Manx shearwaters are truly remarkable creatures, travelling millions of miles in their lifetime and living for up to 50 years, travelling from as far afield as South America to land on Bardsey Island to lay just one egg, in an underground burrow.
We'd arrived on Bardsey with a 24 hour mission: to try and capture some unique footage as the birds arrive at night in their thousands to roost.
The weather was a constant issue as we needed dark skies, preferably some cloud cover and ideally no rain to make filming easier - we weren't asking for much!
The birds won't come into land until it's completetly dark, incase they are picked off by gulls.
Manx shearwaters are perfectly adapted for life on the wing but on land become a clumsy winged beast with long legs built for digging rather than walking.
They tend to shuffle around on their bellies and become an easy target for larger, predatory, black backed gulls.
The blue skies and sunshine when we arrived were a lovely respite from the previous rainy days at Lake Vyrnwy but clear skies meant it was going to be a long, cold night so we knew we were in for a late one.
After a quick bite to eat we loaded up the gear onto a trike kindly driven by one of the local lads living on the island, Ben, who handled the vehicle like a veteran!
Steve, the warden, had picked out a lovely green valley for us to film in, called Nant Tysaf which provided a natural amphitheatre for sound, so Chris Watson our sound recordist was very happy.
The plan was to film the shearwaters using a high tech thermal imaging camera and incase you're thinking about buying one, don't, as they're not cheap!
Using the camera (which didn't require lights) was a nice way to capture the birds in their natural environment and we could also view the heat trails caused by the birds already sat in burrows underground, on their nests.
The birds began to appear around 12.30am, with their 'turkey like' gobbles, drifting in eerily from the dark horizon.
This in turn prompted a return gobbles from their mate, deep underground so if you
multiply this by a few thousand, you get an idea of the noise being generated.
The birds can be away for days at a time feeding, so it's an amazing spectacle to hear thousands of birds returning in total darkness to their burrows.
No-one is sure exactly how they manage this feat, as to my ears the calls all sounded very similar, so I've no idea how they can tell whose who, let alone find the correct burrow in the pitch black!?
I'd heard tales of birds flying into people at night and knocking them out cold so it was an odd sensation standing there, waiting to be struck at any moment by a hapless sea bird on his way home.
The night sky was truly breathtaking - the faint glow of Dublin to the west and Holyhead to the north could be seen but above us, the constellations were glowing and the milky way spread smoothly out across the night sky.
As the hours ticked by, the calls from out at sea came in thick and fast with more and more birds landing.
Simon had set up the thermal camera and was beginning to get some nice results.
The camera settings needed to be tweaked regularly to account for the ever changing drop in temperature and having pointed it at all of the crew, I was apparently losing alot of heat out of my trousers, so I tucked my socks in and hoped for the best!
The thermal camera display showed the land around us as a pinky, red, Martian-like world whilst sea birds appeared white as they flew past.
The only heat emitted by them was from their eyes and beaks which glowed orange in the night air.
Whilst the crew were busy filming sequences, I wandered up the slope, carefully dodging birds as they landed and watching out for ones already on the ground.
Steve and his assistant Richard from the BBFO were busy catching and tagging birds and uploading the data into a laptop that contained a database of every shearwater ever tagged here.
One bird in particular, famous amongst ornithologists, was first tagged in 1957.
She's not been seen this year yet so we'll have to wait and see but she did once go missing for 22 years, so there's still a chance!
It was now around 2am and we were all feeling the cold except for Simon who, enthused with the results he was getitng with the thermal camera, had wondered off into the darkness to find more birds...