A simple and concise suggestion regarding as the title suggests, egg laying behaviours and requirements for egg laying that goes in hand with additions like unusual egg types and cleans up some outstanding problems with nestbox laying that occasionally frustrates players, like elk-birds being compelled to sit on boxes by returning control back to modders to alter behaviour as they see fit.
[EGG_LAYING]
- Changes the behaviour of egg layers to a more flexible model where they will lay eggs wherever they currently give birth without a need to constantly cater to tending the eggs, in civilisation sites like the kobolds this would be collected within egg-pits, but comparably for animals they will just leave eggs around.
- Intelligent civilisation members without nesting behaviours will attempt to safeguard this egg by treating it as a accessory and putting it inside a object container like a bag or box in their personal holdings to keep it safe.
[NESTING] - Further defines the behaviour, in the wild eggs will be able to found in nests made of vegetation further defined by [NESTING:GROUND] [NESTING:TREES] [NESTING-BURROWS/MOUND] (that last one is subjective to the level of detail, some creatures like to build aboveground concealed mounds like crocodiles whilst others prefer to lay their eggs underground like some birds, picture attached)
- [NESTING] also defines that this creature is reliant on a nest-box to look after its young and won't give birth without a adequate place to lay their eggs unlike the default [EGG_LAYING] rework where eggs are laid anywhere when due.
[AQUATIC_EGGLAYING] - Instead of looking for a area of dry land to give birth upon, the fish (or amphibious animal) will actively choose a area of suitability in the water, large marine reptiles like the savage sea-serpent instead of nestboxing would lay loose eggs wheras inspiration for creatures like sharks can be found in 'mermaid purses' (image attached) which are permeable shark eggs without a hard shell
[SPAWN:(AMOUNT)] - The insect (or amphibian/other) creature will set down upon the ground a hive like construction called spawn filled with eggs in which the set amount of child creatures (or adults relevant to absence of child state) will emerge all at once the period of 'pregnancy' is over, a nest box all in one with unremovable eggs and similarly it can be destroyed with a path, being identical to hives.
- Unwanted infestations may continue if breeding insects like giant jumping spiders overrun a area of your fortress with multiple spawn clutches, giant toads might also brood inside your well and water supplies with a [AQUATIC_EGGLAYING] preference
- [SPAWN:(AMOUNT):VERMIN:(CREATURE)] is a additional implementation in which vermin as the child state of the creature will inhibit the built egg-hive until maturation, residual posionous vermin-children of giant spiders for instance may still bite passing dwarves like how bees sting people and pose a risk to passers by before they grow up, a more calm and friendly addition instead are tadpoles in pools courtesy of frogs & toads.
With these summary additions i hope that some frustrations might be relieved, and more advanced gameplay that doesn't exclude egg laying races can be achieved.