The collared turtle-dove (Streptopelia decaocto) and the turtle dove are common synanthropic bird species. The collared turtle dove in particular comes to close contact with farm animals, including with tuberculosis-infected small poultry on farms. It can thus be infected by avian mycobacteria and to become their further source and disseminator. Elucidating the occurrence of avian mycobacteriosis in turtle we examined 218 specimens of the collared turtle-doves and 22 specimens of turtle-doves taken in habitats with different epidemiological setting. We found no pathomorphological tuberculous lesions and isolated no mycobacteria from organs or the contents of intestines in any of them, though we also examined turtles living near poultry farms infected with tuberculosis or near farms where avian tuberculin-positive cattle was reared. Under the same conditions we found repeatedly, e.g. in sparrows, both the tuberculous lesions and mycobacteria. The turtle dove can thus be considered as very resistant to avian mycobacteria and the occurrence of avian mycobacteriosis can be regarded as rather exceptional. The susceptibility of the collared turtle-dove to avian mycobacteria was verified also by experimental infections. After intramuscular infections of M. avium serotype 2 suspension, we demonstrated macroscopic tuberculosis lesions only in the site of inoculation from day 21 onwards. The histological lesions were found in the liver, spleen and bone marrow from day 28 after inoculation. However, mycobacteria were isolated from various organs and tissues as early as 12 days after inoculation. Attempts to demonstrate tuberculous lesions and to isolate mycobacteria from the intestines failed. No tuberculous lesions produced in turtle dove within the period of 122 days after peroral infection by food contaminated by TBC poultry livers and bacteriologically examined was negative too. After free contact between TBC poultry and turtle doves the sporadic histological TBC changes in liver were found after 180 days and in one case mycobacteria were isolated from the liver and muscle after 157 days. The transfer of M. avium from TBC infected turtle doves pigs and poultry was successful. After 45 days of join contact among TBC turtle doves, healthy pigs and poultry in stables and after further stay of pigs and poultry in contaminated environment for additional 65 and 175 days, respectively. In the course of the experiment, 105 days after its onset, marked reaction to avian tuberculin was demonstrated in one pig. Simultaneously with it, the TBC lesions in mandibular and mesenteric lymphatic glands were found. In one pig, mycobacteria were isolated from those suspectedly affected lymphatic glands.(ABSTRACT TRUNCATED AT 400 WORDS)