Wednesday, June 07, 2006

Testosterone Boosts Birds' Attractiveness, But Leads To Shorter Lifespan

Dating and mating are unique for many species, but for dark-eyed junco songbirds, researchers led by North Dakota State University assistant biology professor Wendy Reed, Ph.D., found something new.

Published in the May issue of The American Naturalist, the team’s study found that male birds with extra testosterone were more attractive to females and produced more—but smaller—offspring. Smaller offspring had lower survival rates than larger offspring. The extra testosterone also made the male birds sing more sweetly and fly farther.

The testosterone-laden birds proved irresistible to older, more experienced female juncos, but that attractiveness carried some risks. Elevated testosterone levels increased activity—possibly attracting more predators—made the male, dark-eyed juncos more susceptible to disease and shortened their lifespan. “They had lower immune function and paid a cost with lower survival rates,” said Reed.

The increased testosterone also made the dark-eyed male juncos less attentive parents to their offspring as they made fewer nest visits, resulting in less food delivered and less time spent at the nest. The research team monitored more than 400 junco nests in the Appalachian Mountains of Virginia for nine breeding seasons.

One group of dark-eyed juncos in the study received tubes implanted under the skin which contained testosterone and the control group of birds received implants that were left empty. Implants were removed from birds recaptured at the end of each breeding season.

Study results are featured by the American Association for the Advancement of Science, in a podcast called Testosterone Tradeoff at http://www.scienceupdate.com/index.cfm. The podcast notes that such feathered Casanovas have a better sex life, but a shorter one than birds not receiving the extra testosterone in the study. Reed led the research as part of her postdoctoral work.


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AGRI-INFO/JUNE 7, 2006



TITLE: TESTOSTERONE BOOSTS BIRDS’ ATTRACTIVENESS, BUT LEADS TO SHORTER LIFESPAN


ALAM BA NINYO NA NATUKLASAN NG MGA EKSPERTO NA ANG MGA LALAKING IBON NA MERONG EKSTRA HORMONE NA TESTOSTERONE AY MAS KAAKIT-AKIT SA MGA BABAENG IBON?

LUMABAS SA PANANALIKSIK NG MGA EKSPERTO NG NORTH DAKOTA STATE UNIVERSITY SA PANGUNGUNA NI ASSISTANT BIOLOGY PROFESSOR WENDY REED, PH. D., NA BAGAMAN MAS KAAKIT-AKIT ANG MGA LALAKING IBON NA ITO AT MAS MARAMI ANG KANILANG ANAK, NGUNIT MAS MAIGSI NAMAN ANG BUHAY.

ITO AY NAPATUNAYAN NG MGA EKSPERTO SA GINAWA NILANG PAG-AARAL SA HANAY NG DARK-EYED JUNCO SONGBIRDS NA NAKITAAN NG EKSTRANG KAKAYANAN, MAS MAGALING UMAWIT AT MAS MALAYO KUNG LUMIPAD.

NGUNIT KAAKIBAT NITO ANG PROBLEMA TULAD NGA NG SUSUNOD NA HENERASYON NG SONGBIRD NA ITO NA MAS MAAGANG MAMATAY BAGAMAN SILA AY MAS MARAMI SA KARANIWAN.

ANG DAGDAG NA TESTOSTERONE LEVEL AY NAKAPAGPAPATAAS DIN SA AKTIBIDADES NITO NA POSIBLENG SAMANTALAHIN NG MGA SAKIT AT MAS MADALING MAMATAY.

AYON KAY REED, MERON SILANG MABABANG IMMUNE SYSTEM NA ANG RESULTA AY MABABA RING SURVIVAL RATES.

ANG MATINDI PA NITO ANG DARK-EYED MALE JUNCOS NA MAY EKSTRA HORNOME AY HINDI MAGALING NA MGA MAGULANG DAHIL HINDI MASYADONG NAAALAGAAN ANG KANILANG MGA ANAK, NA MAAARING MAGRESULTA SA KAGUTUMAN AT TULUYANG KAMATAYAN.

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