Influence of forced renesting and hand-rearing on growth of young captive American Kestrels

1982 ◽  
Vol 60 (1) ◽  
pp. 89-96 ◽  
Author(s):  
David M. Bird ◽  
Paul C. Laguë
Keyword(s):  
Growth Rates ◽  
Sexual Size Dimorphism ◽  
Falco Sparverius ◽  
Tarsus Length ◽  
Size Dimorphism ◽  
American Kestrels ◽  
Body Weights ◽  
Catch Up

During 1974 to 1977, 78 pairs of captive American Kestrels (Falco sparverius) were forced to renest and the hatchlings from the artificially incubated first clutches were hand-reared to fledging age. Sexual size dimorphism, i.e., heavier females, became evident at some undetermined point between the 6th and 12th day of growth. Overall, hand-reared kestrels exhibited significantly slower growth rates and smaller body weights on the 24th day than did parent-raised birds. They did tend to "catch up" to the parent-raised ones, as there were no significant differences later with respect to juvenile and adult weights. Antebrachium and manus length, tarsus length and diameter, and skull width were significantly smaller in hand-reared kestrels.

Female hatchling American kestrels have a larger hippocampus than males: A link with sexual size dimorphism?

2018 ◽  
Vol 349 ◽  
pp. 98-101 ◽  
Author(s):  
Mélanie F. Guigueno ◽  
Natalie K. Karouna-Renier ◽  
Paula F.P. Henry ◽  
Jessica A. Head ◽  
Lisa E. Peters ◽  
...  
Keyword(s):  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
American Kestrels

scholarly journals Sexual Size Dimorphism and Positive Assortative Mating in Alpine Choughs (Pyrrhocorax graculus)

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 553-556 ◽  
Author(s):  
Anne Delestrade
Keyword(s):  
Sample Size ◽  
Assortative Mating ◽  
Body Condition ◽  
Sexual Size Dimorphism ◽  
Morphological Characters ◽  
Positive Trend ◽  
Tarsus Length ◽  
Size Dimorphism ◽  
Positive Assortative Mating ◽  
Larger Sample

Abstract The degree of sexual size dimorphism in a number of different morphological characters was examined in a social corvid, the Alpine Chough, using measurements taken on 178 males and 144 females. A small amount of size dimorphism appeared in all morphological characters, and weight was the most dimorphic character. To identify if Alpine Choughs mate assortatively, measurements of mates were compared in 76 pairs. A positive assortative mating was found on tarsus length, and a small positive trend is suggested between body condition of partners, but that needs to be confirmed with a larger sample size.

Sexual size dimorphism and food requirements of nestling birds

1993 ◽  
Vol 71 (12) ◽  
pp. 2541-2545 ◽  
Author(s):  
David J. Anderson ◽  
Jo Reeve ◽  
Juan E. Martinez Gomez ◽  
Wesley W. Weathers ◽  
Siobhan Hutson ◽  
...  
Keyword(s):  
Gender Difference ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sexual Size Dimorphism ◽  
Positive Association ◽  
Size Dimorphism ◽  
American Kestrels ◽  
Sex Allocation Theory ◽  
Strong Positive Association ◽  
And Gender

The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.

Nestling growth and fledging success in manipulated American kestrel broods

1992 ◽  
Vol 70 (12) ◽  
pp. 2421-2425 ◽  
Author(s):  
Nicholas W. Gard ◽  
David M. Bird
Keyword(s):  
Clutch Size ◽  
Growth Rates ◽  
Brood Size ◽  
Wild Birds ◽  
Falco Sparverius ◽  
Nestling Growth ◽  
American Kestrel ◽  
Fledging Success ◽  
American Kestrels ◽  
Parental Ability

To study factors regulating clutch size in American Kestrels (Falco sparverius), brood manipulation experiments were performed on captive and wild birds in southwestern Quebec during 1986 and 1987. The largest normally occurring brood size was 5 young. Manipulations enlarged or decreased broods to 7 or 2 young, respectively. Significantly more young fledged from wild control and enlarged broods in 1987 than from comparable groups in 1986. The average number of young fledging from enlarged wild broods in 1987 was slightly higher than for control broods, but fledging weight was significantly depressed in enlarged broods. Growth rates and tarsal and antebrachial length at fledging were not affected by brood size, but development of primary feathers was slower in enlarged wild broods. Parental ability to adequately feed all young appears to be the major factor limiting brood size in American Kestrels.

