THE EFFECTS OF PARENTAL AGE AND WEATHER ON BREEDING PERFORMANCE OF COLONIAL AND SOLITARY TREE SPARROW (PASSER-MONTANUS (L))

250 nestboxes were arranged, 25 with 50 m separations to simulate soli tary breeding and 25 3-5 m apart to imitate colonial breeding in each of 5 plots in order to study tree sparrows (Passer montanus) in a subu rban area of Budapest, Hungary (19-degrees 04' E, 47-degrees 41' N). N estlings were marked with coloured rings and reproductive performance of parents which bred in their birth place was related to daily mean t emperature and humidity between 1987-1992. Daily mean temperature affe cted the productivity of both colonial and solitary parents in first b rood and that of colonial parents in second brood, daily mean humidity affected the breeding performance of colonial parents in first and se cond broods. No effect was recorded for third broods. Parents which pr oduced fewer fledglings than average in previous broods produced more than average numbers of fledglings in second and third broods. It is s uggested, that multibreeding with small clutches in each brood is an a daptive adjustment by tree sparrows to effects of fluctuating weather conditions. In first broods, when adverse weather conditions affect bo th colonial and solitary breeders, colonial nesting is more advantageo us; in second broods, when weather conditions affect only colonial bro ods, solitary nesting is more advantageous for rearing offspring. The effect of female age on productivity was greater than that of male age . Pairs in which both parents or the female were in their first breedi ng season, reared fewer offspring than pairs in which females were old er. The mean total productivity of subsequent broods was lower for par ents which bred through three, four or five years than for the parents which bred only in first and second year in their birth place, i. e. low performance in early breeding activities results in good survival prospects in the tree sparrow.