Yet another Manx shearwater post I'm afraid, but it won't be long before the last few are on their way to Argentina. This video shows the last of our nest box birds. He or she can be seen venturing to the entrance of the tunnel for a peek of the outside world for the first time. He/she then takes the plunge and leaves the sanctuary of their burrow for first time following 60 days cooped up in safety. Vigorous wing exercising follows. This was filmed on 24/9 with the chick weighing around 600g. By yesterday they were down to 545g at 64 days - the average fledging period is 70 days so they will be on their way any night soon
This is nest box 15. One of the parent birds (the male) has bred in this box since 2015. We installed the boxes in 2014 and he instantly paired up that year before breeding for what was probably the first time in 2015. Each year he and the same female reared a chick successfully and, as they gained more experience, laid their egg earlier and got their chick away earlier too. This year only the male returned however, the female either hadn't survived her winter trip to Argentina or had opted for a new burrow and partner. The new female was unringed so we knew nothing of her history. This new partnership meant they were late laying, hence their offspring being the last to fledge.
Adults weight around 400-420g, they feed their chicks up to a much heavier weight thus allowing them extra reserves for their debut flights to Argentina, alone and inexperienced at finding food for themselves. The heavier the better, although too heavy and they won't fly as efficiently. Its a real balancing act. This one topped the scales last month at the heaviest weight we have recorded for any of our chicks 'peak weights' - 740g! At this stage, now 545g and no longer being visited by the adults, the fledgling appears to be losing around 10g a day so by day 70 they should be around 490-495g - a very good weight indeed (we consider a 'good weight' to be anything above 440g at fledging). We will keep an eye on the camera and hopefully catch the moment of departure
In the meantime enjoy the first time the chick ever sees the outside world.....(click on 'expand' to see the video at full screen)