Animal Diversity Web

Ge­o­graphic Range

Brown boo­bies, Sula leuco­gaster, are com­mon res­i­dents of Puerto Rico and the Vir­gin Is­lands. The dis­tri­b­u­tion is de­scribed as pantrop­i­cal, be­tween lat­i­tudes 30 de­grees North and 30 de­grees South, though it ex­tends to about 34 de­grees South in the cen­tral Pa­cific. Brown boo­bies occur in the Caribbean Sea, Red Sea, and the At­lantic, Pa­cific, and In­dian Oceans. They also in­habit seas north of Aus­tralia. The sub­species Sula leuco­gaster brewslei and Sula leuco­gaster ete­si­aca live along the Pa­cific coast of Mex­ico and the Pa­cific coast of Cen­tral and South Amer­ica, re­spec­tively.

Al­though brown boo­bies may have his­tor­i­cally in­hab­ited the Florida Keys, clear ev­i­dence is lack­ing. Trop­i­cal storms oc­ca­sion­ally blow in­di­vid­u­als of this species well out­side of their typ­i­cal ge­o­graphic bound­aries - such an ex­am­ple is the Oc­to­ber 2008 ob­ser­va­tion of a lone Sula leuco­gaster at Clay­tor Lake (Pu­laski County) in south­west­ern (in­te­rior) Vir­ginia. (Mack and Larner, 2009; Raf­faele, 1989; Schreiber and Nor­ton, 2002)

• Biogeographic Regions
• neotropical
  • native
• australian
  • native
• oceanic islands
  • native
• indian ocean
  • native
• atlantic ocean
  • native
• pacific ocean
  • native

Habi­tat

Brown boo­bies use coral atolls and vol­canic stack is­lands for nest­ing in trop­i­cal or sub­trop­i­cal wa­ters. When faced with lit­tle or no com­pe­ti­tion for space, they pre­fer wide open spaces at sea level. They have, how­ever, been found on cliffs and hill­sides. (Chaves-Cam­pos, and Tor­res, 2002; Schreiber and Nor­ton, 2002)

• Habitat Regions
• tropical
• saltwater or marine

• Aquatic Biomes
• coastal

• Range elevation

  0 to 15 m

  0.00 to 49.21 ft

Phys­i­cal De­scrip­tion

Adult feather col­oration is sim­i­lar be­tween sexes. There are small dif­fer­ences among males of the sub­species S. leuco­gaster brewslei and S. leuco­gaster ete­si­aca. Gen­er­ally brown boo­bies have dark brown heads, necks, and backs with bright white un­der­bel­lies. A sharp line sep­a­rates the lower breast where the brown fades to white. The under wings are mostly white ex­cept for a vari­able dark bar that is rel­a­tively nar­row and ex­tends from armpit to carpal joints. The sub­species men­tioned ear­lier tend to have a light gray to white head that grad­u­ally turns brown at the neck. Over­all their necks and upper backs are darker than other Sula leuco­gaster sub­species. Ju­ve­niles have no doc­u­mented dif­fer­ences be­tween sexes or sub­species. But are gen­er­ally a brown­ish color on their head, neck, and back with a no­tice­able band across the lower breast which leads to the mot­tled brown and whitish un­der­parts (un­der­parts grad­u­ally at­tain full white color over first 2 years). The under wing-coverts (feath­ers that cover the bases of the quill feath­ers) are gen­er­ally gray, which con­trast sig­nif­i­cantly with the rest of the under wing. Adult soft part col­ors vary slightly be­tween males and fe­males, with no doc­u­mented vari­a­tion among sub­species. Males have gray-blue to steely-blue skin around the eyes and yel­low to bright yel­low skin at base of mandible. Fe­males are much the same, ex­cept for face skin that is al­ways bright yel­low. In both gen­ders the bills and feet range in color from bright yel­low, bluish yel­low, green­ish yel­low, light-pink, and gray.

