range are still needed to complement the nesting statistics reported 
by Hammond and Henry (199) and make this general picture of popula- 
tion dynamics a reliable one. 
Suemary 
Of 102 marsh hawks shot in their first year of life (August 1 
to July 31), about 80 per cent were shot in the first 5 months. For 
8 adults reported shot, this value was 56 per cent. During this first 
year of life, a mortality rate of the order of 60 per cent was indicated 
in a sample of 99 birds. The mean adult mortality rate in this small 
sample was 30 per cent. While both these statistics must be considered 
as preliminary results only, they appear to imply that marsh hawks 
one year old contribute very little to the annual production of young. 
87 
