200400 600-800 
—<———— 
Fig. 28.—General breeding distribution of the purple mar- 
The outlined range may include large sections in which 
lations of the species are thin or even absent because of 
nature of the terrain and paucity of suitable habitat. The 
er range of the purple martin is in South America, but 
ly known. 
sical factor, or any single factor. One factor diffi- 
to evaluate was inconsistent care of nest boxes. 
» factors most often mentioned in the literature 
flecting martin populations are weather (Mussel- 
1 1966, and Bartel 1947), and competition from 
8€ sparrows, starlings, and house wrens (Ridgway 
», Barnes 1890, Bartel 1946, and Widmann 1905) . 
ig (1937) felt that martins declined with the de- 
¢ of horse stables, reflecting a reduced fly popula- 
. There are no precise quantitative data to show 
influence of any of these factors on martin popula- 
8. However, a crash in the martin population was 
tved widely in the Midwest in 1966, coinciden- 
’ with subfreezing spring temperatures after the 
tins had arrived, and dead martins were found 
nd around nest boxes (Petersen 1966, and Mussel- 
| 1966). Martin populations were still somewhat 
ressed the following year in Illinois and Iowa 
fersen 1967) . 
ing Cycle 
Though there are few published data on the nest- 
ycle for any Illinois population of purple martins, 
Widmann’s (1884, 1922) studies of the species in the 
St. Louis, Missouri, area are important and pertinent. 
He estimated the time requirement for a successful 
nesting, to fledging, to be about 8 weeks—2 for nest 
building and egg laying, 2 for incubation, and 4 for 
the development of the nestlings. He believed that 
an additional 2 weeks of parental care were required 
after fledging. Widmann’s figures are similar to those 
of Allen & Nice (1952) for a Michigan population, 
except that they recorded incubation periods of 15- 
19 days. 
The early spring arrival of the purple martin in 
relation to its nesting has been a point of discussion 
by Widmann (1922), Johnston & Hardy (1962) , and 
others. Though nest building has been recorded as 
early as March 24 in southern Illinois (Johnston & 
Hardy 1962), and April 18 in the north (Gault, un- 
published notes 1906), the earliest egg date is “mid- 
April” in the south; it was May 5 in the north (Fig. 
29), showing lapses of 2-3 weeks between nest build- 
ing and egg laying. Widmann (1922), and Johnston 
& Hardy (1962), suggested that the early arrival and 
nest occupancy of the martin is related to intraspe- 
cific competition for cavities, going back to the times 
when only natural cavities were available, and prob- 
ably in short supply. 
Nest building, which is carried out by the female, 
is prolonged, interrupted sometimes for days at a time, 
particularly during inclement weather (Widmann 
1922, and Johnston & Hardy 1962). 
A variety of materials have been used for nest con- 
struction—paper, dry leaves, twigs, catalpa pods, as- 
paragus stalks, dry grass, rags, string, straw, weed 
stalks, cow manure, and mud, the mud being used to 
form a solid wall or mat that slopes down from the 
box entrance to the rear of the box (Widmann 1880, 
Gault 1934-1935, Johnston & Hardy 1962, Loucks, un- 
published notes 1889, and Silloway, unpublished notes 
1920-1924). These students, as well as Barker (1905); 
observed that martins also often bring fresh green 
leaves to their nests. This behavior seems to be some- 
thing more than just nest construction, as the leaves 
are brought after the nest is largely complete and 
from time to time through the nesting cycle. Leaves 
of pear (Pyrus sp.), poplar (Populus sp.), elm 
(Ulmus sp.), peach and apricot (Prunus sp.) have 
been recorded in Illinois nests (Barker 1965, Launer 
1967, and Reiss 1971), but other species are prob- 
ably used. Various functions have been ascribed to 
this behavior, including: the addition of moisture 
to the nest chamber, cooling of the nest cavity, con- 
cealment of the eggs, and fumigating the nest to dis- 
courage ectoparasites. None of these theories has 
been proved. 
The mid-April laying date recorded by Hardy in 
Southern Illinois may be exceptional (Johnston & 
Hardy 1962), as it occurred in a particularly mild 
spring. He believed that more typically the egg-laying 
31 
