PRESIDENTIAL ADDRESS SECTION C. 45 



birds are amongst the most obvious enemies, and from what is 

 recorded on the subject, it seems to me that birds are a greater 

 factor in locust suppression in South Africa than they are else- 

 where. Here there are several kinds of birds that follow locust 

 swarms from place to place, and are relatively very scarce or 

 absent altogether in years when there are no swarms. Amongst 

 the most important are two migrants from the northern hemi- 

 sphere, Ciconia alba, here called the large Locust Bird, but in 

 Europe the White Stork, and Glareola mclauoptcra, a pratincole 

 reputed to come from southern Russia and south-western Siberia. 

 Neither of these birds nest in South Africa. They usually arrive 

 in October and November and depart during March, thus being 

 here at the height of the locust season. The studies of German 

 and Hungarian ornithologists have removed any shred of doubt 

 that storks bred in the Baltic region and in Hungary are the 

 storks that reach us. Many individual birds, leg-marked in 

 their northern home with inscribed aluminium rings, have been 

 found in the various ])rovinces of the Union. So highly im- 

 portant do these and congeneric migratory birds appear to be in 

 suppressing a locust outbreak when they become abundant, that 

 one is inclined to think that progressive multiplication of the 

 pest for a series of seasons may be possible only when these 

 birds come to the country in small numbers. Here is another 

 point on w-hich observations are wanted. It seems possible that, 

 as the locust swarms in South Africa become extirpated, the 

 birds gradually cease to come so far south ; and that, when 

 great swarms again develop, the bulk of the birds are several 

 years in discovering the fact. It has to be considered that other 

 parts of Africa are subject to locust visitations, and that to reach 

 this part the birds must traverse the continent from the extreme 

 north-east. May it not be that, when the birds meet w-ith a 

 shortage of locusts here, they flock to some other part where 

 the prey is more abundant, and is there not a remote chance 

 that locust cycles in one region may thereby be made to alternate 

 in a measure with locust cycles in another region? If this 

 address is printed, and meets the eye of observers of locusts in 

 other countries to which our locust birds go. I hope they will 

 be good enough to communicate with me on this subject. And 

 I hope that observers of locust birds in this country may be 

 influenced by mv suggestion to gather data on the relative 

 members of the migrants from year to year. 



There are many other matters in connection with the economy 

 of locusts that I should like to touch upon ; but I feel that I 

 have taken up all the time that I can claim. But I leave the 

 subject much regretting that by my absence I am deprived of 

 discussing it further in private with members of the Association, 

 who might, perchance, be able to give me information that I 

 could turn to advantage. 



