Add a contradiction to the given sentence.
The birds flew south for the winter, but at the same time, they stayed in the north.
The birds flew south for the winter.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:
Add a contradiction to the given sentence.

### Input:
The birds flew south for the winter.

### Response:
The birds flew south for the winter, but at the same time, they stayed in the north.