The bird collection is among the largest in the world. The material includes skins, skeletons, alcohol preparations, eggs, as well as blood and tissue samples. The collection of skins is one of the world's largest and most species-rich, with 65% of the world's species represented. The skeleton collection, on the other hand, is relatively incomplete because it was more common to put whole birds in alcohol during collection trips in the past, rather than skeletonizing the animals. The last major review of bird types at the Swedish Museum of Natural History was made by Nils Gyldenstolpe in 1926, and the list includes a total of 283 types.