@article{PB-BC7B5338EFC14120EEE7,
  title = {Magnetic compass of migratory Savannah sparrows is calibrated by skylight polarization at sunrise and sunset},
  author = {Rachel Muheim and Susanne Åkesson and John B. Phillips},
  journal = {Journal für Ornithologie},
  year = {2007},
  doi = {10.1007/s10336-007-0187-4}
}