I always say the first rule of breeding birds is that you must be very patient. Your birds are showing very positive signs that they will be nesting, when they are ready. Cockatiels will breed when the weather is warmer, days are longer, food is abundant, and they have a safe place to nest. In captivity, you need to make sure you are feeding them a nutritionally balanced diet such as pellets or our foraging diets – a loose seed mix does not provide very much nutrition. You should also offer chopped veggies, fruits, multi grain bread and cooked eggs – wash the eggshell before breaking it, and then crush the shell in with the eggs and cook it together. If they do lay eggs and hatch chicks, they will eat a LOT of food and you will usually need to replenish it during the day.
Your birds also need privacy, so don’t spend too much time observing them. The female is acting like a normal bird – she is curious about the nest box but not yet ready to go inside of it. Both birds need time to get used to it and feel safe with it. One of the birds will eventually go inside the box to explore it. Inspecting it from the opening is the first step, so they are moving in the right direction. All you can do now is be patient, make sure they have plenty of nutritious foods so that they know they will have enough to feed their family, and most importantly, give them privacy so they feel safe and secure enough to raise a family.
Thank you for asking Lafeber,