On 22 April 1944 Béla Bartók wrote to his son, Peter:
Spring has now indisputably arrived. A kind of ‘kutyafa’ (dogwood) is in bloom, like acacias flowering at home. The birds have become completely drunk with the spring and are putting on concerts the like of which I've never heard. They start with puty-puty-puty ./../../. and end up with various new bird sounds (clearly from later arrivals). Thekeeps on creating more and more variants.