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Testosterone and Year-Round Territorial Aggression in a Tropical Bird

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HAU, Michaela, Martin WIKELSKI, Kiran K. SOMA, John C. WINGFIELD, 2000. Testosterone and Year-Round Territorial Aggression in a Tropical Bird. In: General and Comparative Endocrinology. 117(1), pp. 20-33. ISSN 0016-6480. eISSN 1095-6840. Available under: doi: 10.1006/gcen.1999.7390

@article{Hau2000-01Testo-42526, title={Testosterone and Year-Round Territorial Aggression in a Tropical Bird}, year={2000}, doi={10.1006/gcen.1999.7390}, number={1}, volume={117}, issn={0016-6480}, journal={General and Comparative Endocrinology}, pages={20--33}, author={Hau, Michaela and Wikelski, Martin and Soma, Kiran K. and Wingfield, John C.} }

<rdf:RDF xmlns:dcterms="" xmlns:dc="" xmlns:rdf="" xmlns:bibo="" xmlns:dspace="" xmlns:foaf="" xmlns:void="" xmlns:xsd="" > <rdf:Description rdf:about=""> <bibo:uri rdf:resource=""/> <void:sparqlEndpoint rdf:resource="http://localhost/fuseki/dspace/sparql"/> <dc:creator>Wikelski, Martin</dc:creator> <dc:date rdf:datatype="">2018-06-11T11:48:54Z</dc:date> <dcterms:issued>2000-01</dcterms:issued> <dc:contributor>Hau, Michaela</dc:contributor> <foaf:homepage rdf:resource="http://localhost:8080/jspui"/> <dc:language>eng</dc:language> <dc:contributor>Wikelski, Martin</dc:contributor> <dc:contributor>Soma, Kiran K.</dc:contributor> <dcterms:available rdf:datatype="">2018-06-11T11:48:54Z</dcterms:available> <dcterms:isPartOf rdf:resource=""/> <dc:creator>Hau, Michaela</dc:creator> <dcterms:title>Testosterone and Year-Round Territorial Aggression in a Tropical Bird</dcterms:title> <dc:creator>Soma, Kiran K.</dc:creator> <dc:creator>Wingfield, John C.</dc:creator> <dc:contributor>Wingfield, John C.</dc:contributor> <dspace:isPartOfCollection rdf:resource=""/> <dcterms:abstract xml:lang="eng">Testosterone (T) regulates avian behaviors such as song and aggression during the breeding season. However, the role of T in year-round territorial birds is still enigmatic, especially in tropical birds. Spotted antbirds (Hylophylax n. naevioides) defend territories in the Panamanian rainforest year-round but have low plasma T levels (0.1-0.2 ng/ml), except during brief periods of social challenges. We manipulated T action in captive male Spotted antbirds to test whether this hormone is involved in the regulation of song and aggression. T-implants increased plasma androgen levels (T and dihydrotestosterone) and enhanced song in nonbreeding males. During a staged male-male encounter, T-implanted males sang more and were more aggressive than controls. In a second experiment, we blocked the two known T actions: its binding to androgen receptors and its conversion into estradiol by the enzyme aromatase. For this, we administered the androgen receptor antagonist flutamide (Flut) in combination with the aromatase inhibitor 1-4-6 androstatrien-3, 17-dione (ATD) to birds in breeding condition. ATD + Flut treatment significantly elevated plasma levels of luteinizing hormone, presumably via the lack of T feedback from its receptors. ATD + Flut-treated birds gave fewer spontaneous songs than control-implanted males. During staged male-male encounters, ATD + Flut-treated males did not sing at all and showed reduced aggressive behavior. Our data indicate that T can regulate aggressive behavior in these tropical birds. Although plasma T levels can be low year-round, Spotted antbirds may use T either by secreting it briefly during social challenges, by having a high sensitivity to T action, or by enzymatically converting circulating T precursors directly at the site of action. We hypothesize that plasma T levels are kept low in these year-round territorial birds to avoid potentially detrimental effects of tonically elevated T. Future treatment of nonbreeding birds with ATD + Flut will reveal whether T is indeed involved year-round in regulating aggressive behavior.</dcterms:abstract> </rdf:Description> </rdf:RDF>

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