Tips on sexing Delawares, Speckled Sussex, and Australorps?

[annmarie]

Does anyone have any tips on sexing Delawares, Speckled Sussex, or Black Australorps? I know some breeds have more obvious clues like coloration that show up at an early age and I'm hoping these breeds might. A friend and I are expecting our box of chicks from Sandhill today and I'm hoping it won't take forever and a day to distinguish the roos from the pullets. Thanks!