This video from the Cornell Lab of Ornithology in the USA says about itself:
Vesper Sparrow singing
26 January 2016
In the evening twilight or early morning, listen for the Vesper Sparrow‘s characteristic song consisting of two to four long, clear notes, followed by musical slurs and trills. These large sparrows are found in grasslands and fields across North America.
Video recorded by Benjamin Clock in Michigan.
Dear Kitty. Some blog 