The bill of the sparrow as an indicator for the male sex hormone. II. Structural basis

Witschi, Emil; Woods, Robert P.

doi:10.1002/jez.1400730305

Cited by 17 publications

(2 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, the signaling function of the bill is still a mystery. Male bill color changes between seasons from a pale horn color in the non-breeding season to a blackish dark color in the breeding season (Witschi and Woods 1936 ), and the color change is due to pigmentation with eumelanins and is known to be mediated by male hormones (testosterone) (Keck 1933 ; Witschi 1936 ; Pfeiffer et al 1944 ; Haase 1975 ; Donham et al 1982 ). Although Václav ( 2006 ) suggested the possibility of an effect of condition on bill color, so far there have been no tests of this.…”

Section: Introductionmentioning

confidence: 99%

Bill color, not badge size, indicates testosterone-related information in house sparrows

Laucht

Kempenaers

Dale

2010

Behav Ecol Sociobiol

View full text Add to dashboard Cite

The honesty of ornamental signals of quality is often argued to be enforced via costs associated with testosterone. It is still poorly understood, however, how seasonal variation of testosterone within individuals is related to the timing and extent of ornament development. Here, we studied inter-and intra-individual variability of plasma testosterone levels in a population of 150 captive male house sparrows (Passer domesticus) through the course of a full year. We further analyzed the relationship between plasma testosterone levels and two sexually dimorphic ornaments: badge size and bill coloration. Also, because of a known negative relation between molt and circulating testosterone levels, we analyzed the relationship between ornamentation and molt status during the fall. We found that testosterone levels increased towards the breeding season and decreased before the onset of annual molt. However, within individuals, relative testosterone titers demonstrated low repeatability between seasons. Plasma testosterone levels were not correlated with badge size in any season but were correlated strongly with bill coloration during all periods, except the breeding season when variation in bill color was low. Finally, we found that bill coloration strongly correlated with molt status during fall. Our results indicate that bill coloration, not badge size, is the best ornamental indicator of a "running average" of male testosterone in house sparrows and therefore the best potential indicator of qualities and/or behavioral strategies associated with testosterone.

show abstract

Section: Introductionmentioning

confidence: 99%

Bill color, not badge size, indicates testosterone-related information in house sparrows

Laucht

Kempenaers

Dale

2010

Behav Ecol Sociobiol

View full text Add to dashboard Cite

show abstract

“…The osteology of the Oystercatcher skull has been described by Kozlova (1961) but few detailed studies have been made on the anatomy of the bill. Clara (1925) and Krogis (193 1) investigated the internal structure of the Woodcock bill (Scolopax rusticola) and Domestic duck bill respectively and Witschi & Woods (1936) made anatomical observations on the bill of the Sparrow (Passer domesticus) to obtain an indication of the level of the male sex hormone. In addition, the functional morphology of the avian bill has been analysed (Bock, 1966) particularly in relation to the external forces acting on the bill during feeding operations.…”

Section: Introductionmentioning

confidence: 99%

Anatomical observations on the bill of the Oystercatcher (Haematopus ostralegus occidentalis) in relation to feeding behaviour

Heppleston

1970

Journal of Zoology

View full text Add to dashboard Cite

Oystercatchers have recently increased as inland breeders in Northern Britain. Concurrently, they have been observed feeding in coastal fields in winter. It is suggested that the bill of this species possesses dual characteristics enabling them to feed on shellfish adn also to probe in the soil for terrestrial invertebrates. The gross internal morphology of the bills of adults and young is described. A bony core contains large nerves running the length of the bill. These break up towards the tip where numerous sensory corpuscles are seen. It is concluded that the possession of a strong bone core together with numerous sense organs at the tip has been of considerable importance in enabling the Oystercatcher to exploit inland situations.

show abstract

The relation of sex hormones to pigmentation and to testis descent in the opossum and ground squirrel

Finkel

1945

Am. J. Anat.

View full text Add to dashboard Cite

The bill of the sparrow as an indicator for the male sex hormone. II. Structural basis

Cited by 17 publications

References 15 publications

Bill color, not badge size, indicates testosterone-related information in house sparrows

Bill color, not badge size, indicates testosterone-related information in house sparrows

Anatomical observations on the bill of the Oystercatcher (Haematopus ostralegus occidentalis) in relation to feeding behaviour

The relation of sex hormones to pigmentation and to testis descent in the opossum and ground squirrel

Contact Info

Product

Resources

About