My cat, Spot, makes these weird noises when his feathered friend comes around [Video]

I find it adorable, but should I be concerned? I'm not sure if Spot is trying to provoke the bird or something, or if it's just for fun. Any insights would be great

That is perfectly normal.  He is telling the bird "Gonna getcha, gonna eatcha"  My ladies will sit and do that to the bluejays and the squirrels that get near the windows or the back porch screens.  Just sit and enjoy the show.

My cats both make similar abnormal meows when they see birds outside. I think it's because indoor cats rarely see birds and tend to get extra excited when they do finally see one. My cats go wild for the pigeons that nest on the windowsill next door. One coo from a pigeon is enough to send my cats into a frenzy, trying to find the best window to see it from and meowing their butts off.

My back porch is 6x16 with screens from floor to ceiling height on three sides (see my profile picture) and the ladies see all kinds of birds and squirrels every day.  They still react with the same behavior as yours.  They chatter and twitch and swish their tails like mad. 

That is so funny! He sounds like a baby crying.

Awwww he's so gorgeous!!!!. But yes those sounds are normal 

I'm not sure Spot sees the bird as his 'friend' 

It looks like the bird may even be teasing him.

I love the way he yawns at the end, and then keeps on going.. great video