Is there Tui nesting in our gully?

There are two resident Tui in our gully. What would be good would be to know whether they are nesting. If they do nest, with the pest control we have done, there is a really good chance of the chicks being reared to maturity. The thing to look out for is to see Tui carrying twigs in their beaks and where they are building. The tree will not necessarily be a native as Tui do not know the difference. A good nesting spot is a good nesting spot to them. They are also likely to be very aggressive towards other birds, particularly Mynas. If anyone sees this behaviour please let one of our group know.