Ceulan is 90 days old today. He's still with us, rooted quite firmly, it seems, to what he knows best, the pile of sticks that has been his home for the first three months of his life. Monty is still bringing in fish for his son.

In 1995, a Spanish ecologist called Bustamante wrote a scientific paper in the BTO's Bird Study Journal on the 'post-fledging dependence period of Ospreys at Loch Garten, Scotland'. Basically, a migration age study. He looked at 35 chicks at the nest between 1968 and 1987. He found that on average, the osprey juveniles migrated 30 days after fledging. How does more recent data compare to Bustamante's research?

Here is a table of 14 Loch Garten chicks from 2004 to 2012 with their respective fledging and migration ages:

Bottom line: Recent birds tended to fledge slightly later (older) and subsequently migrate slightly later (older). How would these recent Loch Garten birds compare, however, with Welsh birds - mostly the Glaslyn ospreys from the same time period?

Comparison in fledging and migration ages between Loch Garten ospreys (n = 15) and Welsh ospreys (n = 17) from 2004 onwards

There is a real stand-out statistic here: Whilst Welsh ospreys tend to fledge the nest earlier than their Scottish counterparts (5% quicker on average), they don't half-take their time in deciding to leave. Welsh birds hang around for a further 11 days on average (13% longer). So they fledge younger, but migrate older than Scottish ospreys. Why would this be?

As we know, statistics only tell part of the story. There may be some other factors to consider:

• Not enough birds to draw a scientifically-valid conclusion (15 vs 17)
• The Glaslyn ospreys are historically extremely early breeders - does this mean offspring stay longer until a given time?
• Is migration age determined by something other than developmental maturity such as time, day length, temperature, genetics, etc.
• Do birds further south migrate later because the weather is (usually!) more temperate?
• Do Welsh birds visit the Eisteddfod for a week adding another seven days to their migration age?

As is often the case, scientific research invariably generates more questions. Ceulan is now at the average age for Scottish birds to migrate, but he's still 10 days short of the average Welsh migration age. Last year's Dyfi youngsters had an average age of 95 days for migration, which would be this coming Saturday (September 1st) for Ceulan. Time will tell.

Free food or better weather? Decisions, decisions..

Ceulan's satellite data has just come in. The surprising thing to note here, perhaps, is the lack of dispersal journeys away from the nest and Cors Dyfi Reserve. Just a handful, and the longest is still only six miles away from the nest. Ceulan fledged 37 days ago and he remains stubbornly faithful to his natal nest (remember Bustamante's research - the Loch Garten birds were gone after 30 days).

Ceulan seems to like the Dyfi - a quick six mile trip is the furthest he's been

The weather continues to be unsettled and unseasonably wet. Just last Friday, we had several thunderstorms pass through the Dyfi, taking out power lines as they did. Here's Ceulan fighting it out, just before we lost power at the project.

As I write, Ceulan has been positioned virtually in the same spot on the nest all day. He's been standing on a good-sized mullet that Monty brought back for him this morning and he's hanging onto it for dear life, calling all the time. These calls aren't food-soliciting behaviours, they are intended for Monty to tell him to stay away from his fish. It seems to have worked - both father and son are now proud owners of a mullet each.

Still nagging, despite standing on a two-pound mullet all day!

Timing will now be critical with the weather still playing tricks. Decide to go on the wrong day, with the wrong weather, and it's curtains. Ceulan has flown a grand total of 112 miles since becoming airborne five weeks ago. For the next five weeks of his life, he will somehow need to get to west Africa, 3,500 miles away - his longest journey so far has been a 12-mile round trip to the River Leri.

Ceulan now has all the anatomical and genetic tools he needs, including instructions on how to catch fish, and a map. Millions of generational data transfers from his ancestors have equipped him well. There is only one other thing he needs now, that no amount of evolutionary planning can give him: Just a little bit of luck.

No looking back...