Talking with food in its beak

When I took this picture, I only spotted the food in the beak. 

I suspect it is an arachnid in its beak. But what I discovered was the bird had no problem singing even with prey in its beak.  

Which got me thinking. I can talk with food in my mouth. With a mouthguard. Smokers can talk with a pipe or cigarette out of one side of their mouth. So why did the dog in Aesop's fable lost the meat or bone when it barked at its reflection in the water? 

Kudos if you spot the nictitating membrane in the bird's eye.