BIRD BANDING LINCOLN 341 



cycle on population density and scarcity among various forms of 

 life has received much attention from some biologists. According to 

 the theory of Julian Huxley (1927) meteorological conditions of the 

 earth which are caused periodically by sun-spot maxima result in 

 conditions favorable for increased productivity of plant life, and, 

 therefore, of herbivorous animals and their predators. Epidemic 

 disease then causes numerical reduction to the minimum when the 

 cycle is repeated. It has been found that the average length of 

 this cycle is either a little more than 11 years, or else is one-third of 

 this, and Mrs. Gillespie finds in her data a striking suggestion of a 

 4-year cycle for abundance in the tufted titmouse. In the words 

 of Mrs. Gillespie : " The results of 12 years' observations show a 

 tendency toward alternate years of presence and absence about the 

 banding station or near vicinity; and a peak of population density 

 every four years, followed by a scarcity of numbers." 



The song sparrow {Melospiza tnelodia) is not only one of the most 

 widely distributed of our native birds, but also one of the sweetest 

 singers. Added to these qualities is its general willingness to as- 

 sociate with human habitations. Taking advantage of a local con- 

 centration of this species, Mrs. Margaret Morse Nice (1930, 1931, and 

 1932) has conducted a most interesting and important investigation 

 at Columbus, Ohio. 



In the region under consideration the song sparrow attempts to 

 raise three broods, sometimes producing a fourth set of eggs if one 

 or more nests meet with disaster. During the incubation period the 

 average routine for the female is between 20 and 30 minutes on the 

 eggs, alternated with feeding periods of 7 to 9 minutes. There does 

 not appear to be any set time, however, as either period may be 

 longer or shorter. 



One of the features of this study has been a careful investigation 

 of the territory requirements and its occupation. In the vicinity of 

 Columbus it was found that about half of the males are permanent 

 residents which appear to spend their entire adult lives within the 

 space of a few acres. These birds might be said to guard their nest- 

 ing territory throughout the year, although there seems to be no 

 exhibition of this other than in the breeding season. The other 

 males and females move southward for the winter, but are likely 

 to return to their territory of the preceding season, which is then 

 occupied for six or eight months. In the conduct of its nesting 

 duties, the song sparrow apparently requires about two-thirds of an 

 acre and does not usually occupy more during one nesting. In 1931, 

 however, several banded males that returned to their territories, were 

 observed to spread out to some extent and include larger areas in 

 their domains. A reduced number of birds was the apparent answer 



