Sula variegataPeruvian booby

Geographic Range

Peruvian boobies (Sula variegata) are located on the western coast of South America. They range from southwest Columbia to Isla Grande de Chiloé. There are also vagrant populations in Panama. Their breeding range expands eastward of their native range, from northern Peru to central Chile. They typically breed on cliffs, and typically select cliffs on small islands. Their non-breeding range extends along the western coast of South America, from southwest Columbia to the Isla Grande de Chiloé. (BirdLife International, 2016; Zavalaga, et al., 2009)


Peruvian boobies typically forage in relatively cool waters (13-22 degrees Celsius) near the Isla Macabi. They inhabit cliffs with elevations of 100-2500m and small islands where they nest, mate, and forage for fish. Boobies nest in isolated groups of 2-3 pairs on the ledge of perpendicular cliffs and in the tens of thousands on smooth sloping hillsides. They nest eastward from their fishing location. Nest shape determines how many chicks can be laid, density, and slope of the substrate the nest is located. Their nest consists of low rims of guano and pebbles. Competition for nesting space play a significant role in where they nest. (Boyd, et al., 2015; Duffy, 1983a; Duffy, 1987; Ludynia, et al., 2010; Weimerskirch, et al., 2010; Zavalaga, et al., 2010)

  • Range elevation
    100 to 2500 m
    328.08 to 8202.10 ft

Physical Description

Peruvian boobies have predominately brown feathers and wings with white feather markings on the tips (e.g., mottling). They have a distinct grey bill and legs with a bright-white head and under throat. Their eyes are a deep red-wine color. Females are typically 19% heavier than males and their wingspans are 3-4% larger than males. The average weight of Peruvian boobies is 1416.5 g (range 1290-1543 g). The average length of Peruvian boobies is 73.5cm (range 71-76cm). On average, both sexes have a wingspan of 150 cm, but females tend to be slightly longer. Nelson (1978) stated juvenile boobies are a dingy-greyish color, dark and somber in color below, with bordered white feathers on their breast and bellies covering a sub-terminal brownish patch. Their wings and back are duller in color than in adult boobies due to dorsal plumage. They have finely ash-streaked heads and neck and yellowish grey iris, before they turn brown and then red as they reach adulthood. Compared to adult boobies their face and bill are bluish and legs and feet are a lighter blue-grey. Nelson (1978) also stated that egg lengths are 53-61mm. There is no published information on egg weight. (Nelson, 1978; Schulenberg, 2010; Zavalaga, et al., 2009)

  • Sexual Dimorphism
  • female larger
  • Range mass
    1290 to 1543 g
    45.46 to 54.38 oz
  • Range length
    71 to 76 cm
    27.95 to 29.92 in
  • Average wingspan
    150 cm
    59.06 in


Peruvian boobies are monogamous. Once female boobies choose their mate, the pair are lifelong mates. Their specific mating ritual is understudied, but a member of the genus, blue-footed boobies (Sula nebouxii), have a complex mating ritual. Kiere and Drummond (2014), stated female blue-footed boobies pick their mates according to social status or relative male age, body size, condition, foot color and breeding success. Kiere and Drummond (2014), also reported female blue-footed boobies are likely to extrapair (more than one mate) if paired with low-quality males and female boobies with high-quality males are choosier if they choose to have an extra mate. According to Taylor et al. (2012), there are hybrid zones between blue-footed boobies and Peruvian boobies, but they occur at low frequencies. The hybrids were usually produced between female Peruvian boobies and male blue-footed boobies. It is hypothesized this is due to potentially due to strong (premating) reproductive isolation in the two species. (Kiere and Drummond, 2014; Taylor, et al., 2010; Taylor, et al., 2012)

Peruvian boobies can breed up to twice a year depending on food availability, when the fitness benefits are at their optimal conditions for both parents and their offspring (Passuni et al, 2016). Passuni et al, (2016) states that they are year-round breeders, in late spring and early summer (November-December) is when their incubation rates are highest, because the abundance of anchovy are high. The breeding period from egg laying to chick fledging is 6.7 months (Passuni at al., 2016). Female boobies can lay up to 4 eggs per season, but usually lay 2-3. Eggs are pale blue in color. Booby chicks hatch within 4-5 weeks of incubation. According to Ricklefs (2002), when chicks hatch they are altricial and completely dependent on their parents. Chicks begin fledging within 78-105 days of hatching. (Duffy, 1983a; Passuni, et al., 2016; Ricklefs, 2002; ; Taylor, et al., 2010; Zavalaga, et al., 2009)

  • Breeding interval
    Peruvian boobies are year-round breeders but tend to breed 1-2 times a year.
  • Breeding season
  • Range eggs per season
    1 to 4
  • Average eggs per season
  • Range time to hatching
    4 to 5 weeks
  • Average time to hatching
    4-5 weeks
  • Range fledging age
    78 to 105 days

