Ospreys are faithful to their nest site and generally pair for life. They very rarely leave a living partner but, if their mate fails to return from migration, they will often find another partner to make sure that they have the opportunity to pass their genes on to a further generation. Although, sadly, the survival rate for youngsters is poor, adult ospreys can live up to 20 or 25 years.

So, hopefully, we will see our pair at Foulshaw for a few more years.

The Foulshaw male, White YW, hatched 15 years ago at Bassenthwaite and the female, Blue 35, hatched 13 years ago at Kielder. They have been nesting at Foulshaw Moss since 2014 successfully raising 24 chicks. We are looking forward to another successful year. Egg number one was laid on 15 April: sixteen days after Blue 35 returned. Eggs two and three followed on 18 and 21 April.

Before the eggs were laid the breeding pair had to re-establish their relationship. More than likely, they will have spent the winter apart perhaps in East Africa or Europe and, as with most breeding pairs, they returned back to their nest site separately. This year Blue 35 arrived four days after her mate, which caused a bit of worry to those of us watching and waiting. However, all was well and the pair started to adjust to life together once more.

The first few days are spent getting to know each other again; preparing the nest for a new brood and warning off any intruders who may take a fancy to the nest site. The female needs to be confident that her partner can support her and the chicks. She will be reluctant to mate until the male has proved himself by providing her with plenty of fish. He will also try to impress her by bringing lots of sticks to help with nest renovation. Once the eggs are laid the female will do most of the incubating and she is dependent upon the male to feed her and the chicks and to make sure the nest is safe.

Nest renovation is not only a key part of the breeding pair’s courtship, it is an important role in preparing the nest for eggs. When the osprey family leave in the autumn, the nest is a huge flat platform just right for young fledglings to learn to fly. On the adults’ return in the spring, the nest needs to be remodelled to accommodate two or three eggs and you will see the ospreys, usually the male, enthusiastically bring sticks, bark, grass and moss to the nest to make the snug nest cup. The male osprey will keep tending the nest throughout the breeding season, adding bits to it and adjusting it to meet the needs of the growing family.

Surprisingly, even though the ospreys are quite large birds, their eggs are only about the size of large hen or duck eggs. Each egg has different markings and they can have off-white to pinkish or beige backgrounds, with random mottled dark brown or reddish splotches. Birds are quite clever in being able to influence when their eggs are going to hatch. They will often adjust the timing to correspond with good food supplies or to give the brood the best chance of survival. Like other birds of prey, ospreys can control the timing of development by staggering the laying of their eggs and choosing when to start incubation. It will be interesting to see what happens at Foulshaw Moss.

The female, Blue 35, will incubate the eggs most of the time and the male, White YW, will hunt and bring her fish. She will patiently sit deep in the nest protecting the eggs for about 37 or more days, gently turning the eggs helping them to warm evenly and to prevent the embryonic membranes from sticking to the shell.

White YW will take over incubation at times when Blue 35 is eating, having a rest or much needed exercise. Sometimes the view from the web cam looks as though the adult has left the eggs exposed but one or other of them will be close by, often sitting alongside the camera or out of view.

Any intruders, whether it’s another osprey or another threat, will alert both adults who will furiously defend the nest.