BIRD added BMP (BGP Monitoring Protocol) support on version 2.14.
As the feature is still in preliminary support, I chose to leave it out of the default options for the port.
From BIRDs website:
The current implementation in BIRD is a preliminary release with a limited feature set, it will be subject to significant changes in the future. It is not ready for production usage and therefore it is not compiled by default and have to be enabled during installation by the configure option --with-protocols=.