Over­all dis­tin­guish­ing booby species isn’t dif­fi­cult, but ju­ve­nile red-footed boo­bies (Sula sula) look re­mark­ably sim­i­lar to ju­ve­nile brown boo­bies. Over­all length ranges from 64 to 85 cm, with fe­males on av­er­age being a few cm longer. Their wingspan is in the range of 132 to 155 cm. There is a slight dif­fer­ence in weight be­tween sexes, with fe­males usu­ally weigh­ing about 300 g heav­ier. The ranges for males are 950 to 1700 g and for fe­males is 1000 to 1800 g. (Schreiber and Nor­ton, 2002)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently

• Range mass

  950 to 1800 g

  33.48 to 63.44 oz

• Average mass

  1300 g

  45.81 oz

• Range length

  64 to 85 cm

  25.20 to 33.46 in

• Range wingspan

  132 to 155 cm

  51.97 to 61.02 in

Re­pro­duc­tion

Brown boo­bies are monog­a­mous. Males are the only gen­der ob­served per­form­ing mat­ing be­hav­iors, in­clud­ing sky-point­ing and parad­ing. In sky-point­ing, when a fe­male first ap­proaches, the male will stand up and throw his head into the air with neck stretched out as far as it can go. This is usu­ally ac­com­pa­nied by a unique whis­tle. This rit­ual is slightly dif­fer­ent from the other booby species, as it doesn’t in­volve a use of the wings. Parad­ing is just an ex­ag­ger­ated form of walk­ing, in which body pos­ture is un­usu­ally erect with an ex­ag­ger­ated sway. Other be­hav­iors that are thought to re­in­force pair bond­ing are mu­tual preen­ing, bill touch­ing, and bow­ing. Mu­tual preen­ing is where each pair bond will clean the other’s feath­ers. Bill touch­ing is done when­ever mates re­turn to their own ter­ri­tory after bow­ing. It has been noted that the mate reen­ter­ing the ter­ri­tory will make their ar­rival call and then per­form a slight bow (sim­i­lar to the bow de­scribed in ag­gres­sive be­hav­ior) un­less the bird reen­ter­ing is fly­ing in and its part­ner is on a nest, in which case that bird will per­form a seated bow. This is thought to be a form of greet­ing. (Schreiber and Nor­ton, 2002)

• Mating System
• monogamous

Brown booby breed­ing sea­son is de­pen­dent upon food avail­abil­ity. Events such as El Nino can dras­ti­cally shift nor­mal breed­ing sea­son for a few years. In the Caribbean and east Pa­cific, peak breed­ing months are De­cem­ber to Feb­ru­ary. In the cen­tral Pa­cific, the breed­ing sea­son lasts from De­cem­ber to March, but it's not un­com­mon to find them breed­ing year round. In Hawaii brown boo­bies breed from March to May. After eggs are laid, par­ents take turns in­cu­bat­ing for 42 days. Usu­ally brown boo­bies lay 2 eggs but only raise one chick past the fledg­ling stage. It is thought that hav­ing a sec­ond egg is for in­sur­ance pur­poses, in case one egg doesn't make it. The first chick hatches about 2 to 4 days be­fore the sec­ond. This chick will then push the other young from the nest with no in­ter­fer­ence from ei­ther par­ent. The ex­pelled chick will usu­ally die from heat ex­po­sure, lack of food, or pre­da­tion. The sur­viv­ing chick will con­tinue to be cared for in the pre-fledg­ling stage for close to 100 days, dur­ing which time both par­ents con­tinue to feed and pro­tect it. In the post-fledg­ling stage, it is not un­com­mon for young birds to go out on their own to learn how to hunt and so­cial­ize and then re­turn to their par­ents nest to be fed. This sort of be­hav­ior has been ob­served up to a year after reach­ing post-fledg­ling stage, but it typ­i­cally lasts 50 days. This vari­abil­ity is thought to be the re­sult of food avail­abil­ity. (Mellink, 2000; Schreiber and Nor­ton, 2002; Ter­shey, et al., 2003)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• oviparous

• Breeding interval

  Brown boobies breed once yearly.

• Breeding season

  Brown booby breeding times vary across the world, with most breeding occuring from December to March, although breeding may be year-round in some areas.

