Clocked this snoozing (unfortunately I must have woken him) gull as I was almost home after my lunchtime walk and was puzzled by the string. Was it a trophy he wasn't letting go of or some debris he'd half swallowed and got snagged or stuck? He didn't seem fussed by it and certainly wasn't going to let it go. But, he WAS blissfully asleep with it still in his mouth!

Who knows?
We simply don't know!