Higher reversed sexual size dimorphism among nesting pairs of Northern Pygmy-Owls (Glaucidium gnoma) in northwestern Oregon than among specimens collected at the range-wide scale

2021 ◽  
Vol 132 (3) ◽  
Author(s):  
John F. Deshler
Keyword(s):  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Wide Scale ◽  
Glaucidium Gnoma ◽  
Reversed Sexual Size Dimorphism

scholarly journals Why female birds of prey are larger than males

2020 ◽  
Vol 129 (3) ◽  
pp. 532-542
Author(s):  
Jonny Schoenjahn ◽  
Chris R Pavey ◽  
Gimme H Walter
Keyword(s):  
Sexual Size Dimorphism ◽  
A Priori ◽  
Nest Defence ◽  
Birds Of Prey ◽  
Causal Process ◽  
Size Dimorphism ◽  
Substantial Body ◽  
Key Factor ◽  
Reversed Sexual Size Dimorphism ◽  
Passionate Debate

Abstract The causes of the reversed sexual size dimorphism (RSD; females larger than males) in birds of prey are subject to a centuries-old, passionate debate. A crucial difficulty is to distinguish whether the postulated benefits derive from the proposed causal process(es) or are incidental. After reviewing the existing literature, we present a methodology that overcomes this difficulty and renders unnecessary any speculative a priori distinctions between evolved function and incidental effects. We can thus justify the following novel version of the well-known nest defence hypothesis as the most likely to explain the phenomenon in all birds of prey that show RSD: if the female predominates in actively defending the eggs and young against predators, then she is the heavier sex, and her relatively greater body mass is adaptive. That is, heavier females are favoured (independently of males) by natural selection. The attractiveness of this hypothesis is that it has the potential to explain the phenomenon in all raptors exhibiting RSD, can deal with the exceptional cases in this group, explains the direction of the dimorphism, focuses on a key factor in the reproductive success of most raptors, is parsimonious, i.e. does not require supporting hypotheses, and is supported by a substantial body of evidence.

scholarly journals Reversed sexual size dimorphism: body size patterns in sexes of lesser kestrels (Falco naumanni) in the Ikh Nart Nature Reserve, Mongolia

2019 ◽  
Vol 12 (3) ◽  
pp. 363-368 ◽  
Author(s):  
Onolragchaa Ganbold ◽  
Richard P. Reading ◽  
Ganchimeg J. Wingard ◽  
Woon Kee Paek ◽  
Purevsuren Tsolmonjav ◽  
...  
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Nature Reserve ◽  
Size Dimorphism ◽  
Falco Naumanni ◽  
Reversed Sexual Size Dimorphism

scholarly journals Structural complexity of hunting habitat and territoriality increase the reversed sexual size dimorphism in diurnal raptors

2018 ◽  
Vol 49 (10) ◽  
pp. e01745 ◽  
Author(s):  
Lorenzo Pérez-Camacho ◽  
Sara Martínez-Hesterkamp ◽  
Salvador Rebollo ◽  
Gonzalo García-Salgado ◽  
Ignacio Morales-Castilla
Keyword(s):  
Sexual Size Dimorphism ◽  
Structural Complexity ◽  
Size Dimorphism ◽  
Reversed Sexual Size Dimorphism

Evolution of Reversed Sexual Size Dimorphism in Skuas and Jaegers

The Auk ◽  
1999 ◽  
Vol 116 (1) ◽  
pp. 158-168 ◽  
Author(s):  
Paulo Catry ◽  
Richard A. Phillips ◽  
Robert W. Furness
Keyword(s):  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Reversed Sexual Size Dimorphism
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