SIRDS COUNTED PER DAY 
lO 20 30' 9 9 29 
JUL AUG 
ouse sparrows driving phoebes away from nest sites on 
dings. If true, this competition with sparrows could 
n explanation for low phoebe populations in urban 
lential habitat. In recent years we have also seen the 
by house sparrows of phoebe nests under bridges. 
f the phoebe population of Illinois is showing a trend 
ther direction, decreasing or increasing, present data 
1ot adequate to show the trend. Through the years a 
CENTRAL 
lO 20 30 10 20 30 3 i) 
SEP OCT NOV 
number of authors have reported the phoebe population 
to be declining in Illinois, and there appear to be periodic 
population “crashes” in this species (Mayfield 1951, 
Nolan 1958) similar to those seen in the bluebird (Sialia 
stalis) population (Graber et al. 1971). Hodges (1953) 
estimated that there was a 70-percent decline of the 
phoebe population in 1953 in the Rock Island-Davenport 
area. James’ (1960, 1961) analysis of population data 
a1 
