Resumen de Freqüència de postes mixtes en el gènere Parus
Routine inspection of 1O00 nest-boxes from 1985 to 1990 in iwo areas of Catalonia (NE Spain) gave a total of 7 mixed clutches of tits out of 1245 broods (0, 56%). Mixed broods appeared between P. Cristatus and P. Ater (5, 71% P), major and P. Caeruleus (0, 99 %) and beiween P. Caeruleus and P. Ater (0, 14 %). Jhis phenomenon is probably related to intense competition for nest-boxes, and may have implications on possible future hybridization of these species.
