By Bunmi Adigun @bunmi_adigun

THESE grouse bring a whole new meaning to the term ‘angry birds’ as they launch into a mid-air battle

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Two male black grouse square up to do battle

While spring is usually considered a time of peace and tranquility, these male grouse clearly didn’t get the memo.

Photographer Markus Varesvuo has been studying the behaviour of birds for 40 years

Taken by Finnish photographer Markus Varesvuo, the powerful images show male black grouses in Vaala, central Finland, fighting it out for the right to mate.

The male grouse come together in a lek to fight each other and show their strength to female grouse

Every spring male grouse congregate in what is called a ‘lek' to engage in a show of strength by fighting and posturing in the hopes of catching the eye of female grouse.

Female grouse are also known to fight each other to be the first to mate with the males

This period is critical for the species - as it happens during the breeding season, it also acts as a natural way of the females to find a mate with the strongest genes.

The male grouse claim a small patch of an open field and defend it against any intruders

Markus said: “In spring the males get together every morning for weeks to determine who is the best, the strongest, the fiercest and mightiest.

The pictures were snapped in the northern Ostrobothnia region of central Finland

"Each male claims a small patch on an open field - most often a bog or a field - and they defend their patch against the other males, and everyone tries to oust their neighbours and claim their territory.”

The show of strength by the male grouse happens during the mating season

According to the 56-year-old, this behaviour is not just limited to the male of the species - as the females also get involved in some of the action.

He said: “They too start to get into a fighting mode, trying to make sure they are closest to the best male, and the first in the queue for mating.”

The mating season for grouse is in spring

Markus has been studying birds and their behaviour for the past 40 years, often travelling around Finland hoping to snap them in their natural habitat.

“I use my material to make books and exhibitions, to show people the birds around us, and how they live their lives,” he added.

"You don’t have to travel to exotic places to see interesting, exciting things.