Taste 8.— Plants used by brown thrashers as nest sites 
excluding 212 nests found in a special study of osage orange 
edgerows in central Illinois). 
Percent of Total Nests 
Plants North Central South 
(116 Nests) (136 Nests) (62 Nests) 
sage orange (Maclura pomifera) 39 41 5 
ultiflora rose (Rosa multiflora) 
foo 20) Se 5 8 24 
ed cedar (Juniperus virginiana).. 1 1 31 
fae ees Sp.)............. 10 5 2 
meysuckle (Lonicerasp.)..... .2(shrub) 2(shrub) 13(japonica) 
vabapple andapple (Malussp.) 4 2 3 
Imes sp.).............. 3 1 3(alata) 
awthorn (Crataegussp.)....... 6 18 a 
voseberry (Ribessp.)......... 6 3 
x-elder (Acer negundo)........ 3 2 
ulbermy(Morussp.).......... 2 3 
ac (Syringa vulgaris)......... 1 4 2 
Memeeeercun sp.)............. 3 Ae 2 
amble (Rubussp.)........... 3 1 : 
Wea SP.)............. 1 1 
ver birch (Betula nigra)....... 1 1 «6 
ssafras (Sassafras albidum)..... |. a 5 
gwood (Cornussp.).......... 4 
Id plum (Prunus americana)... . . 4 
‘ginia creeper (Parthenocissus 
ES) 3 
ck orange (Philadelphussp.).. .. nf 3 
impet-creeper (Campsis 
Gee... ... 7 a 3 
ckhaw (Viburnum prunifolium ), 
MGMEIeUTTOUSD............. 2 
CU ke 2 
-enbrier (Smilax sp.)........ 
ersweet (Celastrus scandens). . . 2 
rea (Spiraeasp.)............ Ae ae 2 
wherry (Symphoricarpos SEs ert 1 
zel (Corylus americana). ...... 1 
den-bell (Forsythiasp.)...... i! oe 
uty-bush (Kolkwitzia amabilis) . . 1 
sting Cycle 
Banding data provided by Lyon (1921), Lincoln 
27), Bartel (1942, 1943), and Jurica, et al. (1959, 
0, 1962) show that at least some of both juvenile and 
Ut thrashers return to the same summer home after 
migration, but there are no quantitative data on year- 
ear homing and survival. 
Courtship and territorial behavior by thrashers must 
in almost immediately after the birds arrive from the 
tering grounds (Fig. 20). Several authors refer to the 
that the males arrive singing. To Ridgway (1889), 
© most listeners, the thrasher was a superior songster. 
- Song, sweet but loud, is often delivered from the top 
tree, and characteristically has fewer repetitious notes 
tally not more than three) than the song of the 
Kingbird, Ridgway (1874), who spent many years in 
shington, D.C., felt that the thrashers of southern 
ols sang more vigorously than those in the East. In 
northeastern Illinois Gault (1901) noted that thrashers 
begin to grow listless during June, and the singing is much 
reduced. In addition to the loud song, there is a very 
soft, more complex whisper song, usually uttered while 
the bird is low in a shrub or thicket, and probably heard 
most often in the early part of the nesting season (Coffin 
1915, Schafer 1916). During much of the nesting season, 
and in late summer especially, an observer is more likely 
to hear the loud “smack” alarm call than the song. 
The nesting season, the period between the onset of 
nest building and the fledging of the last young of the 
year, lasts from about April 1 to August 12 in southern 
Illinois, from April 15 to August 21 in the central zone, 
and April 15 to August 25 in the north (Pio20 ein 
terms of what most of the thrasher population does, how- 
ever, the nesting season is much shorter than these dates 
indicate. For example, most of the egg production occurs 
in April in southern Illinois, and in May in the central 
and north (Fig. 23). 
The minimum time required from the onset of nest- 
building to the fledging of (three) young was 32 days for 
a nest in Ford County. In this case nest construction 
required 4 days, egg-laying 3 days, incubation 13 days, and 
the nestling stage 12 days. One nest we observed which 
looked complete when it was found went 13 days before 
the clutch was started. Incubation periods were nearly 
always 12%-13 days, but one clutch in the north took 14 
days. One female incubated eggs with dead embryos at 
least 16 days but abandoned by the 22nd day. Young 
usually fledged in 12 or 13 days, but one stayed at least 
14 days. 
Data on the plants used for nest sites are presented in 
Table 8. Most thrasher nests are found 2-5 feet above 
ground in northern and central Illinois, and 3-6 feet in 
the south (Fig. 24). About 5 percent of the nests recorded 
in central and northern Illinois have been ground nests, 
but there are apparently no such records for southern 
[linois. Nearly all ground nests have been near shrubby 
cover, frequently at the bases of shrubs, but Kennicott 
(1853-1854) mentions finding several nests under fences 
in the prairie. The height of nests in osage orange trees 
in Ford County tended to vary with the season as in the 
case of the mockingbird in the south, with the early nests 
being lower (April-May: 3 feet; June-July: 5 feet). 
Brown thrashers lay their eggs early in the morning 
(Silloway 1906) and on consecutive days. Most April- 
May nests receive four eggs and most June-July nests 
have three eggs (Table 10). Clutches of five eggs are 
decidedly more common in the northern region of the 
state than in the central or south (Table 11). In some 
years large clutches are particularly prevalent, Cou ein 
1933 (Blocher 1933) and 1914-1915 (Sanborn & Goelitz 
1915), but the cause of this annual variation is unknown. 
True two-egg clutches are apparently very rare; most 
nests found with two eggs have probably lost eggs one way 
or another. One nest we observed received seven eges 
from two females, in two laying sequences —a four-ege 
clutch laid May 13-16 and a three-egg clutch laid May 
29 
