REPRODUCTIVE PHENOLOGY AND BREEDING SUCCESS OF THE MONK PARAKEET (MYIOPSITTA-MONACHUS-MONACHUS) IN ARGENTINA

The breeding biology of the Monk Parakeet (Myiopsitta monachus monachu s) was studied in Punta Blanca, central Argentina (34 degrees 56' S, 5 7 degrees 39' W). Observations on 9 communal nests (13 breeding chambe rs) were made during 1988 and 1989. The median date of the first egg f or each year was 14 and 31 October (the median for 2 years was 16 Octo ber). Clutch size ranged from 5 to 12 eggs, averaging 6.9. Incubation took 23.6 days and hatching was asynchronous. Mean hatching success fo r clutches was 52.2%. Only 17% of the nestlings fledged. Only 8.9% of the total eggs laid resulted in fledglings. Predation by Opossums (Did elphis) and Black Rats (Rattus) was the main cause of mortality at nes ts (82%), but 17.9% of the nestling mortality was due to intraspecific s attacks, including sibling aggression.