Sexual size dimorphism was analysed in the Red- necked Grebe in southeast Poland. A DNA-based procedure was utilised to sex individuals and to assess the accuracy of morphological criteria for the sex identification of adult breeding birds: discriminant analysis on the sample level and within-pair comparisons. Males were significantly larger than females in all body measurements used in the discriminant function selection process. Owing to considerable overlap in measurements, however, the sexes cannot be accurately separated by biometrics at the population scale. Sexual dimorphism was most pronounced in bill length measured from the corner of the gape to the tip, but only 79% of individuals were correctly identified on the basis of this parameter alone. When two variables, bill length and wing length, were combined, the discriminant function was of similar efficiency (80%) in determining the sex. The accuracy level of sexing may be improved by comparing mates within pairs: combined comparisons of bill length and body mass were as accurate as the genetic technique, but sex assignment was restricted to 76% of the measured pairs.
How to translate text using browser tools
1 December 2006
Sexing Red-Necked Grebes Podiceps grisegena by Molecular Techniques and Morphology
Janusz Kloskowski,
Przemysław Grela,
Jarosław Krogulec,
Gaska Michał,
Marek Tchórzewski
D. G. Ainley
,
L. B. Spear
,
R. C. Wood
1985. Sexual color and size variation in the South Polar Skua. Condor 87: 427–428. Google Scholar
Z. M. Bocheński
1994. The comparative osteology of grebes (Aves: Podicipediformes) and its systematic implications. Acta zool. cracov. 37: 191–346. Google Scholar
A. M. Breault
,
K. M. Cheng
1990. Use of submerged mist nets to capture diving birds. J. Field Ornithol. 61: 328–330. Google Scholar
R. W. Butler
,
A. M. Breault
,
T. M. Sullivan
1990. Measuring animals through a telescope. J. Field Ornithol. 61: 111–114. Google Scholar
R. Casaux
,
A. Baroni
2000. Sexual size dimorphism in the Antarctic Shag. Waterbirds 23: 489–93. Google Scholar
H. Ellegren
,
B. C. Sheldon
1997. New tools for sex identification and the study of sex allocation in birds. Trends Ecol. Evol. 12: 255–259. Google Scholar
D. A. Dawson
,
S. Darby
,
F. M. Hunter
,
A. P. Krupa
,
I. L. Jones
,
T. Burke
2001. A critique of CHD-based molecular sexing protocols illustrated by a Z-chromosome polymorphism detected in auklets. Mol. Ecol. Notes 1: 201–204. Google Scholar
R. S. Ferguson
1980. A technique for live-trapping nesting Horned Grebes. J. Field Ornithol. 51: 179–180. Google Scholar
J. Fjeldså
1973. Territory and the regulation of the population density and recruitment in the horned grebe Podiceps auritus arcticus Boje, 1882. Videns. Meddr Dansk Naturh. Foren. 136: 117–189. Google Scholar
J. Fjeldså
1980. Post mortem changes in measurements of grebes. Bull. Br. Ornithol. Club 100: 151–154. Google Scholar
J. Fjeldså
1983. Ecological character displacement and character release in grebes Podicipedidae. Ibis 125: 463–481. Google Scholar
K. L. Fletcher
,
K. C. Hamer
2003. Sexing terns using biometrics: the advantage of within-pair comparisons. Bird Study 50: 78–83. Google Scholar
R. Griffiths
,
S. Daan
,
C. Dijkstra
1996. Sex identification in birds using two CHD genes. Proc. R. Soc. Lond. B 263: 1251–1256. Google Scholar
J. R. Jehl Jr.
,
P. K. Yochem
1987. A technique for capturing Eared Grebes (Podiceps nigricollis). J. Field Ornithol. 58: 231–233. Google Scholar
P. P. R. Jodice
,
R. B. Lanctot
,
V. A. Gill
,
D. D. Roby
,
S. A. Hatch
2000. Sexing adult Black-legged Kittiwakes by DNA, behavior and morphology. Waterbirds 23: 405–415. Google Scholar
N. W. Kahn
,
J. St. John
,
W. Quinn
1998. Chromosome-specific intron size differences in the avian CHD gene provide an efficient method for sex identification in birds. Auk 115: 1074–1078. Google Scholar
B. E. Lyon
1994. A technique for measuring precocial chicks from photographs. Condor 96: 805–809. Google Scholar
M. L. Mallory
,
M. R. Forbes
2005. Sex discrimination and measurement bias in Northern Fulmars Fulmarus glacialis from the Canadian Arctic. Ardea 93: 25–36. Google Scholar
J. Moreno
1989. Strategies of mass change in breeding birds. Biol. J. Linn. Soc. 37: 297–310. Google Scholar
T. Piersma
1988. Morphological variation in a European population of Great Crested Grebes Podiceps cristatus in relation to age, sex and season. J. Ornithol. 129: 299–316. Google Scholar
B. H. Pugesek
,
K. L. Diem
1990. The relationship between reproduction and survival in known-aged California Gulls. Ecology 71: 811–817. Google Scholar
J. Sambrook
,
E. F. Fritsch
,
T. Maniatis
1989. Molecular cloning: a laboratory manual. Cold Spring Harbor, N.Y. Google Scholar
R. W. Storer
1969. The behavior of the Horned Grebe in spring. Condor 71: 180–205. Google Scholar
B. E. Stout
,
G. L. Nuechterlein
1999. Red-necked Grebe Podiceps grisegena.
In:
A. Poole
,
F. Gill
(eds).
The Birds of North America, No. 465. Philadelphia. Google Scholar
J. A. van Franeker
,
C. J. F. ter Braak
1993. A generalized discriminant for sexing fulmarine petrels from external measurements. Auk 110: 492–502. Google Scholar
K. Weidinger
,
J. A. van Franeker
1998. Applicability of external measurements to sexing of the Cape Petrel at within-pair, within-population and between-population scales. J. Zool. 245: 473–482. Google Scholar

Acta Ornithologica
Vol. 41 • No. 2
December 2006
Vol. 41 • No. 2
December 2006
discriminant function analysis
molecular sexing
Podiceps grisegena
Red-necked Grebe
sexual size dimorphism
within-pair comparisons