Difference between a male and female stork (2 Viewers)

My question is how can I make difference between male and female white storks? I have made a photo to three storks, two (kid and parent) have rd bill, the other kid almost black see photo in link below.

https://plus.google.com/u/0/photos/114043667362461482276/albums/5764751419702179185/5764751536437438290?pid=5764751536437438290&oid=114043667362461482276

The black bill identifies a youngster. Adult males are slightly larger than females, but it's basically impossible to tell the sexes apart.

Actually I think I see three youngsters in your photos, with patchy bills - part black and part pale pink, different colors being more visible depending on whether the bill is in shadow. I see one adult on the nest, with a vivid pink bill (same as all the adults on the ground).

Thanks...

red bills - adults, black bills - young juveniles.
adult male has a stronger bill with a more accentuated gonydeal angle (the angle on lower mandible on the distal part of bill) than female but differences are subtle.