NATURAL HISTORY OF THE SWAINSON'S WARBLER 75 



walker) , which feeds about wet leaf litter and shallow pools and 

 occasionally does some leaf-flipping, in contrast to the shoving 

 aside and "plowing" of the leaf litter by the Swainson*s Warbler. 

 The Swainson's Warbler also obtains some food from the surface 

 of the leaf litter. 



Within a breeding territory, a male usually uses several, per- 

 haps half a dozen, foraging areas on the ground to which it 

 consistently returns. Such areas are usually less than 50 feet 

 square and free of obstructions at and just above ground level. In 

 one Georgia canebrake I observed a male for 30 minutes as it 

 searched for food in one of these special feeding sites measuring 

 20 by 30 feet. 



When foraging in the shrub strata or undergrowth, the Swain- 

 son*s Warbler probes into clusters of dead leaves and the axils of 

 cane plants, as is typical of the Worm-eating Warbler, a species 

 which closely resembles the Swainson's Warbler in size and plu- 

 mage and often occurs in the same place. 



Bill wiping 



After feeding, a Swainson's Warbler mounts a limb and, before 

 preening, spends a number of seconds wiping its bill. Bill wiping 

 presumably is done to remove caterpillar hairs or other insect 

 parts and pieces of dirt. The Swainson's Warbler has a good rea- 

 son to spend more time wiping its bill than most other parulids 

 because of its continuous probing beneath the leaf mantle in moist 

 or wet silty soil. 



FOOD 



A total of 11 Swainson's Warbler stomachs have been examined 

 by biologists of the U. S. Department of the Interior. All were 

 from birds collected in Alabama and Georgia canebrakes. These 

 examinations indicate that the Swainson's Warbler is totally in- 

 sectivorous. Among favorite food items typically occurring be- 

 neath the leaf mantle are crickets (Gryllidae), ground beetles 

 (Carabidae), ants (Formicidae) , and spiders (Arachnidae) . 



Caterpillars (Lepidoptera) occurred in five of six stomachs 

 collected in May and June in Alabama and were the most im- 

 portant by volume in four ; ground beetles were the principal food 

 item in one; and hymenopterous insects (probably ants) were 

 most important in one. Spiders occurred in three of the stomachs. 



The following items, in order of volume, occurred in stomachs 

 of two birds taken at Macon, Ga., in May : ground beetles, cater- 

 pillars, stinkbugs, (Pentatomidae), homopterous insects (Homop- 

 tera), silken fungus beetles (Nitidulidae), and beetle larvae. 



