They are like some snowbirds - they overstay their welcome.
Cecil, I've never heard of Salmonella in wild turtles, only captive ones that have not had adequate water changes.
If the bacteria is present water changes are mute. The CDC recommends hand washing immediately after handling all reptiles included amphibians. All potentially carry salmonella.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.
