Since my return home, the Dutch naturalists Rosenberg and Bernstein have made extensive collections both in North Celebes and in the Sula islands; yet all their researches combined have only added eight species of land birds to those forming part of my own collection--a fact which renders it almost certain that there are very few more to discover.
Besides Salayer and Boutong on the south, with Peling and Bungay on the east, the three islands of the Sula (or Zula) Archipelago also belong zoologically to Celebes, although their position is such that it would seem more natural to group them with the Moluccas.

About 48 land birds are now known from the Sula group, and if we reject from these, five species which have a wide range over the Archipelago, the remainder are much more characteristic of Celebes than of the Moluccas.

Thirty-one species are identical with those of the former island, and four are representatives of Celebes forms, while only eleven are Moluccan species, and two more representatives.
But although the Sula islands belong to Celebes, they are so close to Bouru and the southern islands of the Gilolo group, that several purely Moluccan forms have migrated there, which are quite unknown to the island of Celebes itself; the whole thirteen Moluccan species being in this category, thus adding to the productions of Celebes a foreign element which does not really belong to it.

In studying the peculiarities of the Celebesian fauna, it will therefore be well to consider only the productions of the main island.
The number of land birds in the island of Celebes is 128, and from these we may, as before, strike out a small number of species which roam over the whole Archipelago (often from India to the Pacific), and which therefore only serve to disguise the peculiarities of individual islands.

These are 20 in number, and leave 108 species which we may consider as more especially characteristic of the island.