Marsh harrier

Marsh Harrier
Circus aeruginosus
Linnaeus, 1758

The marsh harrier is our largest harrier and these days, our most numerous (though far from common at a few hundred breeding pairs generally). They’re bulkier than the hen harrier, lack a white rump and the females have a distinct creamy coppery head on a milk chocolate brown body. They’re primarily found in the east of the UK, over reedbeds and marshes.

I’ve dealt with the marsh harrier’s smaller, rarer, blue-grey cousin in the previous blog post, so there’s no need to repeat the mythological Greek stem of the marsh harrier’s generic name of Circus. Click here to read why all harriers are “Circus birds”.

As for the marsh harrier’s specific name, aeruginosus – this has  its roots in Latin, not Greek.

Scholars will tell you that the marsh harrier’s specific name of aeruginosus is derived from the Latin aerugo meaning copper rust and osus meaning full of (full of copper rust).

At first glance, that might seem like quite a reasonable or apt specific name for a large harrier covered in patches of copper-coloured feathers.

But copper rust is blue-green!

Think the statue of liberty if you want to know the colour of copper rust.

There are two other organisms I know of with a specific name of aeroginosus:

The bacterium Bacillus aeroginosus and the fungus Gymnophilus aeroginosus  - both exhibiting a blue-green colour.

Now there’s nothing blue-green about a marsh harrier.

Or is there?

Well…. the marsh harrier’s eggs are a very pale (indeed) blue-green colour, (more so than the more white eggs of the hen harrier), so I guess this may be why the bird has a specific name of “full of copper rust”.

The adult birds certainly are “coppery” and one could reasonably assume that 250 years ago, when these birds were classified, zoologists looked at the copper-flecked adults with their very pale blue-green eggs and thought of copper rust.

“Dulux” might have had this egg colour branded as “white with a hint of aerugo” (rather than full of “aerugo” as aeruginosus actually means), but hey ho.

The above is pure speculation and assumption – the most speculation and assumption I’ve had to make in this scientific nomenclature odyssey so far- but if you can tell me a better reason why the brown and gold marsh harrier is called the blue-green harrier then I’m all ears grapple fans…

In short,  the marsh harrier has a scientific name which means:"Copper-rust-coloured (eggs) circling hawk"