Mom's reward: Female Galapagos seabird has a shorter lifespan than males

February 12, 2019 by Alicia Roberts, Wake Forest University
Nazca booby adult and nestling in the Galápagos Islands. Credit: J. Howard.

The male Nazca booby, a large seabird of the Galápagos Islands, often outlives the domineering female of the species, according to new research from Wake Forest University published today in the Journal of Animal Ecology. Why? It's a story of rotating sex partners, the cost of being a parent and how the body falls apart in old age.

In the annual quest for the best breeding mate, the older female Nazca booby's choice to pair with a younger mate may contribute to lifespan differences within the , said Emily Tompkins, the lead researcher who co-authored "Sex-specific patterns of senescence in Nazca boobies linked to mating system" with biology professor David J. Anderson.

The study is the latest in decades-long research by Anderson, who studies several seabird species. He and his students have been banding Nazca boobies born on Española Island, a roughly 37-square-mile Galápagos Island outpost, for more than 30 years.

The , which are about 16 percent larger than the males, control mating and decide when it's time to "divorce" a current partner for one with a better chance at successful breeding. An excess of adult males in the Nazca booby population has led to this practice of "serial monogamy." When the males enter their late teens, their chance of breeding plummets, while females continue to breed nearly every year. So, the older females of the species often choose a younger mate each breeding season. And that seems to have led to a shorter lifespan for females, Tompkins said.

"Reproducing can reduce adult survival in the following year, so the higher breeding participation by females across the lifespan, and especially in old age, probably contributes to shorter lives," she said.

Nazca boobies can live into their late 20s, making them an excellent species for studying decline in old age.

"If you're interested in aging patterns in human systems, we have few opportunities to collect comparative data from other species," Anderson said. "This banded, known-age, population followed since infancy can help us understand what factors lead some individuals to age well and others to age poorly."

Only the long-term nature of the Galápagos study has allowed the Nazca booby to fulfill that comparative role. The potentially long lifespan of Nazca boobies means that Anderson has waited decades to observe breeding behavior and reproductive success in old birds.

Several other factors might contribute to the female Nazca booby's short lifespan, the researchers found:

  • Females receive poorer quality of care as fledglings, because parents don't always account for how much more food the larger daughters need.
  • Females play a greater role in feeding the chick each breeding season, and that effort might take a toll over the greater number of breeding episodes.

But, Tompkins explained, we're just beginning to understand the differences in aging among Nazca boobies.

"Some of this variation is explained by sex, environment, and other properties of individuals," she said. "We're so fortunate to have decades of data on hand to address this topic."

Explore further: A Galapagos seabird's population expected to shrink with ocean warming

More information: Emily M. Tompkins et al, Sex-specific patterns of senescence in Nazca boobies linked to mating system, Journal of Animal Ecology (2019). DOI: 10.1111/1365-2656.12944

Related Stories

The survival of sea birds affected by ocean cycles

May 17, 2018

In a general context of climate change, researchers at the Centre d'écologie fonctionnelle et évolutive (CNRS/Université de Montpellier/Université Paul Valery/EPHE-PSL) and their international partners revealed the impact ...

Lack of breeding threatens blue-footed boobies' survival

April 21, 2014

Blue-footed Boobies are on the decline in the Galápagos. A new study appearing in the journal Avian Conservation and Ecology indicates numbers of the iconic birds, known for their bright blue feet and propensity to burst ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...

0 comments

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.