Is it a bad thing that the birds eat what the dog doesen't? What time do you have off for school vacation? You go to school for a longer period of time than in the states.
I see where this feeding thing would make you upset when you depend on someone to help and they don't follow through.
Another thing could you get the food ready the night before (put it in a sealed container like a ice cream bucket) so you would just need to dump it in his dish?