Wow, they survived the 80s freezes but were killed in 2009-10 !
I think age was a big factor also. I don't know what the ultimate age of royals are, but I would think that after 100 years they won't be as quick to grow back leaves or as good at bringing nutrients up the trunk to replenish a lost crown.
I know the royals you are talking about. My grandparents used to live right across the bridge in Tierra Verde, and I've been there twice, once when I was a young kid. I specifically remembered the palms and had my grandpa take me back in fall 2010. Most of the big royals along that avenue were being killed by woodpeckers, there were several active woodpecker holes all over them.maybe this is what killed them? I also saw all the naturalized royal seedling you mentioned, so I take it back, that is the farthest north I've seen royals naturalizing!
Interestingly, the largest gumbo limbo I've ever seen is around there somewhere too, it's the size of a huge old live oak with similar spreading branches
Well I saw the damage that the winters did to the palms and them dying right afterwards, so maybe the ones that died couldn't recover from the cold because of the woodpecker damage. There still are I think 4 big ones left though. There are at least 20 that I've counted naturalizing. I've seen them as small as strap leaf seedlings to the ones with 6-8 feet of trunk. There are probably quite a bit more than 20 though, because all the ones I have seen are next to the trails.
I know the gumbo limbo you're talking about. It's at the Desoto national memorial right across the Manatee river in Bradenton. It's actually a state champion in it's spread.