Jen and Crysta8 hours, 24 minutes ago
It is every multiple of 5 of an adult bird that will contribute to a nest, except Cuckoo which won't build any nest. It cannot contribute to a nest if it has already built part of the nest that is incomplete or needing repair.
Also, this is the info listed in the green side infomation panel under Chicks in the Wildlife Guide.
"Baby Chicks
The Fairies and Elves of Fairyland play an important role in helping the Fairyland birds to lay their eggs and produce baby chicks!
Here's how it's done:
Important Fairyland fact: Birds will only nest and lay eggs in a nest which they have helped to build. So for example, a wren will only nest and lay an egg in a nest which another wren helped to build.
First, you'll need a completed nest in your Garden (nesting trees are available in the gift shoppe.)
Decide which chick you'd like to try for first, and attract the adult bird to your Garden while the completed nest is sitting there empty. Every 10th of that bird spotted in your Garden will nest in your empty nest (remember, the nest must have been part-built by that same type of bird!)
When it's nesting in your Garden, the bird will have a task for you to complete before it will lay an egg (speak to the bird to ask it about the task - different birds will have different tasks for you.)
As soon as you complete the task, the bird will lay its egg, and you will then need to leave the correct food out for the chick (low feeding table) and it will soon hatch and the chick can be spotted.
Finally, watch out for Cuckoos! They are attracted to, and will nest in, any empty nest! You can either deter them (with Butterpillaflora flowers) or shoo them away if an unwanted one decides to nest in your Garden.
Good luck, and have lots of fun with this challenge!"