In spring, thousands of birds fly north to breed in Siberia. Some birds eat grass shoots start to grow at the beginning of the season. This food source is only available for a few weeks and rising temperatures (cause) by climate change can sometimes make the grass grow earlier than usual. This means that some birds are arriving too late to eat the grass, (leave) them without a food source. As more and more land is used for farming, the natural wetlands birds like to search for food are disappearing too.
