SPRINGWATCH viewers were left traumatised and upset following tough scenes in Monday’s episode.
The long-running BBC nature programme returned for its 20th series last month.
Presenters Chris Packham and Michaela Strachan introduced the latest instalment.
However, fans were devastated when the pair revealed their reed bunting chicks had been attacked by an adder snake.
Chris, 63, narrated the heartbreaking scenes as viewers were shown what had happened.
He issued a warning beforehand: “We are able to witness things which we aren't always able to see.
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"Some things are absolutely fascinating, and our duty of course is to report all of this to you and to show you what is really happening out here. We tell you the complete truth.
"Sometimes, however, the truth is quite hard to swallow.
"This is going to be a tough watch so if you are feeling a bit squeamish tonight, you may not want to find out what happened to our reed bunting chicks."
A clip of the mother and four chicks played, as Chris' voiceover explained: "We had four of them in the nest, down on the marsh, they were doing well and both adults were coming in frequently with food.
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“Here we see the female coming in and bringing them some food but look at this.
“Out of nowhere, an adder appears. The female flees obviously immediately and the snake bites two of the youngsters, clearly envenomating them because they are almost immediately still. Either incapacitated or dead.
"Then it moves around and thinks of taking one of those youngsters, grabs hold of it by the head and once it has got a grip it withdraws the dead youngster from the nest to a place where it will be easier to swallow. It's extraordinary."
The camera then returned to Chris and Michaela live from their location, as Chris added: "When I grew up, adders, they eat small mammals, particularly young small mammals they would get from their nest."
Not long after, the clip of the chicks returned as Chris informed viewers of even more bad news.
"We have now got one dead chick that it has envenomated and two living chicks in the nest, the adder returns and if you look carefully you can see the bulge in its body where it has already swallowed the other chick.
"This time it slithers around the back of the neck, clearly using its tongue to sense this.
"It was bound to return, it comes in the back and the dead chick would be the obvious target, not moving, easy to deal with, easy to take away. It nuzzles around, it ignores it and attacks another chick.
"It doesn't wait for the venom to take effect and it drags the chick out the back of the nest alive.
"It is a grizzly watch but it is simply extraordinary that we are giving this insight into this behaviour."
Many fans were left "traumatised" by the clips, with one remarking on X: "Footage of adders attacking chicks. Fascinating. Gory. Sad. But circle of life."
"I decided to leave the room. #Springwatch," another added as a third penned: "Those poor chicks taken by that snake. Brutal. So hard to watch."
Everything you need to know about Springwatch
Springwatch began in 2005 and showcases British wildlife during the changing of the seasons in the United Kingdom
It's presented by Chris Packham, Michaela Strachan, Iolo Williams and Megan McCubbin
Chris and Michaela joined the show from 2009 and 2011 onwards, respectively
Just like last year, the long-running series is broadcasting live from RSPB Arne in Dorset
A total of 19 series have aired to date, with the 20th edition now on air on BBC Two
The show’s popularity over the years spawned spin-offs Autumnwatch and Winterwatch
Autumnwatch began as a one-off, but was expanded into its own series from 2006 to 2022
Last year, the Beeb cancelled Autumnwatch citing budget concerns and having a smaller audience than its counterparts
The original presenting line-up for Springwatch included comedian and conservationist Bill Oddie, television presenter Kate Humble and naturalist Simon King
Bill, known for his work with The Goodies, exited the programme in 2008, followed by Simon in 2010 and Kate in 2011
A fellow viewer asked: "Omg those poor chicks!!!! #Springwatch @ChrisGPackham How could you devastate us like this?" as another commented: "I’m traumatised. #springwatch."
Some, however, defended the footage being shown, arguing it was nature taking its course: "He did warn us. It's the circle of life unfortunately.
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"The snakes need to eat just as much as the chicks. The snake will be a bigger animal dinner."
Springwatch airs on BBC Two and BBC iPlayer.