Our resident female osprey NC0 has been sitting tightly on her nest after laying the third and final egg on Easter Monday. With her occasional re-shuffle or incubation change with her partner LM12, we get a closer look at her three beautiful freckled eggs.

Her first egg was the largest and the most pigmented, with the subsequent eggs paler and slightly smaller. This gives us an idea of which egg will hatch first. Interestingly, the patterning and colouration of an osprey’s eggs are similar for an individual female year on year. NC0 demonstrates this nicely when we take a look at her egg handiwork through the years.

So now begins the incubation waiting game. During this time, we will see our ospreys nestling the eggs onto their brood patches, a bare area of skin that allows them to transfer heat to the developing embryos. As osprey parents share incubation duties, (males incubate around 20% of the time), both mum and dad develop a brood patch. It’s suggested that the birds can even use this hot spot to sense the temperature of the egg!

For an even bake, ospreys will frequently turn their eggs. With a hooked beak and large talons this is a delicate process: the incubating parent will tuck their talons away and stand up on their knuckles, scooping the egg slowly with their beak. The ospreys will also shuffle the clutch around so that each egg gets its time snuggled up in the middle.

So how long do we have to wait until we see the first cheeping chick breaking free from its shelled home? On average, osprey eggs hatch after 5 weeks of incubation. Let’s take a look at NC0’s incubation stats:

So, NC0 is sitting on an average egg incubation of 36 days which would place our hatch due-date for the 10th of May. What date are you placing your bets for?

India Thomas

Species Protection Officer

The Trust’s Osprey Protection Programme at Loch of the Lowes is supported by players of People’s Postcode Lottery.