• Range eggs per season

  1 to 3

• Range time to hatching

  40 to 47 days

• Average time to hatching

  42 days

• Range fledging age

  96 to 120 days

• Average fledging age

  100 days

• Range time to independence

  42 to 365 days

• Average time to independence

  50 days

• Range age at sexual or reproductive maturity (female)

  240 (low) days

• Average age at sexual or reproductive maturity (female)

  1278 days

• Range age at sexual or reproductive maturity (male)

  240 (low) days

• Average age at sexual or reproductive maturity (male)

  1278 days

Both male and fe­male brown boo­bies in­cu­bate the eggs. Time on the nest is split evenly, with vary­ing amount of hours per sit­ting. Once eggs hatch, both par­ents par­tic­i­pate in feed­ing the young. There are no records about which gen­der feeds more often. When chick gets older and big­ger the par­ents might roost away from nest but will often re­turn to de­fend their nest ter­ri­tory and chick. This pre-fledg­ling care can con­tinue up to 100 days. Post-fledg­ling care can vary from 42 days up to 259 days with rare oc­cur­rences of ju­ve­niles re­turn­ing to par­ents nest up to a year after to beg for food. This fac­tor is thought to be con­trolled by local fish­ing con­di­tions. If food is plen­ti­ful and easy for ju­ve­niles to catch and learn how to hunt ef­fi­ciently, then it will be shorter. There have been no doc­u­mented cases of adult brown boo­bies show­ing post-fledg­ling chicks how to dive or hunt. How­ever, in an ex­per­i­ment by Yoda et al. (2007), hand-raised chicks were often much slower to reach peak div­ing lev­els than chicks raised by par­ents. (Schreiber and Nor­ton, 2002; Yoda, et al., 2007)

• Parental Investment
• altricial
• male parental care
• female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• extended period of juvenile learning

Lifes­pan/Longevity

Adult mor­tal­ity per year has been re­ported to be be­tween 3.3 and 7.7%. The max­i­mum known lifes­pan in the wild is 27.2 years. There have been no stud­ies to doc­u­ment av­er­age lifes­pans in the wild or cap­tiv­ity. ("AnAge Entry for Sula leuco­gaster", 2009)

• Range lifespan
  Status: wild

  27.2 (high) years

Be­hav­ior

There hasn't been enough stud­ies out­side of the breed­ing sea­son to de­ter­mine whether brown boo­bies mi­grate. They do dis­perse from nest­ing areas at the end of the breed­ing sea­son and re­turn 1 to 3 weeks be­fore lay­ing oc­curs, but they may sim­ply dis­perse to local wa­ters for for­ag­ing. Brown boo­bies moves around while on land with a wad­dling gait (sim­i­lar to a duck) and only hop when an in­truder comes into its ter­ri­tory. They have never been recorded climb­ing. Brown booby flight in groups is not pat­terned. They fly alone and in flocks to for­ag­ing areas. Brown boo­bies are es­ti­mated to fly at speeds up to 40 km/h and can glide ef­fi­ciently. Be­cause of their smaller size, males tend to be more agile than fe­males and both species are ca­pa­ble of land­ing on tree limbs, buoys, and ves­sels at sea. When on land dur­ing day, brown boo­bies spends a good deal of time preen­ing and reap­ply­ing water proof­ing oil se­creted from the uropy­geal gland. Brown boo­bies are ca­pa­ble of sleep­ing while stand­ing or sit­ting. Gen­er­ally, the bill is tucked over the back and into scapu­lars or with the neck drawn in and beak fac­ing for­ward. (Schreiber and Nor­ton, 2002)

• Key Behaviors
• terricolous
• flies
• glides
• diurnal
• motile
• sedentary
• territorial
• social
• colonial

• Range territory size

  1 to 5 m^2

Home Range

Brown boo­bies typ­i­cally de­fend an area of about 1 to 5 me­ters around nests. Size varies based on nest sub­strate and the den­sity of other brown boo­bies in the colony. No stud­ies have been done on de­fend­ing feed­ing areas. (Schreiber and Nor­ton, 2002)

