by Pajarita » Thu Oct 02, 2014 9:59 am
I don't think that either twilight actually turns them on or off, I think that their endocrine system 'measures' the number of hours that there is light and, when it gets to a certain number of hours, it sends the signals to start producing sexual hormones and, when it's down to another certain number, it sends the signal to turn them off. The point when they start producing them is called the point of refractoriness and we know that, for canaries, it's 13 hours and that they breed best at 14 hours of light but I've never found any studies on any species of parrots.
And yes, it is as Wolf explained, they need to be exposed to both dawn and dusk but you don't really need to get up and uncover them before dawn. I have friends that turn off the artificial lights and wait for night to fall and the birds to be asleep before they cover them but they uncover them before they go to bed (in the dark, of course) so, in the morning, they are exposed to dawn and they don't have to get up that early. But, in reality, this is only a problem during the summer when there is already a bit of light at 5 am because, in the winter, dawn is much later.