Peruvian boobies are monogamous; once they mate, they are lifelong partners. When chicks hatch they are altricial and completely depend on their parents. Male and female boobies help protect and provide for the chicks. They both build the nest to provide for their offspring. Building a nest is very important for the survival of chicks. Nest shape, the materials they are made of, the substrate they are built on, and the density can all determine how many chicks can be reared in the nest. According to Duffy (1983), the densities of nests are very high, they usually build (2-3) nest per square meter. Nelson (1978), stated breeding is a slow process and it can take booby pairs more than a month to build their nest. Their nest sites are on exposed rocky cliff faces that are generally inaccessible to human predators. This is beneficial because it facilitates easier take-offs and landing when boobies return from foraging. Male and female boobies both incubate the eggs after hatching and forage for their offspring. Male boobies are smaller in size which allows them to forage at further distances. Female boobies are heavier than males, allowing them to dive deeper. This is beneficial for their offspring expanding their foraging limits in times when there is scarce food supply. It is understudied if the foraging patterns of booby parents change once the chicks are hatched, but preferentially hunt anchoveta, especially if they are foraging for chicks. On average, 30% of juvenile boobies’ diets consist of anchovies. Booby chicks are typically feed by their parents until they are 78-105 days old; at this time chicks fledge. (Duffy, 1983b; Nelson, 1978; Passuni, et al., 2016)

  • Parental Investment
  • altricial
  • male parental care
  • female parental care
  • pre-fertilization
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female


Peruvian boobies' maximum lifespan has not been reported but according to Weimerskirch (2001), members of the Sulidae family have average adult life expectancies of 17.2-20.5 years in the wild. It is likely Peruvian boobies have a similar lifespan in the wild. Peruvian boobies are not kept in captivity. (; Weimerskirch, 2001)


Brown pelicans (Pelecanus occidentalis), and guanay cormorants (Leucocarbo bougainvillii) compete with boobies for nesting space. Duffy (1983) stated brown pelicans outcompeted the other two species for nesting space. When boobies and cormorants are defending their territories, it ends in a standoff 95% of the time, but when they are not defending their territory it ends in a standoff 66% of the time. Out of 33% of standoffs between boobies and cormorants, boobies won 21% of the time. Duffy (1983) found these birds defend their territory with jabs preceded by "yes head-shaking" by boobies and extended-neck threats by cormorants. Duffy (1983) stated these behaviors also lead to "sky pointing" preceding or following jabbing. Compared to blue-footed boobies (Sula nebouxii), and brown boobies (Sula leucogaster), the Peruvian boobies have shorter foraging trips. Boobies forage during the daylight hours, 1-3 times a day for short bouts of 1-5hrs. Zavalaga et al. (2009) studies a boby populatrion and reported that individuals, on average, spent 92% of their waking time flying, 6% sitting on water, and 2% diving. There are two ways that boobies dive: V- and U-shaped dives. V-shaped dives are used when trying to reach maximum depths, then returning immediately to the surface. U-shaped dives are used when they spend a few seconds at maximum depth before returning to the surface. Their foraging range varies between 4.5-68 km, the total distance traveled in foraging range from 14-179 km, and their foraging areas (where they dive) are located 1-67 km from colonies. Based upon Zavalaga et al. (2010), boobies forage by straight or, less commonly, looped routes. Boobies’ feeding activities are usually at the furthest end point of the route, and they return home parallel to the starting route. Looping routes are wider and they feed at more than one location throughout trip. (Duffy, 1983a; Zavalaga, et al., 2009; Zavalaga, et al., 2010)

  • Average territory size
    0.7 m^2

Home Range

The foraging range and home range are the same pertaining to Peruvian boobies. Zavalaga et al. (2010), stated boobies average foraging range is 25 km but can vary between 4.5-68 km. The average distance traveled in their foraging range is 69 km but can vary between 14-179 km. Their foraging areas are located (1-67 km) from colonies, but on average are 21 km. Their foraging areas were identified by their diving events. Duffy (1983) reported their home range is much larger than their territory size which is their nest size, ca. 0.7 square meters. (Zavalaga, et al., 2009; Zavalaga, et al., 2010)

