[Pharmwaste] Female Starlings Duped into Mating with Duds

[DeBiasi,Deborah]

http://discovermagazine.com/2008/jul/10-female-starlings-duped-into-mati
ng-with-duds

Female Starlings Duped into Mating with Duds

07.10.2008
 
Environmental pollutants lead lesser males to sing louder and attract
more mates.

by Robert Kunzig 

It is hard to avoid the female sex hormone estrogen and all the
chemicals that mimic it: Not only do they show up in cosmetics and
cleaning products, but they are also commonly used to make plastic
bottles and line food cans. Some experts have traced estrogen-like
chemicals to increased rates of human breast cancer, and there is even
more evidence that they endanger animals by feminizing the sex organs of
male frogs and fish living downstream from sewage treatment plants. Then
there is one species of bird-the starling-in which environmental
estrogens have an especially surprising effect: Exposed male starlings
turn into better singers, duping female starlings into choosing mates
that may be bad bets.

The discovery comes from Cardiff University in Wales, where researchers
compared starlings raised in aviaries and fed a controlled diet with
those living at sewage treatment plants and feasting on earthworms
inhabiting the rocky filter beds. Since the worms survive on microbes
that degrade the sewage, the treatment-plant starlings consumed natural
human estrogen along with three estrogen mimics: DEHP, used to
manufacture polyvinyl chloride; DBP, found in nail polish; and bisphenol
A, common in hard plastic bottles.

At first, both groups of starlings appeared to behave normally,
exhibiting a natural seasonal cycle in which "the whole [brain]
mechanism for song shuts down in autumn, presumably to make room for
other centers that are more important-like finding food," says Katherine
Buchanan, a study leader. When the spring mating season rolled around,
estrogen in the male brain surged in both groups, triggering an
expansion of the vocal center and a burst of song. But for birds
consuming the estrogen cocktail, the vocal center grew even larger-and
they sang five times as long as uncontaminated birds and composed more
complex songs. In the lab, female starlings showed a preference for
those songs, perching near a loudspeaker that was playing them.

Blood tests, however, showed that the doped male starlings had
compromised immune systems, suggesting that they were less fit. The
starling population in Britain has dropped by half in the last four
decades, Buchanan says, mostly because humans have been encroaching on
their habitat-but perhaps also because pollutants are creating a siren
song that has bewitched the females, luring them to reproduce with more
musical, but less healthy, mates.


Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032