16 INTRODUCTION. 
are the Pewees, swallows, and those birds who lay their eggs 
in holes. The second set of eggs usually appears from four to 
six weeks after the first, if that has not met with serious mis- 
haps; otherwise, sooner. If a hawk’s nest be robbed,!% the 
parents commonly repair an old nest near by, often hastily 
lining it with evergreen or the like, and at the end of about 
a fortnight two or three eggs are laid. The Sharp-shinned 
Hawks, Kingfishers, Golden-winged Woodpeckers, and very 
probably other species, are said to continue sometimes for several 
days to lay eggs almost daily, after the first sets have been 
taken, though continually robbed. Smaller birds have been 
known to build a second, and even a third nest, within a few 
feet of the previous ones, when these were removed. 
They have also been known to cover the eggs of a Cow-bird, 
by building a second story, or even a third, which became 
their own nursery. Such cases are, however, exceptional, and 
lead me to speak of desertion. 
§ P. Birds differ widely in respect to desertion, the wood- 
peckers, especially the Golden-winged, being in case of disturb- 
ance uncertain in their movements. The latter often leave 
forever the excavation, on which they are at work, if they 
imagine that they are watched, though occasionally regardless 
of those passing by. If their eggs be disturbed, they some- 
times ‘‘ desert,” and at other times the female continues to lay 
eggs in the manner already described. She often deepens her 
nest, and lays a second set. A general rule is that birds will 
not desert their nests (if not injured) when one egg is taken 
from three or four, two from five or six, and three from more 
than six. Never handle a nest or eggs, not to be at once 
13 Unless that of a Marsh (or Sparrow ?) Hawk. 