Environmentally determined juvenile growth rates dictate the degree of sexual size dimorphism in the Sardinian brook newt

2014 ◽  
Vol 29 (1) ◽  
pp. 169-184 ◽  
Author(s):  
Claudio Angelini ◽  
Giuseppe Sotgiu ◽  
Giulia Tessa ◽  
Jon Bielby ◽  
Stefano Doglio ◽  
...  
Keyword(s):  
Growth Rates ◽  
Sexual Size Dimorphism ◽  
Juvenile Growth ◽  
Size Dimorphism

scholarly journals Sexual Size Dimorphism and Bohemian Waxwings, Bombycilla garrulus

2009 ◽  
Vol 123 (2) ◽  
pp. 165
Author(s):  
Sarah M. Ludlow
Keyword(s):  
Parental Care ◽  
Sexual Size Dimorphism ◽  
Pectoral Muscle ◽  
Tarsus Length ◽  
Size Dimorphism ◽  
Monogamous Species ◽  
Socially Monogamous ◽  
Energetic Constraints ◽  
Males And Females ◽  
Selection For

Sexual size dimorphism is common among birds, with males generally being larger than females. Sexual size dimorphism is typically more extreme in polygynous species; socially monogamous males are typically only 5% larger than females. However, cryptic sexual size dimorphism has been found in some socially monogamous species. I used standard external measurements as well as two internal measurements (keel length and pectoral muscle mass) to determine whether, or to what extent, Bohemian Waxwings (Bombycilla garrulus) exhibit sexual size dimorphism. Males were only slightly larger than females in all of the characters measured except keel and tarsus length. Keel and tarsus length were 0.6% and 1% longer, respectively, in females than in males. The similar size exhibited by males and females may be related to the amount of parental care provided by males. Smaller body size in males may reflect a trade-off between selection for increased male size and energetic constraints imposed by parental care.

Sexual size dimorphism of walleye (Stizostedion vitreum vitreum)

2003 ◽  
Vol 60 (11) ◽  
pp. 1345-1352 ◽  
Author(s):  
Bryan A Henderson ◽  
Nicholas Collins ◽  
George E Morgan ◽  
Andre Vaillancourt
Keyword(s):  
Growth Rates ◽  
Sexual Size Dimorphism ◽  
Growth Efficiency ◽  
Stizostedion Vitreum ◽  
Relative Importance ◽  
Male Fitness ◽  
Size Dimorphism ◽  
Before And After ◽  
Males And Females ◽  
Epaxial Muscle

Sexual size dimorphism of walleye (Stizostedion vitreum vitreum) is achieved by females having higher growth rates than males before and after maturation, resulting in females with greater asymptotic sizes. Mercury (Hg) concentrations in epaxial muscle by age and weight for 31 populations of walleye were used to evaluate the relative importance of differences in consumption and activity in generating sexual size dimorphism. Growth efficiency by sex, age, and maturity is estimated by a ratio of annual increments in weight (g) to annual increments of Hg (mg), using the pooled changes in weight and Hg loadings of males and females from all lakes. The higher growth rates of females arise from greater consumption and higher growth efficiency. Growth efficiency of both sexes is similar before maturity, but the growth efficiency of mature males is substantially lower than that of either immature males or mature females. We propose that the inferior growth efficiency of males is a function of the greater activity of males, particularly during the spawning season when scramble competition for fertilization is likely to produce substantial increases in male fitness as a result of increased efforts to find and spawn with females.

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