244 -^'^^ World-Evidence . 



while the females perched near by, without seeming 

 enthusiastic, take it much as a matter of course, 

 listening at times it may be, but as likely preening 

 their plumage with other thoughts and an ulterior 

 purpose. The performance over, a very little while 

 afterward the whole band goes trooping after food to 

 the nearest cattle-yard or pasture." 



In how far, as suggested already, may the same 

 causes account for the great disproportion in numbers 

 of the sexes of our common cuckoo ? Has hardness 

 and weight of the shell here, as there, a great deal to 

 do with it ? Were Mr. Bidwell's highest weight eggs 

 those of males, and the lowest weight eggs those of 

 females ? 



V. Mr. Hudson, speaking of the Molothrus honar- 

 iensis, says : 



" It continues in better condition than other spe- 

 cies, not having been engaged in the exhausting 

 process of rearing its own young, and, moreover, 

 being gregarious and practising promiscuous sexual 

 intercourse, must lay a much greater number of eggs 

 than other species." Hens that never become broody 

 lay a great deal more than others. In wild districts, 

 where the parasitic instinct was formed, and where 

 birds building accessible nests are proportionately fewer, 

 the instinct seems different from what it does i)i cid- 

 tivated districts. Parasitical eggs are not common in 

 the desert, and even the most exposed nests are prob- 

 ably never over-burdened with them. But in cul- 

 tivated places, where their food abounds, the birds 

 congregate in the orchards and plantations in great 

 numbers, and avail themselves of all the nests — ill- 



* P. 277. 



