Excessive mod spawn without sufficient despawn causes performance degradation in large multiplayer servers, this mod attempts to negate that by specificially targeting the biggest contributers.
The first version merely increases despawns but future addittions may include changes to AI that reduce the impact from pathfinding.
Currently includes patches for medieval expansion's Aurochs which have a much broader spawn allowance than most other animals in vanilla.
Version 0.1 changes:
Reduced player distance for despaw  to 0 for butterflies.
Reduced player distance for despawn to 1 for hares and hyenas. Also removed the requirement for darkness for both.
Reduced player distance for despawn to 1 for Aurochs (medieval expansion) but left light requiremets as these animals are desired for farming.
Increased minimum spawn temperature for Aurochs to 0 to somewhat lower their appearence in general.

Patch only impacts server despawn behaviour.

Note: currently untested.