When we last heard from our Live Interpretation volunteer Mark Baldwin, his love for our resident marsh harriers was evident. This month Mark informs us on the interesting history of our marsh harriers, from which I learnt a great deal and hope you will too...
Marsh harriers are the majestic and regal raptors that rule at the top of the food chain. They have evolved to adapt to this harsh environment, with dense cover which hides prey and in this water based, isolated environment.
Here I will list the many key features that have made this wetland specialist so successful.
There are seven sub species of the marsh harrier worldwide. These evolved from a common ancestor of the Montagu's harrier approximately three million years ago. In Europe, they populated various countries from the UK to Australasia. The oldest of these being the African marsh harrier. Other species are the Eastern marsh harrier, the Australian swamp harrier, a large and heavy bird, the Malagasy, the Papauan, the re'union, which is very rare and settled on a small French island off the coast of Madagascar, and of course the Western marsh harrier.
A male marsh harrier by Mike Malpass.
Our British species the Western marsh harrier is the youngest of the marsh harrier group. It is also the most evolved of the species. This harrier has many key features that have enabled it to survive and thrive at the top of the food chain.
The eyesight of the harrier has the ability to see from high in the air and when quartering low over the reed beds, penetrating deep into the reeds seeking prey. To compete with crows and other raptors, the hooked bill is larger and stronger than the other British harriers, enabling it to feed efficiently at a carcass.
The face of the harrier is round and surrounded by a facial ruff of feathers that can be used like a puffed up tunnel to pick up and direct any sound to the harrier's large ears. They are able in this way to pinpoint prey effectively.
"What are you looking at?" An inquisitive young marsh harrier by David Mower.
The long wings of the bird assist their hunting style. They are able to quarter the reed beds, soar, and skydance without the need for warm air thermals as other birds require.
All harriers have long legs however, the marsh harrier has evolved to have the longest legs and the largest talons enabling it to surprise and reach deep into the reeds for unsuspecting prey. The large talons are the weapons that allow the prey to be dispatched quickly, and also heavier prey can be taken, unlike with the Montagu's harrier and the hen harrier, who do not have this ability.The size and skill of this bird enable it to take larger prey and be an effective predator of the wetlands.The male bird passes food to the female or juvenile, in an aerial transfer of prey during the breeding season. This action ensures that food is not lost and the location of the nest is not exposed.This action is known as the food pass.
The food pass in action by Ben Hall (rspb-images.com).
The plumage of the marsh harrier has evolved to effectively break up their outline. This makes them hard to see. The male hunts on the salt marshes and through the reed and in a more open landscape. He is therefore a different colour to the female, he is tri-coloured and has a combination of a light coloured head, blue grey wings and tail, black wing tips and a rusty coloured belly. The female is the reed bed specialist as she is largely a brown bird with cream crown and cream shoulders. The juvenile is a much darker brown bird usually with a cream crown.
In conclusion, with all the skills and abilities the marsh harrier has evolved, it leaves it unchallenged for its title as Lord of the Reeds.
Speak soon,
Mark Baldwin.