Saturday, 31 October 2015

An Osprey For All Seasons – Blue 7H

30th October 2015

Bad luck! If I’d any good luck to spare he could have some. I wish we could all have good luck, all the time! I wish we had wings!” [Robert Bolt: A Man For all Seasons, II,i.]

We call it the “activity counter” - and in the world of GPS-based wildlife tracking, it can be a dreadful, portentous, doom-laden thing.
The activity counter is a column of numbers in a data file. When a bird or animal is being tracked, sensors in the PTT unit record any movements between sample points, and increment this number at each occurrence. An activity count that has NOT updated within a significant span of time, brings on a feeling that is all too-familiar to wildlife researchers:-

Oh, no – not again...” 

Whether tracked or not, the population survival statistics for sub-adult overwintering ospreys are – as with the young of many other predator species – brutal and uncompromising. Fewer than one in four ever return to their natal regions in northern Europe to breed. It's unclear if this ratio is getting worse, but it certainly isn't getting any better. Many adverse factors seem to be at work, and the renowned conservationist Roy Dennis has estimated that some 60% of losses are due to “human activities” - either directly (illegal shooting and trapping, vehicle collisions, wire strikes, and so on) or indirectly, through loss and conversion of habitat and potential nest sites. Ospreys and other raptors that survive to breeding maturity have one thing in common: 

They all had good luck, ALL of the time.

7H was fledged at Kielder in 2014.  She became special to us in the way that these things always happen: though interest and familiarity. But 7H was not a pet - she was and remained a wild, free creature, doing exactly what her nature had inclined her to do. In following her adventures and those of her kin from Kielder Forest, we were able to learn more about this nature – and at a level of detail that may not have been achieved before.

We observed her migration with bated breath, over land and sea. We watched as she caught rides on passing ships (occasionally in the wrong direction.) We saw her learn to catch fish, and how she became gradually more proficient at this.

7H was part of my study into osprey flight strategies, proving that even very young birds of this species have an innate ability to exploit the winds and thermal air currents, and to cover vast distances with the minimum expenditure of energy. She contributed to new understanding of how first-winter ospreys settle into a feeding territory, and interact with others of their kind. She even taught us how fast she could fly, and how far... 

On her initial migration from Northumberland to Morocco, 7H traversed 5188 km. This might sound like a whole lot of flying to us, but her activity in the year AFTER arrival puts this in a startlingly different perceptive:
In the ensuing twelve months, 7H's total distance flown was an additional 9500 km – all carried out within about 40km of her “home” roost locations. Clearly, our traditional view that wintering ospreys “are mostly sedentary” does not reflect how active they are on a day-to-day basis.

 Because we were “with” 7H through the full cycle of seasons, we are able to see how those seasonal changes affected her foraging behaviour. We had confirmation that ospreys will seek for, and use, different hunting areas – even when there are more than adequate supplies in just one of those areas. And in particular, a detailed analysis of 7H's favoured perches and roost sites revealed that – to an osprey – seclusion and the absence of human disturbance are much more important than scenic views or epic landscapes.

So, yes – we have learned a great deal from Blue 7H and this knowledge is important for future conservation efforts. But 7H herself would not have cared one jot for that. Instead, she spent 399 days in Africa living the life that she was born into, free and wild. For those 399 days it had appeared that she was doing everything right: she had chosen a country where wildlife protection law is regarded more seriously than it is in some less-civilized parts of the world – such as Ireland, or Scotland.

Personally, I choose not to grieve for the passing of 7H, but just to be thankful for these many insights into her unique way of life. It has been a rare privilege and one that I will not forget any time soon.



Joanna has written a valedictory article about 7H on the Kielder Ospreys blog, HERE
Data provided courtesy of Forestry Commission England