Firstly; I thought I'd describe my aviary as this may have some bearing on the behaviour of my DB's. My aviary consists of a main area (3 X 3 metres, mostly roofed) and then a long 12 metre by two metres extension. About half way down this flight, I have roofed a three metre area including a sheet of metal decking on the side. I've placed a number of branches of tea tree between wicker nesting baskets at that spot.
The initial stages of nesting and laying eggs was very subtle and I only glimpsed the hen moving in and out of a wicker nesting basket occasionally, usually with the cock bird nearby (nesting basket located about half way down flight as described above). I though the hen may have been building a nest but as I did not see her at or in the nest very often, I wasn't sure. The two spent most of their time at the end of the aviary where it is very sunny so I didn't think they were overly serious about nesting.
This went on for about three weeks and I didn't for one minute think that the hen had laid eggs until one day when I was in the backyard doing some work (painting) when I noticed the sound of baby birds. At first I thought it may have been the silvereyes or superb fairy wrens but noticed the noise was coming from the aviary. Every time I looked over, the DB pair were in their usual spot at the end of the aviary sunning themselves.
Curious, I sat very quietly for awhile to try to see where the noise was coming from. After about 10 minutes, the DB's came out of their sunning spot and the hen entered the nest where she was met by a hail of baby cries. very exciting for me as these are the first finches I've ever bred!

Anyway, of interest, was the behaviour of the two around the nest and this has taken about a week of sitting quietly and watching to be able to put into wordsr. Firstly, they do not spend a lot of time in the nest but rather, fly back periodically. The male will stop at a spot on a branch about 60 centimetres below the nest and assess whether things are 'safe'. He then calls out to the hen and she will go through a routine where she lands on a branch; stops and then flies to a branch on the other side of the nest, where she stops again before flying up to a branch next to the nest. She stops here as if performing a last safety check before entering the nest. Upon entering the nest she is met by the usual hail of babies cries (I assume she is feeding). She never stays in the nest for very long before flying back to her sunning spot or to the feeding station.
During this period, the cock appears to be the lookout. I believe he is the lookout because any other DB that flies past, he engages in a pursuit around the aviary. He seems to pursue until he is satisfied that there is no threat and then returns to his 'guard' post. I have not seen the hen leave the nest whilst this is occurring apart from one occasion where his pursuit ended in the sunning spot and he called for the hen (she came out of the nest and flew to him).
I have been surprised by the new arrivals and I will post photo's when they come out of the nest but I must say, I never thought for a moment that the DB's had laid eggs due to the periodic nature of the nest visits. I have noticed that the hen does go into the nest at nights and is accompanied by the cock birds most of the time - the other times he perches on a branch immediately outside the nest. To be honest, I don't even understand how the hen and the cock incubated the eggs as they always seemed to be in the 'sunning' spot.
Anyway, they have been my observations and very excited about the new arrivals. Interesting little birds to say the least!