Com­mu­ni­ca­tion and Per­cep­tion

There has only been one study on the var­i­ous calls of brown boo­bies. The re­sults of that study sug­gest vo­cal­iza­tions are used for sev­eral dif­fer­ent func­tions, in­clud­ing greet­ing mates, ag­gres­sion, and chicks beg­ging for food. Colonies as a whole are gen­er­ally not noisy, as more com­mu­ni­ca­tion is done through be­hav­ior. Males and fe­males use vo­cal­iza­tions in dif­fer­ent ways. Males emit a se­ries of soft whis­tles while fe­males are re­spon­si­ble for harsh quack­ing or honk­ing. These sounds be­come more pro­nounced when­ever they are faced with pos­si­ble in­tru­sion from an­other bird. Males calls be­come harsher and are held for longer while fe­males emit a sound known as a “roar-call”. This is an em­phatic shout that is in­tended to warn the in­truder to stay away from the nest. When these birds greet their mates as they re­turn from hunt­ing, they use their typ­i­cal sounds. How­ever, these calls are made softly while still far out and tend to get louder as they ap­proach the nest.

Hatch­lings have their own range of sounds, start­ing with peep­ing while still in the egg. While very young there seems to be no dis­cernible pat­tern to the food call, it is just a range of the noises they are able to make. As they get older it takes on a loud, raspy, repet­i­tive craa-craaaa.

Most com­mu­ni­ca­tion is ac­com­plished through be­hav­iors rather than sounds. An ex­am­ple of ag­gres­sive be­hav­ior will be seen mostly when claim­ing or main­tain­ing breed sites. Ag­gres­sive be­hav­iors are di­rected to­wards other birds as well as inan­i­mate ob­jects (shrubs or rocks). When per­form­ing ag­gres­sive be­hav­iors against other birds, brown boo­bies hop to­wards the in­truder with their neck and head stretched for­ward. When they get closer they bow and usu­ally emit a honk. If the in­truder does not back down the de­fend­ing booby will per­form a more ex­ag­ger­ated bow. If the in­truder still doesn’t back down, then the ter­ri­tory owner may rat­tle its bill to­wards the in­truder. This can es­ca­late to bill jab­bing with a down­ward slap of the wings. Some­times the de­fender will grab onto oth­ers bill or neck.

Only males have been ob­served per­form­ing mat­ing be­hav­iors, which in­clude sky-point­ing and parad­ing. Sky-point­ing is done when a fe­male first ap­proaches. The male will stand up and throw his head into the air with neck stretched out as far as it can go. This is usu­ally ac­com­pa­nied by a unique whis­tle. This rit­ual is slightly dif­fer­ent from the other booby species as it doesn’t in­volve a use of the wings. Parad­ing is re­ally just an ex­ag­ger­ated form of walk­ing. The body pos­ture is un­usu­ally erect with an ex­ag­ger­ated sway. Other be­hav­iors that are thought to re­in­force pair bond­ing are mu­tual preen­ing, bill touch­ing, and bow­ing. Mu­tual preen­ing is where each pair bond will clean the other’s feath­ers. Bill touch­ing is done when­ever mates re­turn to their own ter­ri­tory after bow­ing. It has been noted that the mate reen­ter­ing the ter­ri­tory will make their ar­rival call and then per­form a slight bow (sim­i­lar to bow de­scribed in ag­gres­sive be­hav­ior) un­less the bird reen­ter­ing is fly­ing in and its part­ner is on a nest. In which case that bird will per­form a seated bow. This ac­tion is thought to be a form of greet­ing. (Schreiber and Nor­ton, 2002; Schreiber and Nor­ton, 2002; Schreiber and Nor­ton, 2002)

• Communication Channels
• visual
• tactile
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Brown boo­bies eat mainly fish. They con­sume most species of fish that are from 5 to 40 cm in length. Ob­served prey in­clude fly­ing fish (Ex­o­coe­tus species), goat fish (Mul­l­i­dae), squir­relfish (Sar­go­cen­tron di­adema), mack­erel (Ras­trel­liger kanagurta), and om­mas­trephid squid (Om­mas­trephi­dae).

To ac­quire food, brown boo­bies use mainly plunge-div­ing. This is where they rise to 10 to 12 m above the water to search for prey be­fore an­gling the body in such a way that it can enter the water as smoothly as pos­si­ble. This po­si­tion changes through­out the dive, start­ing with the ini­tial de­scent. At the time of the de­scent the wings are folded in tightly next to the body, then thrust straight out over their back (prior to en­ter­ing water) until their wings are touch­ing over the cen­ter of their back. De­pend­ing on their al­ti­tude prior to div­ing, they are able to sub­merge them­selves up to 2 m deep. They have also been known to pur­sue prey un­der­wa­ter using a com­bi­na­tion of feet and wing mo­tions.

