Twisting and writhing in the spring sunshine - these two males adders are captured performing a rare 'dance' to establish which one is the boss.
The striking reptiles, sporting their distinctive stripey livery, are seen chasing one another across grassland in the Scottish Highlands.
The tussle among the dried bracken and moss lasted just a few minutes before one of the snakes slithered away to fight another day.
The age old ritual - where male adders fight other males which stray onto their territory or threaten their female partners - is rarely captured on camera.
But the scene was caught by wildlife photographer Colin Black, 49, earlier this week on the fringe of the Cairngorms National Park.
Colin, from Aberdeen, said: "This time of year the adders start coming out of hibernation and the best time to catch them is at noon when the sun is high in the sky.
"I staked out an area where I know they will sun themselves and was rewarded by watching two of the males fight each other.
"Normally a male and female will pair off and if another male strays too close then they will perform this special 'dance' or wrestling match to establish which one is dominant.
"I watched for a few minutes as they tussled with each other before one of them gave up and slinked off.
"These were to quite large males, they each were about 70cms long."
The common European adder - Vipera berus - is the only venomous snake native to the UK.