338 MICHIGAN BIRD LIFE. 
it is not possible to generalize safely in regard to either species. They 
seem to arrive from the south at about the same time, which is early in May 
in the southern part of the state and from five to ten days later in the 
Upper Peninsula. Average dates for Detroit and Lansing will range from 
May 10th to 20th. 
This is one of the birds whose voice is often heard at night and its usual 
call, coo-coo-coo, or kuk-kuk-kuk, is common to both species and is familiar 
to most outdoor people. Both the cuckoos have numerous variations 
of this call, and several entirely distinct notes, but our best observers are 
unwilling to assign any one of these notes exclusively to either species, 
and we know of no characteristic note belonging to the Yellow-billed Cuckoo. 
Nest building begins ordinarily in June, but not commonly until the 
middle of the month or even later. According to Bendire ‘“ In the northern 
part of its range the breeding season is at its height during the latter part 
of June and the first week of July, and here one brood only is reared, while 
in the south they sometimes raise two.”’ The nest is a very simple affair, 
consisting of a little platform of twigs, leaf-stems, and perhaps a few catkins, 
slightly hollowed to receive the eggs, and lodged rather than placed in the 
crotch of a bush, among a tangle of vines, or sometimes on the horizontal 
spreading branch of an evergreen. Not infrequently the old nest of some 
other bird is used with only slight repairs or additions. The eggs are three to 
five, pale blue, often more or less nest-stained, and always unspotted, though 
frequently clouded or “‘water-marked” in a manner which is easily recog- 
nized but not readily described. They average 1.21 by .88 inches. 
It seems to be a fact that the two species of cuckoos not infrequently 
lay their eggs in each others nests, and this by many is considered a relic 
of the parasitic habit so strongly developed in the old world cuckoos, which 
usually build no nests of their own, but impose the care of their eggs and 
young on other and mostly smaller birds. Single cuckoos eggs are not 
infrequently found in the nests of other birds here in Michigan, but not 
more often perhaps than we find eggs of the Robin, blackbirds and some 
sparrows. In this connection it should be noted that comparatively fresh 
eggs and newly hatched young are sometimes found in the same nest, 
although as a general rule the set is completed before incubation begins. 
It is difficult to believe that only one brood is reared in Michigan each season, 
since eggs are common in June and all through July and August, even a few 
sets being found in September. It is possible that these are merely second 
layings by birds which have been unfortunate with their first nests, but it 
seems much more likely that many individuals rear two broods 
The food of this cuckoo consists very largely of insects, and probably 
we have no bird which is more valuable to the orchardist and fruit grower. 
The careful studies made by the Department of Agriculture at Washington 
have shown that more than 75 percent of the food consists of insects, and 
these are almost all of injurious kinds. It is particularly fond of cater- 
pillars and appears to delight in those forms which are covered with hairs 
and spines. It isa common thing to see a cuckoo perch near a nest of tent 
caterpillars (Clistocampa), and quietly swallow one caterpillar after another 
until seven or eight have been taken, then rest for half a minute or more 
before eating an equal number, repeating this action several times until 
the appetite is satisfied or the supply of caterpillars exhausted. In several 
instances more than one hundred tent caterpillars have been taken from 
a single cuckoo’s stomach, and the bird is almost equally destructive to 
various other hairy caterpillars. Even those caterpillars which are covered 
