Yesterday I had discovered three chicks and one unhatched egg in the nest. When I checked again today there were 4 chicks. This confirmed a few important facts. Incubation had been 17 days. Finding just 3 chicks in the nest yesterday and a 4th today could mean only one thing. Incubation had begun after 3 eggs were laid and before the clutch was complete. One of the things that I wanted to acheive by watching and studyng this pair of Dippers in the intense way that I have , was to establish my own facts rather than rely on other peoples research and information which is often recycled, 3rd hand information rather than anything based on private study. All previous information that I have read, told me that incubation would not start until the clutch was complete, in other words, after the 4th egg. This is to ensure that all the chicks hatch on the same day and have an equal chance of survival, However, this clearly is not the case and 3 chicks will have a head start on their younger sibling. In times of food shortage, the younger chick in the nest would certainly perish but in a season when food is plentiful this is not an issue. The male bird is already proving to be a brilliant father. I watched him for an hour tonight, he was working almost tirelessly catching prey undrwater and then delivering it to the chicks. At one point I counted to 30 before he emerged again, but mostly he would spend just a second or two delivering his morsel. he seems quite happy to catch food from around the nest so this will give me some great opportunities to watch him feeding as well.