First chick patients in hospital

Our oldest Yellow-eyed penguin chicks are now being fitted with transponders and these two were the oldest of them all. They have featured here on FB with their parents a few times: 11 August with both adults at their nest site, 18 September when the first eggs were laid; 5 November when they were the first chicks needing treatment for Diphtheria; 11 November they were alive and well. Now they are in the news again as the first chicks to be transpondered and the first chicks that needed to come into hospital: they only weighed 4.5kg and 4.8kg at 74 days when they should weigh 5.2kg. Something is not right so they both are now on a diet of salmon and are doing very well.
Since then we have caught, weighed and transpondered another 12 chicks that were 70 days old and they weighed on average 5.4kg (range 5kg - 5.8kg) - so these first two appear to be the exception - lets hope so. We have since seen both parents so it was not a loss of a parent that made them underweight and that is good news.