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Nazca Booby - Sula granti
Nazca Booby - Sula granti

[Image: Nazca-booby-in-flight.jpg]

Scientific classification
Kingdom:  Animalia
Phylum:  Chordata
Class:  Aves
Order:  Suliformes
Family:  Sulidae
Genus:  Sula
Species:  Sula granti  Rothschild, 1902

The Nazca booby (Sula granti) is a colonial seabird in the family Sulidae, native to the eastern Pacific.

The species has a yellow iris, orange and pinkish beak, black facial skin in the form of a mask, and grey feet. Adults present white plumage with black tips of the wings and tail. The female is bigger and heavier than the male, has a slightly differently colored beak, and squawks while the male whistles. Chicks are snow white and fluffy, plumage changing to grey along with beak and feet upon fledging.

[Image: Nazca-booby-hunting.jpg]

The genus Sula was previously placed in the order Pelecaniformes, but recently was collected in the family Sulidae and order Suliformes, together with 8 other genera. The Nazca booby was considered conspecific with the masked booby but was reassigned to a separate species based on mitochondrial DNA analyses. It is likely to have diverged 400,000-500,000 years ago.

The species occurs in the eastern Pacific from the islands in Baja California to the Galápagos Islands and the Isla de la Plata in Ecuador and Malpelo in Colombia.


The Nazca booby preys on small fish caught by diving at high speed from flight into the ocean. The main food species is South American pilchard, but also take flying fish, anchovies and squid, specially during the El Niño events, when sardine numbers are low. Because of their sexual dimorphism, females tend to feed on bigger prey and dive deeper.

[Image: Nazca-boobies-sleeping.jpg]

The Nazca booby nests near cliffs on bare ground with little to no vegetation. The male chooses and defends a territory, then enters into courtship to attract females.
Like many seabirds, the species has a long lifespan combined with low annual reproduction and long periods of development in the young. Clutch size is one or two eggs, due to the low hatching success, however when 2 eggs are laid and they both hatch, it is common for only one of the chicks to survive.
While many species of birds regulate egg temperature via an incubation patch, a layer of bare skin that allows birds to transmit heat into their eggs, the Suliformes instead use the skin on their webbed feet in addition to heat transferred from the breast. The feet are heavily vascularized, especially during the nesting period. Both the male and the female show parental care. Usually the chick that hatches first is bigger and becomes aggressive towards its sibling, excluding it from feeding and eventually starving it.
The energy investment on the parent’s part is very high, so their metabolic rates change during the nesting season. This causes both parents to lose similar amounts of body weight and suffer a decline in their immune system activity. This adjustment does not take place when the parents decide not to nest, a decision that is mostly driven by food availability, which in turn depends on ocean current and climate patterns such as those driven by the El Niño oscillation.

[Image: Male-and-female-Nazca-boobies-allopreening.jpg]


The Nazca booby is classified as Least Concern by the IUCN. Although populations are thought to decrease to some extent, this decline is not strong enough to require classification in a threat category. Some of the factors that influence the decrease of populations are overfishing and marine pollution.

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

February 12, 2019 by Alicia Roberts, Wake Forest University

[Image: momsrewardfe.jpg]
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 species, 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 females, 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."

Journal Reference:
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


  1. Under life‐history theories of ageing, increased senescence should follow relatively high reproductive effort. This expectation has rarely been tested against senescence varying between and within the two sexes, although such an approach may clarify the origins of sex‐specific ageing in the context of a given mating system.
  2. Nazca boobies (Sula granti; a seabird) practise serial monogamy and biparental care. A male‐biased population sex ratio results in earlier and more frequent breeding by females. Based on sex‐specific reproductive schedules, females were expected to show faster age‐related decline for survival and reproduction. Within each sex, high reproductive effort in early life was expected to reduce late‐life performance and accelerate senescence.
  3. Longitudinal data were used to (a) evaluate the sex specificity of reproductive and actuarial senescence and then (b) test for early‐/late‐life fitness trade‐offs within each sex. Within‐sex analyses inform an interpretation of sex differences in senescence based on costs of reproduction. Analyses incorporated individual heterogeneity in breeding performance and cohort‐level differences in early‐adult environments.
  4. Females showed marginally more intense actuarial senescence and stronger age‐related declines for fledging success. The opposite pattern (earlier and faster male senescence) was found for breeding probability. Individual reproductive effort in early life positively predicted late‐life reproductive performance in both sexes and thus did not support a causal link between early‐reproduction/late‐life fitness trade‐offs and sex differences in ageing. A high‐quality diet in early adulthood reduced late‐life survival (females) and accelerated senescence for fledging success (males).
  5. This study documents clear variation in ageing patterns—by sex, early‐adult environment and early‐adult reproductive effort—with implications for the role mating systems and early‐life environments play in determining ageing patterns. Absent evidence for a disposable soma mechanism, patterns of sex differences in senescence may result from age‐ and condition‐dependent mate choice interacting with this population's male‐biased sex ratio and mate rotation.
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