FURNARIUS RUFUS. 169 



roof of a house ; and sometimes, but rarely, on the ground. The 

 material used is mud, with the addition of horsehair or slender fibrous 

 rootlets, which make the structure harder and prevent it from cracking. 

 I have frequently seen a bird, engaged in building, first pick up a thread 

 or hair, then repair to a puddle, where it was worked into a pellet of 

 mud about the size of a filbert, then carried to the nest. When finished 

 the structure is shaped outwardly like a baker's oven, only with a deeper 

 and narrower entrance. It is always placed very conspicuously, and 

 with the entrance facing a building, if one be near, or if at a roadside 

 it looks toward the road; the reason for this being, no doubt, that the 

 bird keeps a cautious eye on the movements of people near it while 

 building, and so leaves the nest opened and unfinished on that side until 

 the last, and there the entrance is necessarily formed. When the 

 structure has assumed the globular form with only a narrow opening, 

 the wall on one side is curved inwards, reaching from the floor to the 

 dome, and at the inner extremity an aperture is left to admit the bird to 

 the interior or second chamber, in which the eggs are laid. A man's hand 

 fits easily into the first or entrance chamber, but cannot be twisted about 

 so as to reach the eggs in the interior cavity, the entrance being so 

 small and high up. The interior is lined with dry soft grass, and five 

 white pear-shaped eggs are laid. The oven is a foot or more in diameter, 

 and is sometimes very massive, weighing eight or nine pounds, and so 

 strong that, unless loosened by the swaying of the branch, it often 

 remains unharmed for two or three years. The birds incubate by turns, 

 and when one returns from the feeding- ground it sings its loud notes, 

 on which the sitting bird rushes forth to join in the joyous chorus, and 

 then flies away, the other taking its place on the eggs. The young are 

 exceedingly garrulous, and when only half-fledged may be heard prac- 

 tising trills and duets in their secure oven, in shrill tremulous voices, 

 which change to the usual hunger-cry of young birds when the parent 

 enters with food. After leaving the nest, the old and young birds live 

 for two or three months together, only one brood being raised in each 

 year. A new oven is built every year, and I have more than once seen 

 a second oven built on the top of the first, when this has been placed 

 very advantageously, as on a projection and against a wall. 



A very curious thing occurred at the estancia house of a neighbour 

 of mine in Buenos Ayres one spring. A pair of Oven-birds built their 

 oven on a beam-end projecting from the wall of a rancho. One morn- 

 ing one of the birds was found caught in a steel trap placed the evening 

 before for rats, and both of its legs were crushed above the knee. On 

 being liberated it flew up to and entered the oven, where it bled to 

 death, no doubt, for it did not come out again. Its mate remained two 



