8 ILLINOILS* AUDUBON BULL 
The Role of Songbirds in Agricultural Pest Management: 
A Need for Authentication 
By LOWELL L. GETZ 
Vivarium Building 
University of Illinois 
Champaign, Illinois 61820 
One of the current concerns of environmentalists is that of environmen- 
tal contamination from the use of chemical pesticides, including herbicides 
and insecticides. Such contamination is especially serious in agricultural 
regions where present pest management programs depend primarily on the 
use of chemical agents. As this concern evolves into demands for action to 
restrict the use of chemical pesticides, there will be a necessity to develop 
alternative management programs to control pest species of plants and in- 
sects. Such programs should make maximum use of natural control agents. 
Songbirds have long been considered an important factor in the control 
of noxious insects and weeds. Unfortunately insufficient studies have been 
made to permit an accurate evaluation of the impact of songbirds on agri- 
cultural pests in North America. Although songbirds consume large quan- 
tities of insects, especially during the breeding season, the degree of utiliza- 
tion of agricultural pest species is not known. Food consumption during the 
nonbreeding season is less known; many species consume seeds at these 
times, but again it is not known that they eat pest weed seeds. 
Clean farming practices, such as are now prevalent in central Illinois, 
have eliminated much of the natural habitat of songsbirds. As a result, many 
species are now relatively rare in agricultural regions. Therefore even if 
a species were potentially beneficial in regard to the control of agricultural 
pests, practical means would have to be found to increase its numbers before 
there would be a significant contribution to the control of pest species. 
There are several critical factors that must be known before one can 
assess the potential of songbirds in the control of agricultural pests. These 
include: 
1. Seasonal feeding habits, to include precise information as to the 
species of insects and weed seeds eaten, as well as the quantities 
of each. 
2: Habitat requirements, especially preferred vegetation types and 
ability to utilize linear habitats such as fencerows and roadsides. 
3. Foraging ranges of individual birds; i.e., do the birds feed only in 
the fencerows and roadsides, or do they also feed out into the 
adjacent fields? 
4. Maximum population densities that can be attained in given linear 
habitats. 
If the above information were known, it would be possible to determine 
maximum consumption of agricultural pests (insects and weed seeds) that 
could be expected from given species of songbirds per unit area of non- 
agricultural habitat. The foraging data would indicate the spatial pattern 
of the fencerows and roadsides required to afford complete coverage of the 
intervening cultivated fields. When the consumption data are compared 
with the total pest insect populations and weed seed production in given 
crop types, one could predict the maximum pest control that could be 
attained from songbirds. 
