Table 4. Observed and expected (in brackets) number of host species breeding in cavities, on ground and openly on trees in three bird fly species.

Species	Cavity	Ground	Trees
O. avicularia	7 (8.0)	12 (15.3)	16 (11.7)
O. chloropus	8 (10.3)	24 (19.7)	13 (15.0)
O. fringillina	7 (3.7)	6 (7.0)	3 (5.3)