246 BULLETIN 133, UNITED STATES NATIONAL MUSEUM 



planted about wells and water holes miles from larger groves. In 

 eastern Uruguay, where groves of palms cover kilometers of low- 

 land, ovenbirds fairly swarm. There, .though they came familiarly 

 about houses, they are less domestic, as there is abundance of range 

 for them, so that instead of being concentrated near houses they 

 range through the countryside. At San Vicente any alarm was 

 sufficient to bring ten or a dozen to shriek their disapproval of my 

 intrusion. 



The loud calls of the ovenbird never fail to announce its presence. 

 One, presumably the male, with bill thrown up and wings drooped, 

 gives vent to a series of shrieking, laughing calls, with distended, 

 vibrating throat, and quivering wing tips. At about the middle of 

 this strange song its mate chimes in with shrill calls of a different 

 pitch, and the two continue in duet to terminate together. The loud 

 notes may be audible at half a mile. 



Ovenbirds remain paired throughout the year and mated birds 

 may usually be found near one another. Though they s?ek shelter 

 in trees they feed on the ground, frequently far distant from cover, 

 where, with their plump bodies and short tails, they suggest a thrush 

 in form. Search for a livelihood is a serious affair that absorbs 

 every attention, so that they have a preoccupied air. as they walk 

 about in the herbage with nervous hesitant strides and slightly 

 nodding heads. The calls of a neighbor or a mate are certain to 

 bring response even from a distance. 



The strange, domed, mud nest of this bird is certain to attract at- 

 tention from the least observant, as it is built in the most conspicuous 

 situations without the slightest attempt at concealment. Hundreds 

 ntay be seen without effort during travel in the pampas. The usual 

 structure averaged 300 mm. long by 200 mm. wide, though the di- 

 mensions varied according to circumstances, some being nearly 

 globular and others more elongate. A dome-shaped roof with walls 

 25 to 35 mm. thick was elevated on a level mud platform until it was 

 entirely arched over with an irregular hole in one side. An inner 

 wall of curving outline was then constructed leading to the back of 

 the inclosure at one side. This cut off the nest cavity from the en- 

 trance hall, and entry to the nest was througli a small opening, with 

 a raised threshold, below the roof. When the margins of the open- 

 ing were rounded off the structure was complete. As the mud used 

 for building material was mixed with vegetable fibers, grass, or hair, 

 the whole made a structure of great firmness. When mud was 

 scarce the birds sometimes utilized fresh cow dung as building ma- 

 terial, making a structure that when dry, was as strong as a model 

 of papiermache. To examine the interior in any nest it was neces- 

 sary to cut a hole in it with a heavy knife, as the hand could not be 

 introduced into the nest cavity through the entrance. 



