Section concerning ducks
A duck is an animal. The description of duck is "A colurful male duck, with his bill held proudly high.". The duck is undescribed.
A reed nest is a home. The description of the reed nest is "A bunch of reeds artfully woven together. [if occupied] It's occupied by a pair of ducks.". The printed name of the reed nest is "[if occupied]duck nest[else]nest of reeds". Understand "reeds" and "duck nest" as reed nest. The reed nest is undescribed.
Instead of taking the reed nest:
say "The nest looks fine where it is.".
Understand "weave [the reed stems]" as transforming.
Instead of transforming the reed stems:
say "You weave the reeds into a nest-like shape. You place it gently by the pond.";
now the reed stems are nowhere;
now the reed nest is in the location;
now the reed nest is suitable.
Every turn when the reed nest is suitable for the third turn and the reed nest is empty:
say "A brightly coloured duck wades to the nest and finds it acceptable.";
now the duck is in the location;
acquire duck;
now the reed nest is occupied.