| Publication Type: | Journal Article |
| Year of Publication: | 2006 |
| Authors: | A. J. van der Graaf, Coehoorn, P., Stahl, J. |
| Journal: | Journal of Ornithology |
| Pagination: | 65–74 |
| URL: | http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:Chapter+4\#1 http://link.springer.com/article/10.1007/s10336-005-0041-5 |