Breeding schedule.—Eggs are laid in every month of the year. The main season of breeding is spring, and this is depicted in Figure 4; the 26 records of breeding by feral birds are from January 11 to June 10, and the modal date of laying is probably April 5.
Number of eggs.—Pigeons usually lay 2 eggs. Nests are of sticks and other plant matter placed on ledges and recesses of buildings, bridges, and cliffs, 10 to 60 feet high.
Fig. 4.—Histograms representing breeding schedules of the Least Tern, two doves, the Yellow-billed Cuckoo, and two owls in Kansas. See legend to Figure 1 for explanation of histograms.
Mourning Dove: Zenaidura macroura marginella (Woodhouse).—This is a common summer resident throughout the State, in open country and woodland edge. The species is also present in winter in much reduced numbers, and many are transient in periods of migration. The time of greatest abundance is from March to November. Doves of extreme eastern Kansas have by some workers been referred to the subspecies Z. m. carolinensis (Linnaeus); specimens at the Museum of Natural History indicate that these doves are best regarded as members of populations of intermediate subspecific, or morphologic, affinities, and that they are satisfactorily included within Z. m. marginella.
Breeding schedule.—Numerous (983) records of egg-laying from north-central Kansas are from April 1 to September 10; the modal date for laying is May 15. Forty-three records of breeding from northeastern Kansas span the period March 21 to August 10; the modal date of laying is May 15. These samples are depicted in Figure 4.
Both sets of data are shown here to illustrate some of the differences between large and small samples of heterogeneous data. The small sample tends to be incomplete both early and late in the season, and the mode tends to be conspicuous. Yet, the modes for the two samples coincide. Also, the data from the north-central sector indicate that egg-laying in March would be found less than once in 983 records, but the small sample from the northeast includes one record for March. Such an instance doubtless reflects, at least in part, the fact that the two geographic sectors have different environmental conditions, but it is likely that the instance also partly reflects the unpredictable nature of sampling.
Number of eggs.—Doves lay two eggs. About one per cent of all nests have 3 eggs, but it is not known for any of these whether one or two females were responsible.
Nests are placed in a wide variety of plants, or on the ground. The commonest plants are those used most frequently; in north-central Kansas one-third of all nests are placed in osage orange trees, but in the northeast elms are most frequently used. Nestsites are from zero to 15 feet high.
Yellow-billed Cuckoo: Coccyzus americanus americanus (Linnaeus).—This is a common summer resident in riparian and second-growth habitats throughout the State. Twenty-three dates of first arrival in spring fall between April 29 and May 22 (the median is May 12), and nine dates of last observation in autumn run from September 13 to October 12 (the median is September 23).