442 THE HOOPOE 



arrival of these birds in Southern Europe. In Southern Spain, Chap- 

 man gives May 1st as the average nesting time, and this accords fairly 

 well with my own observations, though full clutches may be found in 

 the last week of April. On April 28, 1907, however, I came across a 

 hoopoe's nest in a willow in Central Spain, not far from Madrid, where 

 the birds might well be expected to be later breeders than in the 

 Andalucian plains. On cutting this nest out, to my astonishment I 

 found big young, with well-developed crests and primaries, so that 

 even on this plateau some birds must have eggs at the beginning 

 of April. In Middle Europe the best time for full clutches is about 

 the second or third week in May, and in Asia Minor also about the 

 same time. 



While the hen is sitting the cock keeps watch in the neighbour- 

 hood, and warns her of the approach of danger by a harsh chattering 

 note. This sound is also heard when two birds are quarrelling. 

 Another curious note which is not unfrequently uttered is a curious 

 cat-like " quuaauw " or " kiaouww" I have never been able to get 

 a good view of the bird when making this noise, but while the familiar 

 "poo-poo-poo" is being uttered the bird bows its head (with de- 

 pressed crest) to the branch on which it sits, and even at a distance 

 one can see that the neck is inflated. The sound also varies, some- 

 times being quite softly uttered, and at other times more loudly. 

 Swinhoe sent some interesting notes to the Zoologist (1858, p. 6229) 

 on the method in which this sound is produced. He states there that 

 the air is drawn into the trachea, which puffs out on each side of the 

 neck, and is then forced out again by striking the point of the bill 

 against the ground, each stroke producing a separate and distinct 

 note. At the end of the three notes which make up its song, the air 

 is exhausted, and before repeating its call the neck is re-inflated with 

 a slight gurgling noise. In some further notes on the same subject 

 in the Proc. Zool. Society of London, 1871, p. 348, he points out that the 

 trachea of the hoopoe is not dilatable, but its oesophagus is, and the 

 puffing of the neck is caused by the bulging of the oesophagus with 



