Age categories P1 – P7 of Sooty Tern chicks on Ascension Island – South Atlantic
The following images show the age and plumage development of Sooty Tern chicks.
P1. Downy – chick covered with down 0-10 days
P2. Small Wings – scapular feathers appear 9-20 days
P3. Head Moulting – feathers appear on the crown, mantle and breast 19-29 days
P4. Down on Face – down restrIcted to face, lower belly and rump 28-36 days
P5. Tail cocked – tail coverts grow and tail appears “cocked” 36-43 days
P6. Short Tail – rectrices all about same length, wings <200mm 42-50 days
P7. Tail forked - outer rectrices considerably longer than inner, wings >200mm 50-65 days