Fall is the season–after reproduction and before winter losses–when peak numbers of birds are present. Insects, fruits, seeds, etc. have to be abundant to support this horde and allow them to migrate successfully. So, birds are heavily dependent on the weather even before they take off on their marvelous and hazardous journeys. The very fact that they make these journeys allows them to breed and winter in the best possible surroundings and thus maintain their abundance.
Author: Thomas A. Imhof
Volume Number: 18 Year Published: 1970
Issue Number: 3
Page Number: 2
Link to article: http://birdlife.aosbirds.org/1970/Vol 18 No. 3_1970_p2-7.pdf
Link to the full issue of BirdLife: http://birdlife.aosbirds.org/1970/Vol 18 No. 3_1970.pdf