5 68 



THE QUARTERLY REVIEW OF BIOLOGY 



going around the countryside, inspecting 

 various kinds of nests, making notes of 

 the dietetics of the different species, and 

 then repairing to its favorite perch to 

 cogitate upon its researches and finally 

 decide to limit itself to any one of them. 

 Specificities must have originated without 

 premeditation and survived because they 

 were convenient. The fact that not all 

 parasitic cuckoos are specific indicates 

 that some never went through any such 

 experience as the didric cuckoo is subject 

 to. Host-specificity is decidedly con- 

 venient to a didric cuckoo fortunate 

 enough to have within its territory a 

 whole colony of suitable nests. Their 

 territorial instincts of defense, like those 

 of most parasitic species, are faulty and 

 if they had to wander far afield in their 

 search for nests the chances are they would 

 not be able to keep any territory for 

 themselves. That is what seems to have 



taken place in the Indian Koel, Eudynamis 

 honor at a. In this species individual terri- 

 tories as such seem non-existent any more. 

 Baker (5) writes that the koel, " . . . . 

 sets all Cuckoo laws in defiance; many 

 birds breed in the same area and even in 

 the same tree; and as many as eleven have 

 been taken together." 



The important point in all this for our 

 immediate purpose is that the development 

 of host specificities seems to depend on the 

 strict adherence to individual breeding 

 areas. This indicates that with the 

 development of the parasitic habit in the 

 cuckoos there was no coincidental diminu- 

 tion of the reality of the territory such as 

 we find in the cowbirds. 



The evolution of the habit in different 

 groups of birds in widely separated parts 

 of the world is one of the most notable 

 examples of parallel development in the 

 great group of birds. 



LIST OF LITERATURE 



(1) Allen, Glover M. 1915. Birds and Their 



Attributes, pp. 198-2.16. 

 (2.) Audubon, John James. 1842.. Birds of 



America, iv, pp. 18-zz. 

 (3) Baker, E. C. Stuart. 1907. The oology of 



Indian parasitic cuckoos, pts. 1, i, 3. Journ. 



Bombay Nat. Hist. Soc, xvii, pp. 71-83, 



351-374, 678-696. 

 (4) . 1913. The evolution of adaptation in 



parasitic cuckoos' eggs. Ibis, 10th series, 



vol. i, no. 3, pp. 384-398. 

 (5) . 1911. Cuckoos; some theories about 



the birds and their eggs. Bull. Brit. Orn. 



CI., eclxvii, vol. xlii, pp. 93-112.. 

 (6) . 192.3. Cuckoos' eggs and evolution. 



Proc. Zool. Soc. Lond., no. xix, pp. 2.77-2.95. 



(7) Baldamus, E. 1853. Ncue Beitrage zur Fort- 



pflanzungsgeschichte des europaischen Ku- 

 ckuks. Naumania, iii, p. 307. 



(8) Barrett, C. L. 1906. The origin and develop- 



ment of the parasitical habits in Cuculidae. 

 Emu, vi, pp. 55-60. 



(9) Barrows, W. B. 1883. Birds of the lower 



Uruguay. Bull. Nut. Orn. CI., viii, pp. 133- 

 *34- 



(10) Bendire, Charles E. 1893. The cowbirds. 



Rep. U. S. Nat. Museum, pp. 587-62.4. 

 (n) Chance, Edgar P. 1916. Observations on 



the cuckoo. Brit. Birds, xii, no. 8, pp. 182.- 



184. 

 (12.) . 1919. Observations on the cuckoo. 



Brit. Birds, xiii, no. 4, pp. 90-95. 

 (13) . 1911. The Cuckoo's Secret. 



(14) Coubs, Elliott. 1874. Birds of the North- 



west: a handbook of the ornithology of the 

 region drained by the Missouri River and its 

 tributaries. Dept. of the Interior, U. S. Geol. 

 Surv. Terr. Misc. Publ. no. 3, pp. 164, 180-186. 



(15) Craig, W. 1913. The stimulus and the inhibi- 



tion of ovulation in birds and mammals. 

 Journ. Animal Behavior, iii, no. 3, pp. 2.15 — 



2.11. 



(16) Evans, A. H. 1912.. Notes on the life history 



of Cuculus canorus, with exhibition of eggs. 

 Proc. Zool. Soc. Lond., pt. 1, pp. 197-199. 



(17) Friedmann, Herbert. 192.5. Notes on the 



birds observed in the lower Rio Grande valley 

 of Texas during May 1914. Auk, xlii, no. 4, 



PP- 537-554- 



(18) . 192.7. Testicular asymmetry and sex 



