Murielle Ålund, Uppsala University (IMAGE) Uppsala University Caption In a study published in Behavioral Ecology researchers from Uppsala University show that the same type of sperm is not always the best for all male birds. Depending on how attractive or dominant you are you might be more successful with longer or shorter sperm. Credit Dr. Janette Boughman (Michigan State University). Usage Restrictions May only be published in connection to reports about the research by Åhlund et al. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.