Communication and Perception

Peruvian boobies use vocal calls to communicate within colonies. Nelson (1978) reported that, sounds have been classified with names such as bicker and chitter, loud-calling, whistles, grunts, and trumpet-like. They use these sounds to communicate when they are hunting and in daily communication. Males typically use higher-pitched whistles to communicate while females use trumpet-like honks or quacks to communicate. Female boobies seem nosier than males, producing most sounds in the colony. Nelson (1978) found that, females rising and falling in pitch and amplitude continuing for 30-40 seconds separate articulations usually go on for 6-12 seconds. When female boobies fight they will use a continuous moaning call. It takes juveniles a few years to be able to produce such unique vocalizations. Duffy (1983) stated brown pelicans (Pelecanus occidentalis) outcompeted the other two species for nesting space. Cormorants (Leucocarbo bougainvillii) and boobies jab at pelicans but the pelican typically ignores them. Duffy (1983) found these birds defend their territory with jabs preceded by "yes head-shaking" by boobies and extended-neck threats by cormorants. Duffy (1983) stated these behaviors also lead to "sky pointing" preceding or following jabbing. There is no known information on how boobies use chemical signals. (Duffy, 1983b; Duffy, 1983a; Nelson, 1978; Passuni, et al., 2016)

Food Habits

Peruvian boobies are carnivorous birds whose adult diets consist of primarily anchoveta, and sometimes sardines (family Clupeidae) and mackerel (family Scombridae). They typically forage in the morning through the early evening. They are opportunistic if their food supply is scarce, but preferentially hunt anchoveta, especially if they are foraging for chicks. They are plunge diving hunters, and they fly about 14.9 m/s. On average, they dive between 2.8 m and 5.8 m for 1.9 s to 4.3 s, and they have been recorded diving up to 10.4 m. Ludynia et al. (2009) showed that a population of foraging boobies in Isla Pajaros, Chile spent 90.2% of their time flying, 8.8% diving, and 1.0% swimming. The same study also found that these boobies forage 10-50 km offshore in the northern and southeastern direction from their nesting site. In non-El-Nino years these birds foraged 4-5 km from the shoreline. Chick diets consist of a greater variety of species than adults and include Inca scads (Trachurus murphyi), king gars (Scomberesox saurus), Araucanian herrings (Strangomera bentincki), silversides (Odonthesthes regis), cabinza grunts (Isacia), squids (class Cephalopoda), and anchovies (Engraulis ringens). Adult boobies regurgitate food from their forage to feed juveniles. On average, 30% of juvenile boobies’ diets consist of anchovies. (Jahncke and Goya, 2000; Ludynia, et al., 2010; Zavalaga, et al., 2010)

  • Animal Foods
  • fish
  • mollusks


Owls and large birds of prey may prey upon booby chicks. The main predators of adult boobies are humans (Homo sapiens). Sharks are also occasional predators to foraging boobies, but particular shark species have not been reported. (Passuni, et al., 2016; Duffy, 1983b; Passuni, et al., 2016; Zavalaga, et al., 2009)

  • Known Predators

Ecosystem Roles

Duffy (1983) stated ticks and other ectoparasites strongly affect Peruvian booby nesting success, nest structure, and the duration the nest is used. Ticks feed on adult Peruvian boobies and booby chicks, which causes them to slowly desert their nests. Tick species were denser in deserted booby nests than in active booby nests. This causes a decline in booby population because a decrease in active nesting areas causes a decrease in successful fledging of young. Tick species include Ornitodoros yunkeri, Carios amblus, and Ixodes brunneus. Wing lice species include Pentinopygus annulatus. Duffy (1983) stated that frequent human harvesting of guano is more effective at controlling ticks than tick predators. (Clay, 1963; Clifford, et al., 1980; Duffy and Duffy, 1986; Duffy, 1983b; Hoogstraal, et al., 1985)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Peruvian boobies are the second most important guano-producing seabird. This benefits organic farmers because guano can be used to help fertilize crops due to its high concentration of nitrogen. (; Weimerskirch, 2001)

  • Positive Impacts
  • produces fertilizer

Economic Importance for Humans: Negative

There are no known adverse effects of Peruvian boobies on humans.

Conservation Status

Peruvian boobies are listed as a species of "Least Concern" on the IUCN Red List. They hold no special status on US Migratory Bird Act, Us Federal List, CITES, and State of Michigan List. Threats to Peruvian boobies include over fishing of their common prey species, Peruvian anchoveta (Engraulis ringens) their main food source. Additional threats include El Nino events. In these years, ocean temperatures rise 3-5 degrees C above average. Ocean surface height can rise 15-33cm above normal, also affecting salinity and currents. This affects foraging, alters the food web, and causes the population numbers of boobies to decline. There are no conservation efforts in place. (Halls, et al., 2010; Taylor, et al., 2010)


Kioshi Lettsome (author), Radford University, Alex Atwood (editor), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Karen Powers (editor), Radford University, Joshua Turner (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.



living in the southern part of the New World. In other words, Central and South America.

World Map


uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males


eats mollusks, members of Phylum Mollusca


Having one mate at a time.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


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