Seagulls: Are males the weaker sex?

May 07, 2008

Male seagulls may be more vulnerable to their environment during embryonic development than females, according to Maria Bogdanova and Ruedi Nager from the University of Glasgow in the UK. Until now, the sex differences in developmental rate and susceptibility to unfavorable conditions during the embryonic stage in birds have received little attention. The paper has just been published in Springer’s journal, Behavioral Ecology and Sociobiology.

In many birds, siblings hatch at different times, resulting in age hierarchies within broods, with younger chicks often suffering reduced competitive ability and poorer survival compared to older siblings. During the last phase of incubation, birds’ auditory system is developed and embryos communicate with each other by auditory stimuli. These vocalizations may act as a cue for later-developing embryos about forthcoming competition, and there is evidence that they can respond to these cues by accelerating their hatching time, to reduce their age disadvantage. However, it is unclear whether this flexibility in developmental rates is sex-specific.

Bogdanova and Nager experimentally manipulated the social environment of herring gull embryos and tested whether sibling contact during the embryonic stage affects the developmental rate of males and females differently, and whether this has consequences for their post-hatching performance. The last-laid eggs – female gulls commonly lay three eggs - were incubated either alone with no information about the presence of older siblings (experimental group), or in contact with other eggs which provided information about the presence of more advanced embryos (control group, replicating natural conditions). Post-hatching, the chicks were reared either with nest mates or alone.

The researchers found a sex-specific effect of social environment on hatching duration and fledging* condition. When incubated in isolation, males hatched faster than females but both sexes fledged in similar, relatively good, condition. In contrast, when incubated with normal between-embryo contact, males were unable to hatch as fast and fledged in significantly poorer condition than females, regardless of whether they were reared singly or in a brood.

The authors conclude that their findings confirm that there are differences in the way male and female herring gull chicks respond to the challenges of hatching at different times. It would appear that females have the upper hand.

Source: Springer

Explore further: Chemical spill had 'no impact on health': Costa Rica

Related Stories

How an RNA gene silences a whole chromosome

Apr 27, 2015

Researchers at Caltech have discovered how an abundant class of RNA genes, called long non-coding RNAs (lncRNAs, pronounced link RNAs) can regulate key genes. By studying an important lncRNA, called Xist, ...

Evolution puts checks on virgin births

Apr 17, 2015

It seems unnatural that a species could survive without having sex. Yet over the ages, evolution has endowed females of certain species of amphibians, reptiles and fish with the ability to clone themselves, ...

Scientists unveil sex-linked control of genes

Apr 03, 2015

Many proteins interact with an RNA molecule called Xist to coat and silence one X chromosome in every female cell. Learning how genes are targeted and silenced may help researchers studying sex-specific diseases.

Detailing heterochromatin formation at the onset of life

Apr 01, 2015

Antoine Peters and his group at the Friedrich Miescher Institute for Biomedical Research (FMI) have elucidated the mechanisms controlling the packaging of chromatin in the early embryo. They have identified ...

Recommended for you

Hitting the borders of expansion

3 hours ago

Why does a species not adapt to an ever-wider range of conditions, gradually expanding its geographical range? In their paper published on May 5 in PNAS (Proceedings of the National Academy of Sciences), Jitka Polecho ...

Fire linked to dieback spread

4 hours ago

Fire has the potential to increase the range and severity of Phytophthora dieback in native plant communities infected with the disease, suggests a study at the Stirling Range National Park near Albany.

How mixing light with salt makes a smolt?

4 hours ago

For decades, researchers have tried to find out what regulates changes in salmon when they transform from being freshwater to saltwater fish. Now they have come a little closer to an answer.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.