186 
FRANCIS H. HERRICK 
4. HABITS OF CUCULUS CANORUS AND THE BLACK-BILLED 
CUCKOO COMPARED 
For a better comparison of the European and American 
cuckoos, some of the significant facts in their life-histories are 
here presented in parallel columns, further details on the habits 
and behavior of the American species being given in the follow- 
ing sections. 
CUCULUS CANORUP 
COCCYGU8 ERTTHROPHTHALMUS 
10. 
11. 
12. 
13. 
The same 
11.83 in. 
Migration: Spring order: males The same, 
precede females by about a week; 
fall order: adults, followed by the 
young. 
Nocturnal habits: Migrate at night 
and frequently active and calling 
all night. 
Length of adult: 12 in. 
Weight of female: 4| oz. 
Size of egg: Extremes, 24-20 X 29.27-22.35 X 22.86 - 18.54 mm; 
17.4-15.7 mm; 
average, 22 X 16.5 mm. 
0.87 X 0.68 in. 
Weight of egg: 4-5 g. 
Ratio of body-weight to egg-weight 
33: 1. 
Egg-shell: Hard and thick. 
Color of egg: Variable. 
27.23 X 20.53 mm. 
1.07 X 0.81 in. 
6.84 g. 
Number of eggs: 6 or more (doubt- 
ful). 
Succession of eggs: At intervals 
of 6-7 days (Baldamus). 
Incubation: 2 weeks, or less; by 
nurses. 
Nest: Stolen; egg either laid in 
nest of a nurse, or on the ground 
and carried to a nest in bill. The 
same cuckoo lays but a single egg 
in the same nest, and it often re- 
sembles the eggs of the foster-par- 
ents in size and color. 
Thin and fragile. 
Light blue; but rarely mottled or mar- 
bled. 
2-7 to the litter, and possibly two lit- 
ters. 
Irregular; daily, or more commonly 
every other day. 
2 weeks ( ? ) ; by both parents. 
Built in the form of a saucer-shaped 
platform of twigs and leaves; well 
protected and concealed. Eggs 
sometimes laid in another bird's 
nest, or removed in bill to another 
nest of their own, when the first 
has been disturbed. 
