 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
| . |  |
. |
High Hormone Levels In Seabird Chicks Prepare Them To Kill Their Siblings
Winston-Salem NC (SPX) Jul 01, 2008 The Nazca booby, a Gal�pagos Island seabird, emerges from its shell ready to kill its brother or sister. Wake Forest University biologists and their colleagues have linked the murderous behavior to high levels of testosterone and other male hormones found in the hatchlings. The elevated levels of male hormones, called androgens, increase aggression in both male and female chicks and prepare the birds to fight to the death as soon as they hatch, said David J. Anderson, professor of biology at Wake Forest and project leader. Much of the field work was completed by Martina Muller, while she was a graduate student at Wake Forest. "The older of two Nazca booby hatchlings unconditionally attacks and ejects the younger from the nest within days of hatching," Anderson said. Because Nazca boobies have difficulty raising more than one chick, it is important for the older chick to vanquish the younger one in order to increase its own chances of survival. According to the study, the high hormone levels also cause the surviving chicks to behave like bullies after they grow up. They frequently seek out nestlings in their colony, and during those visits they often bite and push around the defenseless youngsters. Blood samples were taken from Nazca booby chicks within 24 hours of hatching. In 15 nests with two eggs, blood samples were taken from both hatchlings. Samples were also taken from 15 hatchlings in one-egg nests. Then, blood hormones were analyzed by researchers at the University of Maryland, who co-authored the study. For comparison, the researchers did the same for blue-footed boobies, a closely related species. The researchers suspect that the Nazca booby hatchlings experience the high level of aggression-related hormone during a "sensitive period" in their growth, when long-term growth patterns are easily affected. Some Nazca booby nestlings experience a one-two hormonal punch, raising their aggression hormones even higher when they actually have a nest mate. The nestlings that fight siblings become bigger bullies as adults than the Nazca booby nestlings who never fight. "The hormones that are part of this epic battle early in life seem to permanently change some aspects of their social personality," Anderson said. Nazca booby chicks have aggression-related hormone levels three times as high as their less aggressive cousins, the blue-footed boobies. Blue-footed boobies do not have the same lethal fights right after hatching and do not go on to bully their fellow birds as adults. Community Email This Article Comment On This Article Share This Article With Planet Earth
Related Links Wake Forest University Darwin Today At TerraDaily.com
Early Bird Project Really Gets The Worm
Baton Rouge LO (SPX) Jul 01, 2008Scientists from the LSU Museum of Natural Science, or MNS, recently participated in a project joining together the most prominent ornithological research programs in the world. |
|
|
| The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement |
del.icio.us
Digg
Reddit
YahooMyWeb
Google
Facebook