The Number of Contour Feathers in Passeriform and Related Birds

Abstract

WHILE studies of the arrangement of the contour feathers of birds on the body (pterylosis) have been numerous only slight attention has been given the total number of feathers comprising the plumage so far as I have been able ascertain. Dr. Jonathan Dwight' found 3235 feathers on a male Bobolink taken in spring. R. C. McGregor2 has recorded 1899 feathers on a Savannah Sparrow (presumably a western form) and 6544 on a Glaucouswinged Gull both enumerations being made from study skins. Miss Phoebe Knappen3 has reported 11,903 feathers on an adult female Mallard obtained March 19, 1932 at Pohick, Virginia, the bird being one that had died from phosphorus poisoning. According the legend on a cartoon in the 'American Magazine' for October, 1934, p. 86, to settle an argument over the number of feathers on the average chicken, Vernon Thornburg, Barnesville, Ohio, dairy employee, killed and plucked a Plymouth Rock. He reported 8,325 feathers. The only other report of pertinence known me is that of Dr. Percy Lowe4 who records that in a young of the Gentoo Penguin (Pygoscelis papua) he found 300 feathers the square inch. The total number for the bird was not given. No other notes on this subject have come my attention. Though the number of feathers that might compose the plumage of the average bird had been in mind as a subject worthy of thought for a number of years it was not until 1933 that opportunity came make definite investigation. Through funds provided by a grant from the private income of the Smithsonian Institution it was possible then carry out a series of studies that covered the period from the middle of February the end of October with an intermission from the middle of July the latter part of September when it was not practicable secure birds that were not in molt. The actual labor of counting was done under my direct supervision by Marie Siebrecht (now Mrs. James Montroy) who, employed as an assistant, worked carefully and conscientiously at a long and somewhat tedious task. A brief report on this work was given before the A. 0. U. meeting in New York City in the fall of 1933, and it was intended continue the investigation. Various circumstances have prevented this and it seems desirable now place the observations made on record.