(1453) Cuculus canorus bakeri Hartert.
The Khasia Hills Cuckoo.
Cuculus canorus bakeri, Fauna B. I., Birds, 2nd ed, vol. iv, p. 139.
This is a more or less sedentary race of the European Cuckoo, first recorded from the Khasia Hills, whore, literally, it swarms. Thence it extends throughout the Burmese hills to the Shan States and Karenni. South it occur a in the Pegu Yomas and East it extends to Yunnan. It is a bird of comparatively low elevations. In Assam it breeds principally between 4,000 and 6,000 fect, and I have seldom found it below the former. In Burma and the Shan States it, however, often breeds considerably lower, and many eggs have been taken at 3,000 feet.
I have seen several thousand eggs of this Cuckoo, and it is un¬doubtedly the species, or subspecies, on which one can most easily base and thus prove or disprove one’s theories. For the present I content myself with repeating the information given in the ‘Fauna.’ The principal fosterers over a great part of the range of this Cuckoo are birds of the genera Cisticola and Suya and, in the Khasia Hills, nine Cuckoo’s eggs out of every ten, perhaps even a greater proportion than this, are deposited in the nests of these little birds. Both genera make small fragile nests of grass, domed, with a small entrance on one side and generally built on slender grasses. No Cuckoo could deposit its eggs in these nests in the normal manner, and the young Cuckoo, when hatched, distends the nest as it grows, until it either bursts or the grasses break under the weight and it falls to the ground. Normal Cuckoo’s eggs deposited in these nests agree fairly well with those of the fosterers except in size. Inter¬mediate eggs are common, which are less like the eggs of either species but which yet agree with slightly aberrant types of one or the other fosterer. In the Northern Burmese hills the favourite fosterers are the various Chats, and here a blue egg of the Cuckoo’s is constantly found in the nest of Oreicola ferrea haringtoni, which also lays blue eggs. Many Cuckoos also are parasitic on birds of the genera Monticola (Petrophila), Niltava, Muscisylvia etc., all of which lay more or less salmon-coloured eggs, and we find that the Cuckoo’s eggs are very similar to those.
In the Khasia Hills I have taken many blue eggs of Cuckoos from the nests of Leiothrix and Mesia, both of which genera lay blue eggs boldly marked with spots of deep reddish. Eggs may occasion¬ally be placed in the nests of almost any kind of bird in almost any kind of position. Thus I have found eggs twice in the nests of the tiny Warbler Abrornis placed in small upright bamboos with an entrance nothing like an inch in diameter, the bamboos so small that the young Cuckoo when hatched could not have survived many days.
The period of incubation seems to vary greatly, A nest of Cisticola cursitans which contained three eggs on the 10th May when visited on the evening of the 27th had three Warbler chicks and a young Cuckoo just emerging from the shell. Another egg laid in a Pipit’s nest on the 14th May did not hatch until the 28th of that month.
Cuckoos have very definite breeding areas, often very restricted in size, sometimes of great extent, but they certainly leave these and continue laying elsewhere when the foster possibilities of the first are exhausted.
The breeding season commences in the middle or end of April and continues throughout May and June, and in lessening numbers in July, a few birds even laying as late as August.
As regards the number of eggs laid by an individual Cuckoo, I have taken seventeen eggs of the same Cuckoo in one season (1932) and another series of fifteen and several of about twelve but, of course, one cannot guarantee that every egg has been found.
Three hundred eggs average 24.2 x 17.0 mm. : maxima 26.9 x 18.3 and 25.4 x 19.3 mm. ; minima 21.0 x 17.1 and 22.4 x 16.2 mm.
The almost invariable shape is a broad blunt oval and the texture is similar to that of the egg of the European Cuckoo.
1453. Cuculus canorus bakeri
(1453) Cuculus canorus bakeri Hartert.