CYCLES OF REPRODUCTION 



can be said is that there is a tendency for the greatest 

 number of eggs to be found in the first 6 months of the 

 year. Just south of the equator the reverse is evident, 

 and as one passes deeper into the southern hemisphere 

 the egg season again becomes more sharply defined 

 until in 50°-6o° S. the optimum month is December. 

 It must be stressed that Fig. i refers to birds in 



II III ly V VI VII VIII IX X x^ u. i ii 



eo'-JO'N 



50-6(rN 

 40-50''N 

 30-40'N 

 20-30n 

 10-20'N 

 0"- KTN 

 0'- 1(fS 

 10'-20'S 

 20-30'S 

 SO'AO'S 



^0-50"S 

 50-60'S 



II III IV V VI VII VIII IX X XI XII I 



Fig. I. — Diagram showing the relative num- 

 bers of times that each month occurs in the 

 records of the egg-seasons in each io° of 

 latitude (after Baker). The months are indi- 

 cated by Roman numerals. 



general, and the conclusion must not be dravs^n that on 

 the equator all birds breed all the time. There are a few 

 records of species which apparently do this, as for ex- 

 ample the birds on the tropical islands of Fernando 

 de Noronha and St. Paul Rocks, i*^ but generally speak- 

 ing each tropical species has a well defined annual 

 breeding season. 

 B 



