On my recent trip to Northern Germany I was walking on a path bordering a field out in the country, a large field with short stubby grass which had recently been cut. As I was concentrating on listening to the melodius fluting song of a Common Blackbird (turdus merula) in a nearby bush I became aware of another sound, a series of eery low pitched scratchy sounds just beyond the edge of the field, it seemed, but the exact distance was hard to pin-point In the increasing darkness I gradually made out the dark silhouette of a game bird crouching near a clump of grass in the middle distance, from which the sounds seemed to be coming. I recorded a section and identified it as a grey partridge (link to audio file)
Spectrogram & waveform using Raven Lite 1.0:
Although I grew up in Germany in the 50's and early 60's I had never heard this sound before nor had I seen grey partridges which were supposed to have been quite abundant, although less so today because of intensive cultivation and loss of habitat. It was introduced to North America where it is also known as "Hungarian Partridge". It was extensive hunted in the UK and is currently on the Red List there.