1) If you use the 'TrashStays' w/ the 'EmptyNest', they'll conflict. The nest will never get destroyed to 'seed/grow'
I modified the XPATH to exclude the 'birdNest' lootcontainer (the 'and not(@<attribute{name}>=... I didn't find that 'birdNest' had a container w/ the 'destroy_on_close='true', but shouldn't hurt if you want to CYA & put the conditional on both lines)
<configs>
<removeattribute xpath="lootcontainers/lootcontainer[@destroy_on_close='empty' and not(@name='birdNest')]/@destroy_on_close" />
<removeattribute xpath="lootcontainers/lootcontainer[@destroy_on_close='true']/@destroy_on_close" />
</configs>
2) I didn't like that the EmptyNests 'seeded' using the nest model (when scouring the landscape for nests to loot, it sucked when I came across a 'growing/seed' nest that I couldn't loot). To mitigate the confusion, I changed up the mod so the nest 'seed' was a grass model that you could find in any biome. I also gave it some HPs so you could stop the nest from re-spawning if you wanted. Just remember to change the 'GrowthRate' as needed
New to the tweaking, so excuse any problem(s) I wasn't aware of creating & thanks again for the quick & useful A21 MODs
<configs>
<append xpath="/blocks">
<block name="BirdNestGrowing">
<property name="Class" value="PlantGrowing"/>
<property name="Collide" value="melee,bullet,arrow,rocket"/>
<property name="Extends" value="treeBrownGrassDiagonal"/>
<property name="MaxDamage" value="100"/>
<property name="PlantGrowing.Next" value="cntBirdnest"/>
<property name="PlantGrowing.GrowthRate" value="270"/> <!-- In-game minutes (presumes 90-min days [3 days]) -->
<property name="SortOrder2" value="0007"/>
<property name="Texture" value="201,306,371,201,306,371"/>
</block>
</append>
<insertAfter xpath="/blocks/block[@name='cntBirdnest']/property[@name='StabilitySupport']">
<property name="DowngradeBlock" value="BirdNestGrowing"/>
</insertAfter>
</configs>