BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 277 



The stick nests of the present species were seen everywhere in 

 their range and were of remarkable construction. Thorny twigs 

 were woven in an irregular form, entirely inclosed, with an entrance 

 opening frequently in the form of a short tunnel. These structures 

 were placed in low, often thorny, trees, or occasionally in thistles. 

 It was not unusual to see them built about the wires on the cross 

 arms of telephone and telegraph poles, and occasionally one was 

 built in the head of a railroad semaphore. In one such instance that 

 came under my observation the birds had filled a space between iron 

 uprights 4 feet long and were still busily engaged in carrying sticks 

 up to 10 meters in the air, though lower nesting sites abounded. 

 (PI. 10.) 



On one occasion I observed a pair that had evidently just chosen 

 the site for a new home. The birds had selected a slight opening 

 among more or less horizontal limbs of a thorny tree, where they 

 hopped about a few inches apart as they examined the space criti- 

 cally, or rested near together and pecked and pulled at near-by 

 twigs. At intervals the male sang in a low tone. Nest construction 

 is apparently a prolonged process and the birds seem to work at it 

 when not in breeding condition. As the nests are firmly woven 

 and durable they last for several years. Though ordinarily peace- 

 ful, males fight savagely in defense of their chosen territory, battling 

 with intruders until exhausted. 



The peculiar song of this species, given at times by the female 

 as well as the male, may be represented as chick chick chick chee-ee- 

 ee-ee-ee^ uttered in a rapid monotone, with an effort that shakes the 

 whole body. It is repeated frequently and is often heard from a 

 nest. The call note is a sharp tschick. In the Chaco the guira 

 anumbi of Azara was know^n in Guarani as huituitui in imitation of 

 the song while the Anguete Indians knew it as kas mis ka now ah. 



Tlie development of the skull with age in the Tracheophone meso- 

 myodi seems less rapid than in the Oscines, so that the usual age 

 criterion for our smaller Passeriformes of the extent of cancellation 

 between the plates of the cranium may not be trusted. On March 

 6, 1 killed four Anumbms^ an adult pair and two fully grown imma- 

 ture birds. In the adult male the top of the skull was entirely 

 covered with cancellations. In its mate, an adult female, the top of 

 the skull was still open, as it was in the two young, the offspring of 

 the adult pair. 



An adult male, taken August 23, had the maxilla and tip of 

 mandible cinnamon drab; base of mandible pale drab gray; iris 

 liver brown ; tarsus drab gray ; toes smoke gray. An immature male, 

 taken March 6, had the maxilla and tip of the mandible slightly 

 darker than hair brown ; extreme tip of culmen shading to chaetura 



