590 Yvisconsin Academy of Sciences, Arts, and Letters. 
taken at Glen Lake and Middle Lake is: 3.37x2.25. The 
largest measures 3.50x2.35; the smallest, 3.22x2.13. Eggs 
which have been in the nest some time are generally more or less 
stained and streaked with light brown. 
190. American Bittern. 
Botuurus lentiginosus (Montag.). 
The Bittern, or Bog-pump, as it is appropriately called by 
some, is a common summer bird in the region, and its peculiar 
gutteral chunk-chunk can frequently be heard in the neighbor¬ 
hood of sloughs and swampy places. When flying, the crooked 
position of its neck, forming a hump below, gives it a peculiar 
appearance. Often, when closely approached, the bird stands 
erect with its neck outstretched and bill pointing straight up¬ 
ward. In this position it closely resembles a stick and is fre¬ 
quently mistaken for one. 
The Bittern is retiring in his habits, and for a nesting site 
chooses some lonely place such as the tall grass of a slough, 
bordered by bush willows. Unlike their near relatives, the 
Herons, the Bitterns do not congregate in colonies to breed, but 
the pairs nest singly and the nests are difficult to discover. A 
rather crude affair serves the purpose of a nest. Where the tall 
grass grows thickly in the border of a slough, some of the blades 
are bent down to the water and on these, dead grass is piled. So 
the nest is merely a platform of grass or rushes, only a few 
inches above the water, and with but a slight depression to hold 
the eggs and prevent their rolling offi. A nest of the Bittern is 
shown in Plate XLVIII. Sometimes, when the nest is built 
among rushes, the material used in the construction is rushes. 
Part of the material used in the nest lies in the water and the re¬ 
maining part rests on this foundation. 'Nests observed were in 
water from eight to fourteen inches deep. The nests measure 
from fifteen to nineteen inches outside diameter and the top of 
the nest is from three and one-half to five inches above the surface 
of the water. The bird is a rather late breeder; for nests contain¬ 
ing fresh eggs were taken as late as June 9 and 18. Five was 
the largest number of eggs found in ia nest, while sets of three 
or four were more frequently found. The eggs are drab, with 
perhaps a greenish tint. They are elliptical in shape, some of 
