Osprey Diary: July 2011

Last week I set off for the Highlands of Scotland to meet Roy Dennis, the founder the Highland Foundation for Wildlife. I was there to see Roy select and fit a satellite tracker to one of this year’s Scottish osprey chicks. The osprey was sponsored by the UK, US and foreign publishers of Sky Hawk. Their generous donations have made this project possible.

Roy Dennis...Britain's osprey expert

An operation organised with military precision!

Before my visit, I’d spoken with Roy on the phone to discuss fitting a satellite tracker to one of this year’s chicks. I found out that it was a complex procedure to organise and its smooth running hinged on many factors. Firstly, the chick needs to be healthy and at the right stage of growth. The optimum age is about six weeks old, a couple of weeks before it learns to fly. At this age chicks have reached their adult size ensuring a good fit for the satellite tracker. Also the nest must be accessible. Some trees are just too high and the nest base too wide to access the nest without causing damage. If the nest is on private land, then permission from the landowner is necessary. Roy has forged relationships with landowners over the years, all keen to help conservation in this spectacular part of the world. Finally…the unpredictable Scottish weather can cause havoc to the best laid plans. Too wet or windy and it becomes Mission Impossible.

Roy also explained why it’s been a particularly bad year for the ospreys. The sheer weight of heavy snowfall during the winter brought down many established nests, and returning ospreys had to put their energies into building new nests. Ospreys can carry up to half their own body weight…that’s about 1kg of sticks and nest building materials for each journey to and from the new nest site. Completed eyries measure in excess of five foot in diameter and can weigh anything up to 200kg. After all that nest building effort, it’s no wonder breeding pairs of ospreys defend their nest sites so fiercely from other intruding ospreys!

Worse still, spring gales, cold temperatures and very heavy and persistent rainfall affected the survival of eggs and chicks this year. Many eggs didn’t hatch and many chicks became cold and wet and simply couldn’t thrive. Bad weather also affects the fishing abilities of parent ospreys. If the water’s surface is ruffled, fish are less visible beneath the water. Also, the parents need more feed for themselves for energy to survive the colder weather.

Several of the nests Roy had selected for the Sky Hawk osprey didn’t produce any live chicks this year. This is simply nature in action, but it just shows how important it is to maintain conservation efforts and ensure ospreys have safe habitats to return to year after year.

A secret nest site

With everything ready to go, even the sun decided to shine down on us. I met Roy, his assistant and the tree climber at a secret rendezvous, and we set off for the nest site, bumping across miles of roads and tracks going deeper and deeper into wild forest. A fox sloped off into the undergrowth and an osprey, taking a morning bath in the puddle of a deep rut flew up past our heads, startled by our presence. I guessed few people had been this way in a long time. Where the track ended, we left the 4x4 behind and walked across several miles of springy undergrowth, a carpet of heather and wild bilberry until we reached a small clearing. A lone Scots pine held the nest up on high, and above our heads two ospreys wheeled and called out their alarm calls. Fine wisps of mist hung in the air after the night’s storm. The air was still and golden. There was a deeply magical quality about this place, as if it had been held in time.

Thistle

Nest site

Adult osprey

Getting up the tree…not as easy as it might seem!

I watched our tree climber prepare his ropes and harnesses to climb the tree. It wasn’t an easy tree to climb, made even more difficult by the wide spaced brittle side-branches and the overhanging curve of the main trunk at the top.

Negotiating the overhang

At the top and with good news

Three live chicks

Our tree climber called down the good news of three healthy chicks of about 6 weeks of age…perfect for fitting the satellite tracker. He gently lowered them down separately in a canvas bag. All the time, I couldn’t help think of parallels to the story in Sky Hawk, of this same moment, of the anticipation of seeing an osprey right up close.

Lowering the young osprey

The words I had written in Sky Hawk rang true;

“Nothing prepared me for seeing her right in front of me. It was as if the lochs and the mountains and the sky were folded deep inside her, as if she was a small piece of this vast landscape and none of it could exist without her.”

With all three chicks down from the nest, Roy identified them as two male chicks and one female chick. Female birds of prey are generally bigger than their male counterparts. It’s not certain why this is so but some theories suggest it may be that different sized parent birds may select different size prey. Female sparrowhawk can tackle bigger bird species than the male and maybe by doing so they have a wider range of prey and increase the chances of bringing more food to the nest.

