Incubation at Site B

Having raised three chicks at Site B last year, we are hopeful that 03 and his mate will be similarly successful this summer. On Saturday evening last weekend the female began sitting low in the nest for the first time; a sure sign that she had laid the first egg. They have been incubating solidly since then with little to disturb them. However on Easter Saturday morning, a worrying development occurred. Richard Jagger and Carol Pilson, who were on duty at 6am, take up the story…

“03 lazily floated in from the east. I, Carol, and the unringed female turned our heads to watch. It was an early return from his first fishing foray of the day. He gradually picked up speed and . . . did he just dive-bomb the female? This wasn’t 03. She mantled her wings and took to the air. He circled to return. An intruder. 09(98)?

She followed after him and they spun low round the nest before straightening out and disappearing  over the trees behind our heads. But, was the unringed female in the lead? And the eggs were alone in the nest, unsheltered and unguarded. Nervous smiles passed between us. From the minute they are laid to the minute they hatch osprey eggs are rarely left alone day or night. Whole four hour shifts can pass without the female stirring from her prone position warming the eggs and protecting them from danger, or perhaps a quick changeover between male and female when he brings her back a fish.

The seconds turned into minutes and mounted up uncomfortably. Still she had not returned. Still the eggs were uncovered. Then in the distance – an osprey. At last she had returned, we hoped . But, no, it wasn’t her. A fish carried in that characteristic Osprey way was clasped in his talons. 03, it had to be. At least he would take up the incubation when he realised what was wrong. 03 sauntered in, approached the nest and – passed right on by, alighting in a nearby tree and proceeded to eat the head of the trout with his back to the nest. Had he even noticed the female was not there? He had passed literally within a few feet on the nest.

This was getting too much to bear. Ten long minutes passed before he bothered to return to the nest with the rest of the fish, seemingly to pass to his mate, for when he landed on the side of the nest he seemed to stare in confusion, looking one way then the other, then down at the eggs, then repeat, until finally it was all too much and he simply tucked into the rest of the trout, still leaving the eggs un-incubated. All had not gone unnoticed by a watching magpie who boldly landed on the other side of the nest to only muted protests by the much bigger Osprey.

Our hearts were in our mouths and our eyes glued to our binoculars until our arms ached as the magpie repeatedly plunged its beak down into the nest, tossing nesting material into the air, hoping an egg would not appear in its mouth, until finally 03 exerted enough threat to see the magpie off. At least now he would sit on the eggs. Well, after a few more mouthfuls of fish that is. And when he finally hunkered down the eggs had been uncovered for 42 minutes. And we can only hope they haven’t chilled in this time and no permanent damage has occurred. The fact it was a relatively warm sunny morning should swing things in their favour, but a little nervousness will reside within us until that first little head peeps above the nest rim.

And as for the female, she finally returned an hour and a half after she had left, taking over the incubation as if nothing had happened. And as we left our shift all seemed well, and calm. The call of cuckoos in the woods a faint reminder that not all eggs out there would come to hatch. Thank goodness the cuckoo doesn’t parasite Ospreys! The eggs today would have stood no chance.”

Female incubating

We hoped that 09’s intrusion would be a one-off, but worryingly the same thing happened when 03 went fishing this morning. Once again the female chased the rival male off, but in doing so she left the eggsunattended for 45 minutes. At this early stage this should not result in the eggs failing, but if 09 continues to cause trouble then there is no guarantee that the eggs will hatch. All we can do is keep our fingers crossed that his intrusions become less aggressive…