I woke up bleary-eyed the other day to be met with what seemed like hundreds of birds on my house. It was a scene straight out of the famous Hitchcock film - The Birds.
They were in fact a flock of house martins that must have contained 50 or more individuals.
This year, as I watch them strut their stuff on the wing and perform aerobatic displays, I've really become a fan of house martins.
Seeing eight or so individuals can be pretty common on telegraph poles, but the sheer number of the house martins on my house was startling! So what are they doing? Well, I asked Paul Stancliffe from the British Trust for Ornithology (BTO) and he told me that these were pre-migration roosts that contained many adults and young from successful broods. The fledglings had hung around and joined up with their parents and their new young (brother and sisters) to form these large roosts.
They'd gathered next to my house in Wales to get ready to fly to equatorial Africa. It's amazing to envisage a journey that distance for a bird the size of your hand!
In the next few weeks, if the weather conditions are favourable, they'll start their migration southwards. House martins like to fly into a slight headwind so in the event of a slight southerly, the starting gun will go off.
It's strange to think that they prefer to fly into the wind but this way they have more flight control than if the wind is behind them. They will migrate in a succession of hops perhaps stopping off in France and Spain and then crossing the Sahara before getting to their destination in Equatorial Africa.
Where to see them
Although my house seemed to be a suitable roost, Paul said that reed beds are a good place to spot house martin roosts. Radipole in Dorset is a good place and in Wales Newport Wetlands centre is also worth a try.
Find out how you can help survey house martins. And remember to drop me a line using the comment form below if any are roosting in your area.
In the meantime, here's my pick of the best of this week's wildlife web.
Chris Watson is one of the worlds best wildlife sound recordists, from beautiful recordings of Africa to surprising and wonderful sounds of an ants nest. Listen to some of his sounds here: