Comment on

• Energy saving in flight formation.

  Weimerskirch H, Martin J, Clerquin Y, Alexandre P, Jiraskova S. Weimerskirch H, et al. Nature. 2001 Oct 18;413(6857):697-8. doi: 10.1038/35099670. Nature. 2001. PMID: 11607019
• Carrying large fuel loads during sustained bird flight is cheaper than expected.

  Kvist A, Lindström A, Green M, Piersma T, Visser GH. Kvist A, et al. Nature. 2001 Oct 18;413(6857):730-2. doi: 10.1038/35099556. Nature. 2001. PMID: 11607031