The chicks stalked about, wings folded, reminiscent of grounded vultures or strange prehistoric bird forms.

Young osprey eyes are deep amber, so different from the sunflower yellow of the adult.

Their plumage is cryptic. A mottled mix of browns and whites, perfect camouflage against airbourne predators, such as goshawk.

Essential fieldwork

All the young were identified for future reference….and data taken.

They each had a metal BTO leg ring attached, each with a unique number. The BTO (British Trust for Ornithology) ring is more useful when an injured or dead bird has been recovered. The ring contains the address for the British Museum. Returning a ring can give vital information of where the bird was found, what injury it sustained etc.

Roy also fitted each bird with a highly visible numbered colour ring. This allows the bird to be recognised from a distance simply by reading the ring with binoculars, giving more valuable information if someone sights the bird and informs of it’s whereabouts. Not many birds can be satellite tracked due to expense, so being able to build up a record of colour ring sightings is very useful. The legs rings used on these three birds were blue and white; 96 (male) 97 (male) and 98 (female)

Roy weighed each bird…

…measured the length of the longest wing feather…

…and took a tail measurement…

A couple of tiny down feathers from the inside wing were taken for DNA records…

Roy also assessed each bird for body condition, if its crop was full of food, and for any distinctive weak marks along the feathers that may have indicated lack of food during a distinct growing period.

Roy spent some time deciding which osprey to choose to fit the tracker with. He’s particularly interested in the returning males…when and where do they return? Some studies show that they do return to nest sites but also explore a very wide area across Scotland, England and Wales looking for new nesting sites and undoubtedly building up a mental map. Tracking research could help establish breeding ospreys across the UK and bring back ospreys to areas where they once were a common sight. Not only is this research good for the survival of magnificent ‘flagship’ species like the osprey, but also by identifying essential habitats ospreys need for survival, we may be able to ensure the conservation of plants and other animals in ecologically sensitive areas.

Roy decided upon the biggest male to fit with the satellite tracker.

The Sky Hawk osprey

Identification;

Blue and white leg ring 97

Weight 1663g

Wing measurement 320mm

Tail measurement 128mm

Roy fitted the satellite tracker with a small harness around the bird’s back. Note the solar panel on the top of the transmitter to charge up the battery and hopefully give readings for several years.

Satellite trackers are small lightweight radio transmitters which send out signals at set times. These signals are then picked up by satellites and in turn sent to a computer that analyses the data received. Much detailed information can be gathered from this; the location of the bird down to an accuracy of 18m radius, speed and direction of flight and also altitude. This information allows a picture to be built up of the osprey’s route of migration and also flight patterns at breeding and overwintering sites. Already, sites where ospreys rest and refuel on their long migration have been identified, leading to conservation of these ecologically sensitive areas.

The harness was sewn in place with cotton. The cotton will eventually rot and allow the tracker to fall off after several years, ensuring the osprey is not encumbered by the tracker after it the battery has ceased to function.

The Sky Hawk osprey…tagged and ready to go…

Roy Dennis, the Sky Hawk osprey and me

As we sent the Sky Hawk osprey back up to the nest, I couldn’t help feeling elated but also incredibly nervous for him; for his first flight, for learning essential fishing skills, for his first extraordinary migration to Africa across some of the world’s harshest landscapes. But my mind was most filled with worries of the human threats facing ospreys…and I find myself hoping against hope; that he will not be shot or poisoned, that he will not be a victim of pollution or entanglement in human waste, that he will not be electrocuted by overhead powerlines, that he will find ‘safe’ areas to rest and fish during his long migration and that he will find enough fish despite overfishing by European trawlers along the African coastline.

Re-introduction of ospreys back into Britain continues to be a success thanks to the huge efforts of many dedicated individuals. But the migration of the osprey spans whole countries and continents. As the author of Sky Hawk I wanted the osprey to show that the conservation of our natural world cannot be brought about by individuals or countries acting in isolation. It can only be achieved through our understanding of each other; our cultural, social and economic differences, across countries and continents as far flung and widespread as the osprey itself.

The Sky Hawk osprey has been sponsored by children’s book publishers from countries as far apart as the Faroe Islands and Korea. It’s my belief that all children across the world care deeply about the future of our planet and that they should have their voices heard. Let’s just hope World Leaders, intent on the pursuit of the short term riches of power and money, will sit up and listen.