Contained in the bird collection are about 2700 egg entries (complete or parts of clutches). In some cases, also whole nests are included. The eggs mainly come from Norwegian/Nordic bird species.
A big part of this material come from private collections of the zoologist Herman Friele (1838–1921), and the medical doctor A. B. Wessel (1858–1940) from Eastern Finnmark.
Special investigations of breeding biology in some species (especially waders/shorebirds) have also resulted in material of high quality. The remaining collection largely consists of more randomly collected eggs that for some reason did not hatch and were deserted.