Along with plunge-div­ing, some fledg­lings (about 1 in 100) and some adults (1 in 500) prac­tice klep­topar­a­sitism, where they steal prey from other seabirds. For ex­am­ple, brown boo­bies have been ob­served steal­ing prey from great frigate­birds (Fre­gata minor) as they trans­fer food to their young. It is thought that fledg­ling frigate­bird calls for food are what at­tracts boo­bies. (Lewis, et al., 2004; Schreiber and Nor­ton, 2002; Yoda, et al., 2007)

• Primary Diet
• carnivore
  • piscivore
  • molluscivore

• Animal Foods
• fish
• mollusks

Pre­da­tion

Sally light­foot crabs (Grap­sus grap­sus) are the only known preda­tors of brown booby hatch­lings. While these crabs mostly for­age around nest­ing sites pick­ing up feath­ers, egg shells, dead chicks, and dry bird ex­cre­ment, they will on very rare oc­ca­sions prey on re­cently hatched chicks that have been ex­pelled from the nest. In these cases, adult birds do noth­ing to pro­tect their young from the crabs and the crabs have never been seen going into the nests after a soli­tary chick. Brown booby young may also be preyed on by larger seabirds and nest­ing colonies may be threat­ened by in­tro­duced preda­tors, such as rats, cats, and pigs. (Gi­anuca and Vooren, 2007)

• Known Predators

  • Sally Lightfoot crabs (Grapsus grapsus)

Ecosys­tem Roles

Richard­son (2006) re­port that the pres­ence of seabird nest­ing colonies (in­clud­ing Sula leuco­gaster on is­lands in­creases the pro­duc­tiv­ity of cer­tain trees (like man­groves) more than is­lands with­out nest­ing colonies. Re­cently, this species, Sula leuco­gaster, has been found to be one of the many con­tribut­ing fac­tors (along with all other nest­ing seabird colonies) to eu­troph­i­ca­tion of the sur­round­ing wa­ters of the is­lands they in­habit. Their nu­tri­ent-rich feces causes lower species di­ver­sity and greater dom­i­nance of mostly epi­phytic biota but also macro-al­gae and phy­to­plank­ton. The rapid growth of the epi­phytes blan­ket the sea grass beds and even­tu­ally causes them to die from lack of sun­light. Any or­gan­ism in the area that de­pended on the sea grass that is un­able to ac­com­mo­date the change will soon die after it. How­ever, no stud­ies have ex­am­ined di­rect ef­fects of eu­troph­i­ca­tion on the nest­ing sea birds from pre­sumed de­clines in fish in the sur­round­ing water.

Brown boo­bies are also host to the par­a­site Babesia poe­lea. Work and Rameyer's (1997) re­search pointed to the pos­si­bil­ity that avian piro­plasms may be species spe­cific and be trans­mit­ted by ar­gasid ticks (Car­ios capen­sis). (Richard­son, 2006)

• Ecosystem Impact
• biodegradation
• parasite

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Ac­cord­ing to Spen­ne­mann (1999), at the turn of the 20th cen­tury brown booby feath­ers were in high de­mand from the Eu­ro­pean and Amer­i­can fash­ion in­dus­try. These feath­ers were used to adorn women's hats and the "take" of such feath­ers led to 2 mil­lion bird deaths (not all Sula leuco­gaster). This de­mand has since died down and reg­u­la­tions are in place to pre­vent over-har­vest­ing for the fash­ion in­dus­try or any other prod­ucts. Sev­eral coun­tries (e.g., Japan and Mada­gas­car) are turn­ing to eco­tourism as a source of in­come and have set aside sev­eral is­lands with very strict reg­u­la­tions to pre­serve the nat­ural en­vi­ron­ment. Ichiki (2003) re­ports that the draw of eco­tourism comes from tourists want­ing to see an­i­mals in their nat­ural en­vi­ron­ment. Con­ve­niently, brown boo­bies nest on these pro­tected is­lands (e.g., Oga­sawara Is­lands, Japan) and its pres­ence be an­other sell­ing point for tourists with an in­ter­est in bird-watch­ing. ("Eco­tourism in Oga­sawara Is­lands", 2003; Spen­ne­mann, 1999)

• Positive Impacts
• body parts are source of valuable material
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of Sula leuco­gaster on hu­mans.

