9 40080080 
a 
miles 
Fig. 23.—General breeding distribution of the cliff swallow. 
outlined range may include large sections in which pop- 
ons of the species are thin or even absent because of the 
re of the terrain and paucity of suitable habitat. Cliff 
ows winter mainly in the southern half of South America. 
‘sonal communication) found exceptional num- 
near Havana, in central Illinois (Fig. 24). Sim- 
y, Anderson (1963) found exceptionally high pop- 
ions, many thousands, in the St. Louis area during 
second week of May, 1963. Our counts for central 
southern Illinois in other years were much lower, 
the marked annual variation precludes any com- 
{ on possible regional variation. The migration 
ls study over a long period of years. 
vault (unpublished notes, 1892) witnessed the 
al diurnal migration of cliff swallows near Glen 
n on May 15, when he saw flocks moving directly 
h. There is no other reference on, or description 
he actual migration flights. 
‘ibution 
the general distribution of cliff swallows is shown 
ig. 23, and the Illinois distribution, so far as it has 
' recorded, in Fig. 25. There are no recent nesting 
rds for central Illinois. It is our impression that 
tange of the species in Illinois has been steadily 
ling to the north, leaving only relict populations 
| few places, and most of the state population 
now is probably in northwestern Illinois. Jo Daviess 
County has long been a dependable haven for this 
species (Kennicott 1853-1854) . 
We hope that further exploration of stream cliffs 
and bridges will turn up additional colonies through- 
out the state. Besides the nest records plotted (Fig. 
25), there are breeding records for Cook, Lake, Cham- 
paign, and Piatt counties by Goelitz (1917), Ogle 
County by Allen (1868), and Sangamon County by 
Eifert (1945) , but definite localities were not specified. 
There are no Illinois references on cliff swallow dis- 
tribution in relation to soil types, but Butler (1891) 
believed that the swallow was almost strictly an up- 
land species in southern Indiana because of the need 
for clay soils without sand for nest construction (see 
also Buss 1942). 
Nesting Habitats and Populations 
The cliff swallow is generally a colonial nesting 
species, though nestings by solitary pairs also occur. 
We have found single active nests along stream cliffs 
that were at least several hundred yards from any 
colony. Schafer (1920) recorded solitary nests on 
barns, and, at the other extreme, 256 nests on a barn 
(1932) . Most of the colonies recorded, however, num- 
bered between 12 and 100 nests. 
No one has attempted a precise definition of cliff 
swallow habitat for any season, and though there are 
descriptions of nest sites (see Fig. 21) , almost nothing 
has been recorded on foraging habitats. Our few 
records for the nesting season showed cliff swallows 
foraging over grasslands, hayfields, small grain fields, 
and streams. 
Natural nesting sites are cliffs, especially cliffs with 
overhangs, usually along streams. Colonies along the 
Apple and Fox rivers are typical. Most of the pub- 
lished nesting records, however, refer to barn colonies, 
i.e., nests placed under the eaves of barns (Hammond 
1939) , often well away from streams. The use of barns 
as nest sites probably goes back to the early history 
of white settlement. Most of the cliff swallow pop- 
ulation at one time was in colonies of this type in 
Illinois, but such colonies have been declining for 
many years. We know of only one still extant, al- 
though there are probably still several left in the 
northwestern part of the state. 
In general, the breeding population of cliff swal- 
lows in Illinois appears to be in decline. There was a 
particularly striking change in the nesting population 
between 1880 and 1910. Ridgway (1887, 1915) saw 
the status of the cliff swallow change in parts of south- 
eastern Illinois from common to absent. Similarly, 
in east-central Illinois Hess (1910, 1921) found cliff 
swallows common in the 1880's, yet by 1909 he re- 
corded the last known nesting for the area. The same 
pattern was observed by Barnes (1912) in Marshall 
County, and there are many references which show the 
fading population in the Chicago area (Lewy 1943; 
20 
