TREE SWALLOW 
BREEDING RECORDS 
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Fig. 5.Breeding records for the tree swallow in Illinois. 
swallow. John Schwegman (personal communica- 
tion) noted that starlings (Sturnus vulgaris) took 
over cavities that tree swallows had used at Mermet 
Lake (Massac County) . 
Natural cavity nests have been recorded most 
frequently in willows, often stubs standing in water, 
with the nests 4-15 feet high. 
Nesting Cycle 
Very little has been published on the nesting 
cycle of the tree swallow in Illinois, though an 
excellent study by Peter Dring of Willow Springs 
is in progress. At present there are no published 
data on nesting success or productivity, and no 
data on any phase of the cycle from southern 
Illinois. 
In Tazewell County, Loucks (unpublished notes, 
1892) found tree swallows building nests as early as 
April 27. In the north most of the egg production 
comes in May, with laying starting as early as May 
4, but some egg production occurs in June and July, 
as late as July 10 (Fig. 4). 
Clutch sizes from the literature or museum co 
lections (24 nests) varied from four eggs (16 pe: 
cent of nests) to seven eggs (8 percent) with si 
egg clutches (42 percent) and five-egg clutches (3 
percent) being most common. 
Fall Migration 
We do not know how early the southward fligh 
begin, but we detected notable population chang 
in central Illinois by the end of July (Fig. 4 
Northern Illinois departure dates have ranged 
different places and different years from mid-Augi 
to November 7 (Clark & Nice 1950, and Ford 1956 
Along the major rivers in western Illinois, lar 
ageregations of tree swallows may be expected fre 
late July to at least mid-October . (Fig. 4). Da 
counts of several thousand birds are not unust 
along the Mississippi River, and in the St. Lo 
area Anderson & Bauer (1968) have recorded t 
of thousands per day (see also Jones 1933)e 
the same area Wilhelm (1954) reported 300 as | 
as November lI. 
We have found much smaller numbers of 
grant tree swallows in the Rock River Valley tl 
in the Mississippi and Illinois valleys. On the east 
side of Illinois, even in the Ohio Valley, no one 
reported numbers of tree swallows comparable 
those seen in the west (Fig. 4). However, relatin 
little study has been given to the Wabash and O 
valleys, and higher populations than are pres¢! 
known may ultimately be found there. Hess (19 
spoke of seeing “armies” of tree swallows in ¢ 
central Illinois in September, but there is no 
to interpret his statement in numerical terms. 
contrast to eastern Illinois generally, northeas 
Illinois may have large numbers of tree swall 
Nolan (1955) recorded a peak population of 2 
birds at Fox Lake on October 1, 1954. 
We saw many more tree swallows in the 
(August—October inclusive) than in the sp 
(March—May inclusive) . The ratio was | bir 
the spring to 62 in the fall in the north (1968 
to 18 in central Illinois (1969), and 1 to | 
southern Illinois (1967 and 1970). It is our 
pression that in the fall swallows tend to sta 
the same areas for extended periods so that 
same birds are counted over and over 4 
whereas in the spring they move through the 
more quickly. This behavior would have a 
bearing on the spring-fall ratio, but we still be 
that the fall population greatly outnumbers 
spring population. 
Winter Records 
The regular winter range of the tree sw 
lies no closer to Illinois than a few hundred © 
to the south and east (Fig. 3), and the al 
record of a flock of 200 near Springfield on D 
