Macaroni penguin female are similar in appearance; males tend to be slightly larger. Males also bear relatively larger bills, which average around compared to in females; this feature has been used to tell the sexes apart. Immature birds are distinguished by their smaller size, smaller, duller-brown bill, dark grey chin and throat, and absent or underdeveloped head plumes, often just a scattering of yellow feathers. The crest is fully developed in birds aged three to four years, a year or two before breeding age. Macaroni penguins moult once a year, a process in which they replace all of their old feathers. They
Macaroni (horse) entering the straight and held off the sustained challenge of The Oaks winner Queen Bertha to win by one and a half lengths. At Newmarket in October he walked over in the Select Stakes and was then retired to stud. Macaroni was retired to his owner's stud at Hooton until 1866 when was sold for 7,100 guineas to Baron Meyer de Rothschild who moved the stallion to his stud at Mentmore. Macaroni sired several successful racehorses, including the 2000 Guineas winner Macgregor but was more notable as a sire of broodmares. He was the damsire of the Triple Crown winner