These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.99 s (backtrack: 0/20).

[ebuild  N     ] acct-group/bird-0-r2::gentoo  0 KiB
[ebuild  N     ] acct-user/bird-0-r2::gentoo  0 KiB
[ebuild  N     ] net-misc/bird-2.19.0::gentoo  USE="client filecaps -custom-cflags -debug -libssh (-selinux)" 1517 KiB

Total: 3 packages (3 new), Size of downloads: 1517 KiB