The bird protection charity, the RSPB has warned that as the cold weather kicks in, birds in the UK could struggle to get enough food to survive.
As the days get shorter, birds don't have enough time to look for food.
Snow and ice can make it really hard for them to get to it.
And it's not just food they need.
Water's really important too so they can keep their feathers clean to stay warm through the cold months.
To get people's attention, the RSPB has come up with Feed the Birds Day, this Saturday to encourage people in the UK to get in the habit of leaving food out for our feathered friends.
According to the charity, just leaving out some seeds, nuts and leftover scraps of food could make a real difference to help save birds' lives this winter.