CLIFF SWALLOW 
BREEDING RECORDS 
‘STS OR YOUNG 
1950 — 
1900 — 1949 
BEFORE 1900 
IRS OR SINGING 
\LES (JUNE) = 
1950 — qe b 
aN joes gre 
wancocd | 
1900 — 1949 = 
BEFORE 1900 Senay | maha te 
enon 
ao 
Yco®@ 
4 
Fig. 25.—Breeding records for the cliff swallow in Illinois. 
Tecord for Coles County represents attempted nesting by 
swallows in burrows at a bank swallow colony. 
914, and by 1916 there were 3 pairs; by 1920 there 
€ 65 pairs, and by 1932 there were 256 pairs. Cliff 
llows did not generally receive this kind of protec- 
. Fawks (personal communication) recorded a 
n colony of 23 pairs of cliff swallows still in Rock 
: County in 1958, but they had disappeared by 
The problems of the cliff swallow with house spar- 
S$ continue. Every cliff swallow colony we have 
ed in recent years, including those in natural cliff 
» has some sparrow occupancy of nests. 
A worthwhile goal for bird students in Illinois 
id be an annual census of the major nesting areas 
is species. Because most of the colonies are located 
1g a few streams, a virtually complete census of the 
- population could be made fairly easily each year, 
Would clearly show the survival problems of the 
les, 
Despite the interest of many Illinois students in the 
Swallow, there is almost nothing recorded on the 
ing cycle. Egg laying occurs from at least May 20 
he north to June 23 in the south. More study will 
probably show that the egg-laying period extends much 
longer than this at both ends in both regions. There 
are no data for the central region. Schafer (1921, 
1933) recorded that two broods were raised, and that 
one year all young were fledged by July 15. 
There have been no measurements of nesting suc- 
cess or productivity, but a few causes of nest failure 
have been mentioned (other than the house sparrow, 
discussed above). Schafer (1923) recorded nest de- 
struction by a red-headed woodpecker (Melanerpes 
erythrouphalus). Kimball (1889) recorded very high 
mortality of nesting birds in Winnebago County, ap- 
parently from starvation because of unseasonably cool 
weather that had reduced insect food in June right af- 
ter nests had been completed. Kimball estimated that 
only 5 percent of the local population survived, and 
he examined many specimens found dead in nests and 
on the ground near nest sites. The specimens were ex- 
tremely emaciated. Hammond (1939) reported on the 
loss of nests washed away by heavy rains, and Mrs. 
Albert J. Brown of Apple River told us of cliff swal- 
low nests being washed away by flooding. Schafer 
(1932) recorded mortality of nestlings during excep- 
tionally hot weather in June that seemed to cause 
birds to fledge prematurely. Dry weather also had an 
adverse effect sometimes, through its effect on the 
availability of mud for nest construction (Hammond 
1939). Eifrig (1937) felt that the painting of barns 
had an adverse effect on cliff swallows, because nests 
did not stick well on painted barns. 
Cowbird (Molothrus ater) parasitism of cliff swal- 
lows has been recorded in Illinois, but the incidence 
is negligible (Friedmann 1963). 
The tick Ixodes baergi, which is parasitic on cliff 
swallows, especially nestlings, has been recorded in 
Illinois (Kohls & Ryckman 1962), but its influence, if 
any, on nesting success is unknown. 
Fall Migration 
Gault (unpublished notes, 1897, 1900) observed 
diurnal migration flights of cliff swallows on Septem- 
ber 5 and September 16, but the southward flights 
must begin before September. In central Illinois we 
have seen groups of cliff swallows far from any nesting 
area as early as July 30, and in northern Illinois Mr. 
and Mrs. Harry Shaw saw the buildup of nonbreeding 
aggregations of cliff swallows from 50 birds on August 
4, 1971, to about 2,000 by August 13. Our data for 
other years show a similar pattern in northern and 
central Illinois, but aggregations of migrant cliff swal- 
lows appeared later in southern Illinois (Fig. at) rNt 
Cairo, Nelson (1877) noted that the species became 
abundant the last of August. 
In August and early September nearly all of the 
cliff swallows we saw were in badly worn plumage, 
and in August we often saw them basking in roadways 
in direct sunlight, pressing themselves against the hot 
sand. We cannot explain this behavior, but other spe- 
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