I'm about to kick off a game of Dungeons and Dragons. My setting is magic-medieval and the plot is that the power of flight has been suppressed by an avenging god. How long would it take before the lack of flight in the animal population would have visible effects on the ecosystem as a whole? IE, how long do my players have to reverse the effects, and what signs might they see that show how badly the world around them is falling apart?
Narrowing it down a little;
The reason for the lack of flight is simply "magic". I picture it a bit like all creatures suddenly "forget" how to fly - ie birds will still have wings, they just can't get off the ground. I can be more specific here if it's required, but as of this moment I haven't defined it beyond that.
All creatures with flight are affected at the same time, and the change is quite abrupt. I expect a small subsection of each flighted population will simply die from fall impact.
Assume the area affected is several hundred miles across, centered around the city the players are in. Any new creature entering the sphere of effect loses flight instantly. Anything leaving it gains it back.
The technology is roughly a medieval level, but with magic. Magical flight methods are also neutered (including magical beasts).
This will take effect in a late spring to early summer range.
I'm currently working on the assumption that it would be about a week, maybe two at a stretch, before the lack of flight started showing significant effects to the animal and people populations as a whole. Obviously long-term we'd be talking crop failures from lack of pollination and ecosystem imbalances, but exactly how much can go wrong in just a few weeks?