Another bit of Science Sunday for you...

The chicks are now 18, 17 and 15 days old. They are growing out of the most vulnerable stage of their lives - the first two weeks. Predation pressures are decreasing by the day and the chicks will now have some control of body thermoregulation, meaning that sudden weather events are less likely to harm them.

They have just entered the Rapid Growth Phase, a two-week period of their lives where they exponentially put on body weight and grow. 

Their adult feathers are also starting to pin through now too. They will need these for their long migration south at 12-14 weeks old before finally discarding them in their first complete feather moult starting in November and December - probably somewhere in Senegal, Gambia or Guinea-Bissau, although around 5% of ospreys overwinter in southern Europe.

We wait until this Rapid Growth Rate period has ended before ringing the birds, for obvious reasons. 

It's impossible to gender the chicks right now, but at the end of this Rapid Growth Phase females will be around 15% larger and heavier than males. If we have a mix of males and females, then it is easier to gender at the end of this growth spurt.

The birds will fledge around two weeks after we ring them. They don't increase in size much more during this time, they are almost the size of adults at five weeks old. What we'll see is continued feather growth - particularly of the flight feathers on the wings (primaries, secondaries etc). They'll obviously need these feathers at near maximum-length for optimal flight performance.

Thank you for all your name suggestions - we now have over 200 potential names to choose from. Who knew Wales had so many rivers!