@article{oai:nipr.repo.nii.ac.jp:00002044,
 author = {Tanaka,Hiroyuki and Ogi,Haruo},
 journal = {Memoirs of National Institute of Polar Research. Special issue},
 month = {Dec},
 note = {P(論文), Tufted Puffins (Lunda cirrhata) were divided into six stages (F(Y), F(0)-F(4)) according to the number of bill furrows formed in the reddish outer part of the upper bill. To clarify the morphological difference between sexes and among stages, eleven morphological measurements of the bills were made. Males were significantly larger than females in most of the measurements. For example, if Tufted Puffins had a gape length longer than 44.0mm there was a 72.5 percent chance that these birds would be male. The variations of these measurements among the six stages of bill furrows were recognized to have three patterns; two measurements along the gape did not vary despite the stages, five measurements, two of which were connected with lower bill, found to be changed between F(Y) and F(0), and four measurements in terms of upper bill were found to be altered between F(Y) and F(0), and F(2) and F(3). The number of bill furrows of the Tufted Puffin corresponded to six age groups on the analogy of the relationship reported between the number of bill furrows and the age in the Atlantic Puffin (Fratercula arctica) (A. PETERSEN : Ornis Scand., 7,185,1976; M. P. HARRIS : Br. Birds, 74,246,1981). The bill furrows of F(Y), F(0), F(1), F(2), and F(3) and F(4) would correspond to the age of 0 to 1,1 to 2,2 to 3,3 to 4,and 5 or older, respectively.},
 pages = {160--166},
 title = {Evaluation of bill furrows as age indicator in the Tufted Puffin Lunda cirrhata},
 volume = {44},
 year = {1986}
}