I understand that this post is very old.
But some of the things that people say about red-eared sliders are ridiculous.
Trachemys turtles may eat an occasional duckling, but they are by no means a threat to waterfowl populations.
Red-eared sliders are opportunistic, and in proportion to their abundance, it is very uncommon to see them eating mallard ducklings.
They are even less likely to prey on the ducklings of scarcer European species.
In the US, red-eared sliders are extremely abundant, but it is usually only snapping turtles that are accused of affecting waterfowl populations, and even then their tendencies are dramatized.
Red foxes, otters, stoats, grey herons, and pike are much more serious threats, but because they are American imports, it will be red-eared sliders that inevitably suffer the accusations. Videos of turtles eating ducklings followed by people saying things like "they aren't actually vegetarians" will motivate people to oppose them, because people love ducklings and can't stand to watch "evil" turtles eat them.
People are much more likely to respond to warnings that they will eat ducklings and bite and attack children (the latter accusation is almost completely false) than they are to "realistic" warnings that they might disrupt ecology, spread diseases to native reptiles, and devastate aquatic plant communities by their messy foraging activities.
Red-eared sliders also don't eat bird eggs. They cannot even forage out of water because they cannot swallow unless they are underwater.
Even invasive species don't deserve false accusations.