Con­ser­va­tion Sta­tus

Brown boo­bies are not con­sid­ered en­dan­gered at this time and no pro­grams pro­mot­ing their con­ser­va­tion are in progress. Brown booby pop­u­la­tions are con­sid­ered glob­ally sta­ble cur­rently. (Van­der­W­erf, et al., 2007)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Migratory Bird Act

  No special status

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Jason Langteau (au­thor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor), Rad­ford Uni­ver­sity, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

2009. "AnAge Entry for Sula leuco­gaster" (On-line). AnAge's Bib­li­o­graph­i­cal Data­base. Ac­cessed April 12, 2010 at http://​genomics.​senescence.​info/​species/​entry.​php?​species=Sula_​leucogaster.

Oga­sawara Whale-watch­ing As­so­ci­a­tion & Bonin Eco­tourism Com­mis­sion. Eco­tourism in Oga­sawara Is­lands. 100-2101. Japan: Oga­sawara Whale-watch­ing As­so­ci­a­tion & Bonin Eco­tourism Com­mis­sion. 2003. Ac­cessed April 21, 2010 at http://​www.​airies.​or.​jp/​publication/​ger/​pdf/​07-01-03.​pdf.

Bead­ell, J., E. Schreiber, R. Schreiber, G. Schenk, P. Do­herty. 2003. Sur­vival of Brown Boo­bies (Sula leco­gaster) at John­ston Atoll: A long-term study. The Auk, 120(3): 811-817.

Chaves-Cam­pos,, J., J. Tor­res. 2002. Dis­tri­b­u­tion of the Brown Booby (Sula leuco­gaster) in re­la­tion to the in­cli­na­tion of ter­rain. Or­ni­tolo­gia Neotrop­i­cal, 13: 205-208.

Drum­mond, H., C. Ro­driquez, H. Schw­abl. 2008. Do moth­ers reg­u­late fac­ul­ta­tive and ob­lig­ate sib­li­cide by dif­fer­en­tially pro­vi­sion­ing eggs with hor­mones?. Jour­nal of Avian Bi­ol­ogy, 39(2): 139-143.

Gi­anuca, D., C. Vooren. 2007. Abun­dance and be­hav­ior of the sally light­foot crab (Grap­sus grap­sus) in the colony of the Brown Booby (Sula leuco­gaster) in the São Pedro and São Paulo Arch­i­pel­ago. In­ves­ti­ga­ciones Mari­nas, 35(2): 121-125.

Gi­lardi, J. 1992. Sex-spe­cific for­ag­ing dis­tri­b­u­tions of Brown Boo­bies in the east­ern trop­i­cal pa­cific. Colo­nial Wa­ter­birds, 15/1: 148-151.

Lewis, S., E. Schreiber, F. Daunt, G. Schenk, S. Wan­less, K. Hamer. 2004. Flex­i­ble for­ag­ing pat­terns under dif­fer­ent time con­straints in trop­i­cal boo­bies. An­i­mal Be­hav­iour, 68(6): 1331-1337.

Mack, L., A. Larner. 2009. Fall re­port­ing pe­riod Au­gust-No­vem­ber 2008. Vir­ginia Birds, 5(2): 9.

Mellink, E. 2000. Breed­ing of Brown Boo­bies in the Gulf of Cal­i­for­nia: Sea­son­al­ity and ap­par­ent ef­fects of El Nino. Wa­ter­birds: The in­ter­na­tional Jour­ney of Wa­ter­bird Bi­ol­ogy, 23(3): 494-499.

Mellink, E., J. Dominguez, J. Lue­vano. 2001. Diet of east­ern pa­cific Brown Boo­bies Sula leco­gaster brew­steri on Isla San Jorge, north-east­ern Gulf of Cal­i­for­nia, and an April com­par­i­son with diets in the mid­dle Gulf of Gal­i­for­nia. Ma­rine Or­nithol­ogy, 29: 23-28.

Mil­ius, S. 2003. Sib­ling Des­per­ado. Sci­ence News, 163(7): 102.

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