For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jimfunk:routesia/openSUSE_Tumbleweed/home:jimfunk:routesia.repo
zypper refresh
zypper install bird
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jimfunk:routesia/15.5/home:jimfunk:routesia.repo
zypper refresh
zypper install bird
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jimfunk:routesia/15.4/home:jimfunk:routesia.repo
zypper refresh
zypper install bird