunner. I also have a track record of missing Wilson's Phalarope, but have yet to visit their main breeding and passage sites. Red Fox is the only mammal I could consider a nemesis... all my foxes so far have been Gray, despite reports of Red Foxes in my area and places I visit. What are your nemesis species?