94' CLASS AVES. 



are no trees, it lays its eggs in holes in the ground. The 

 nest is constructed with nothing but leaves and plenty of 

 horse-hair. The entrance of this nest is so narrow, that it is 

 impossible to draw out the young ones. This swallow is 

 sedentary in Paraguay, rather common, and chirrups much in 

 the spring season. 



The Domestic Swalloio of Paraguay is called by the 

 Guaranis, Mbiyui. This name expresses its cry, which 

 consists in repeating several times the syllables of this word, 

 and they have applied the same name to all the species. It 

 inhabits Paraguay and the river La Plata, and nestles on the 

 cabins and country houses. But in cities and towns it 

 chooses, in preference^ churches and large buildings, where 

 it fixes its nest to the beams or walls, but always in such a 

 manner, that it is scarcely apparent ; sometimes this nest is 

 found imder the tiles. It is said to be composed of clay 

 without and a little straw within. The eggs are three or 

 four in number. This species frequently perches on the 

 crosses of weather-cocks, or the ridges of roofs, and on the 

 barriers of enclosures. During summer, these swallows sleep 

 in the interior of orangeries, or of tufted trees ; but if ever so 

 little cold should occur, they pass the night in holes, or under 

 the tiles. They are birds of passage, but their periods of 

 absence and return are not so strictly regulated as in Europe. 

 They are determined by the greater or less duration of the 

 cold, and consequent abundance of insects ; so that if the 

 winter be mild, they are scarcely two months out of Paraguay, 

 but, in the contrary case, they are absent four months. They 

 pass the winter in the 20th degree of south latitude. 



The Gray Rock-Swalloiv {H. Montana), from Avhich it is 

 probable that H. rupestris ought not to be separated, not- 

 withstanding some little differences of colour, nestles in the 

 Alps, and does not descend into the plains except for the 

 purposes of hunting. Its flight is slower than that of the 

 other species, and it pursues its prey in company with 



