Because of this , they are not used widely in modern poultry production , except for gamekeeping .
These devices require time and skill to fit and therefore have problems of practicality given that commercial flocks usually contain several thousands of birds .
Because of this , thousands are not used widely in modern poultry production , except for gamekeeping .
These devices require time and skill to fit and therefore have problems of practicality given that commercial flocks usually contain several thousands of birds .