Fig. 7.-General North American distribution of the bank 
swallow. The outlined range may include large sections in 
which populations of the species are thin or even absent be- 
cause of the nature of the terrain and paucity of suitable hab- 
itat. The breeding population is particularly spotty in the 
South. The bank swallow winters widely in South America and 
also has a wide distribution in the Old World where it is known 
under the common name of sand martin. 
3 and 4 in southern and central Illinois, and April 
11 in the north, but bank swallows do not usually 
arrive in numbers until after April 20, and the 
heaviest influxes occur around mid-May (Fig. 8). 
In the spring we saw the largest numbers in north- 
western Illinois in 1968, but we do not know whether 
this represents regional or annual variation in the 
population. 
Distribution 
The North American distribution of the bank 
swallow is shown in Fig. 7. The Illinois distribution 
(Fig. 9) is far from adequately known, and the 
large areas with no nesting records in eastern and 
southern Illinois probably contain many bank swal- 
low colonies that have not been recorded as yet. 
Blocher (1922) observed that bank swallows could 
be found almost anywhere along the Green River, 
and colonies are probably present along large 
stretches of all the major rivers (at least the Mis- 
sissippi, Rock, Illinois, Wabash, and Ohio), but 
10 
there are no data on the numbers and spacing 
colonies along any stream in the state. 
Nesting Habitats and Populations 
No one has attempted a precise definition 
bank swallow habitat. Musselman (1921) indicat 
that the species occurred where clay banks a 
water were in proximity. Nesting colonies he 
been recorded in loess, till, clay, sandy, and bl: 
soil banks (Schantz 1923, Strong 1898, Sillov 
1906, Ridgway 1887, and Hess 1910) as well as 
natural cavities in rock cliffs, and in sawdust moui 
(Fig. 10 and 11). Hess (1910) felt that bank sy 
lows preferred black soil to sandy soil in east-cent 
Illinois, but there have been no systematic stuc 
of soil usage by either of the burrowing swalli 
(bank and rough-winged) . Nesting banks h 
varied in height from 5 to 75 feet. 
Nearly all of our observations on foraging b: 
swallows involve either water areas or grassla 
especially pastures (Graber & Graber 1963};55 
bank swallow is a colonial nesting species, and tl 
are no population estimates that take forag 
habitat into account. Beecher (1942) found 
pairs in 1.27 acres, and 20 pairs in 0.25 acre, 
banks in Lake County. Gault (unpublished nx 
1912) found a colony with only 2 pairs, but gre 
of 20 to 200 pairs are more typical. The lar 
colony, with 6,000 burrows, located on a cliff 1 
Rock Island, was reported by Fawks (1938) , 
by 1966 it was down to 250 pairs (Fawks 19 
Bank swallow colonies are at the mercy of 
who excavate the banks, and of those natural fc 
that either erode away the banks or cover t 
with vegetation. However, the same eroding ot 
cavating processes that destroy nest banks also 
them (Ford 1915). At present there are no 
from which to judge whether banks are being 
troyed faster than they are being created. A 
colonies have survived many years. The colon 
Rock Island, for example, is probably at leas 
years old. 
Nesting Cycle 
Information on the nesting cycle of bank 
lows in Illinois is meager. In northern Illinoi 
first noticed these swallows working on their bu 
on April 22, and carrying nesting material on . 
99, but some groups of birds did not even < 
at their nesting banks until May 10. Further s 
in Macoupin County, Silloway (1906) saw bu 
being dug on April 25, and in the St. Louis, Mis 
area Widmann (1907) noted that most pair 
not begin nest building before May 5. Bi 
depths recorded in the north by Petersen (pel 
communication), A. C. Murchison, Loucks, 
Barnes (unpublished notes) varied from 18 1 
