How sea eagles turn into cougars

THEY may be among the world’s most iconic bird species – but it seems that female sea eagles are cougars at heart.

Megan Murgatroyd, of the University of Cape Town, used data from more than 1,000 of the birds – since their reintroduction to Scotland in 1975 – to study their mating habits.

She found that female sea eagles tend to hitch up with younger mates.

The academic said: ‘In our study, no chicks were ever produced by a male eagle more than 23-years-old, while female eagles were still able to produce chicks at 26. Therefore it follows that these old females must be paired with males at least four years younger than themselves.

‘Indeed, there was an overall trend for older females to be paired on average with younger males. Cougars – that’s all I have to say.’

An example was recorded on Mull this breeding season. An 18-year-old female, known as Yellow Black Spot, had originally paired up with an older male known as White X.

RSPB Mull officer Dave Sexton said: ‘They were paired together from 2004, but in 2017 the old male, aged 22, was killed in a fight with a new younger male.’ The newcomer then became Yellow Black Spot’s mate.

The study showed that after peaking around middle age, male breeding performance rapidly declined, while female performance did not.