102 THE STORY OF THE BIRDS. 
tribution, habits, colors, ete., show themselves to be 
of Southern origin, building up North here light, airy, 
basketlike, saucer-shaped nests, like those their ances- 
tors were cradled in under the equator. Some swal- 
lows, however, evidently from the South, use feathers. 

European house swallow. 
Some southern birds’ eggs, as noted in the last 
chapter, require less heat to hatch them than those of 
their hothouse friends. And here is the crested fly- 
