58 per cent (98 birds). For.adults, the mean annual mortality rates 
were estimated to be about 28-37 per cent. These are considerably 
lower than rates computed by Schifferli (199) for Swiss birds. 
No convincing explanation was offered to acccunt for the 
high productivity of successful females (l young per brood) and the 
low mortality rates here encountered. The oldest bird among 98 
records had reached 10 years of age. 
113 
