Brown pelican

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Brown pelican
Brown pelican of the subspecies P. o. Californicus

Brown pelican of the subspecies P. o. Californicus

Systematics
Class : Birds (aves)
Order : Pelecaniformes
Family : Pelicans (Pelecanidae)
Genre : Pelicans ( pelecanus )
Type : Brown pelican
Scientific name
Pelecanus occidentalis
Linnaeus , 1766

The Brown Pelican ( Pelecanus occidentalis ), also Brown Pelican or - more rarely - sea pelican called, is a large water bird , which is native to the coasts of North, Central and South America and to the family of pelicans belongs (Pelecanidae).

Brown pelicans are excellent swimmers, but walking on land appears awkward. Their long wings make brown pelicans extremely persistent and graceful fliers, and groups of brown pelicans can often be seen flying in formations just above the water surface.

From a total of eight pelican species Brown Pelican is common with the - closely related to him -  Chile Pelican ( P. thagus ) the only one in the swooping dives into the water to carry off the fish. In addition, both species are also the only ones among the pelicans that are found exclusively in marine waters and have a predominantly dark plumage color.

In the 1970s, the brown pelican was placed under protection in the United States after the build-up of pesticides - especially DDT - in the food chain disrupted the animals' metabolism and resulted in thin-shelled eggs with a high rate of destruction. Due to the protective measures and the ban on DDT in 1972, the stocks have recovered to such an extent that the species is now classified as not endangered by the IUCN .

The brown pelican is the official state bird of the US state Louisiana and is depicted in the Louisiana Seal feeding three chicks.

features

Build and color

Juvenile brown pelican at Bodega Bay , California

When fully grown, brown pelicans reach a body length of 1.00 to 1.37 meters with a wingspan of around 2 meters. The length of their beak is 25 to 38 centimeters, with the beak of males being around 10% longer than that of females. With a body weight of 2 to 4 kilograms, brown pelicans are lighter and slimmer than other pelican species. Male brown pelicans are around 15–20% heavier than female individuals.

Young animals can be recognized by their predominantly brown plumage with a white belly. Brown pelicans reach their final color when they are around 3 to 5 years old. The color of the plumage and other body parts of adult animals changes fundamentally over the course of the year. Some characteristics for each season are:

body part winter spring late summer
Beak (proximal) pale pink, orange bluish-gray, pale pink Gray
Throat sac (distal) dark gray green blue-black-gray dark green
Forehead and crown pale yellow dark yellow-orange white with dark spots
Hood White dark brown reddish brown
Back and wing covers silver gray silver gray matt brown
Upper chest gray-brown dark brown spotted, dull brown
Orbital ring gray pink pink Gray
iris light sky blue light sky blue brown
Legs and feet dark gray black black

Flight image and locomotion

Adult brown pelican in flight at Bodega Head , California
Juvenile brown pelican in flight at Bodega Head

On land and in shallow water, brown pelicans move forward in a staggering and seemingly awkward gait, alternately shifting their weight from one leg to the other. In slow gait they lay their wings on the body, while in faster movements they spread their wings away from the body to keep their balance.

When taking off from the water, the animals lift their upper body so that their wings do not touch the surface of the water. By pushing the legs at the same time, they give themselves an additional boost. During take-off, they stretch their head forward, whereas during flight their head is placed back against the shoulders. The animals usually start their flight movement against the wind.

In flight, groups of brown pelicans form a V formation or fly in a row. Wing beats alternate with gliding. When flying over the sea, the birds often glide close to the surface of the water in order to save energy through the buoyancy of the ground effect .

When landing, brown pelicans spread their tail feathers and stretch both legs forward. Your feet with splayed toes serve as runners when landing on the water. Landings are made at a steeper angle than on water.

While swimming on the water, brown pelicans alternately move their legs. In this way they manage to hold their position even with tidal currents of 6 to 10 km per hour.

Vocalizations

The only vocal utterance of adults is a hoarse "Hrraa-hrraa", which is heard by both sexes on the nest as a reaction to movements of other individuals and occurs especially during the early courtship. Nestlings call out with a high-pitched, croaking sound when they beg for food.

Instrumental sounds occur in connection with agonistic behavior . With their jaws, brown pelicans produce a popping sound when attacked, which is amplified by their elastic skin sac in the lower beak.

distribution and habitat

Distribution of the brown pelican:
  • Outside the breeding season
  • All year round

    • Brown pelicans live on the coasts of both American continents. On the Pacific Ocean the breeding area extends from Northern California to Chile , on the Atlantic Ocean from South Carolina to Venezuela and includes the West Indies . Outside the breeding season, brown pelicans are seen from Canada to Tierra del Fuego .

    Different behaviors are assumed with regard to the migration of brown pelicans. While the populations of the northern Gulf of Mexico are presumably true to their location due to the mild winter temperatures that prevail in the region, the populations further north - such as those from South Carolina - migrate south towards the end of the year, and then return to theirs in late winter and spring Return to breeding colonies. The populations in Florida show a similar dependence of the migration pattern on the respective weather conditions . When cold fronts arrive , the brown pelicans leave the west coast of Florida and move to regions further south outside the United States.

    The brown pelican and its close relative, the chile pelican ( P. thagus ), are the only pelican species that can only be found on the coast of the sea. They are rarely found inland. Brown pelicans prefer flat sea sections or bays and avoid the open sea. For breeding, the brown pelican prefers flat and hardly overgrown islands or dry coastal areas. During the breeding season, the animals rarely move more than 20 km from land to take advantage of the food available in the shallower coastal waters. In addition, brown pelicans are often found near harbors where they feed on fishing waste.

    Way of life

    Food acquisition and food

    Brown pelican in shock diving

    Among the pelicans, the brown pelican, together with the chile pelican, is one of the only species that mainly prey on their food by diving. When searching for food, it spies its prey from the air and then dives into the water from a height of up to 20 meters with flared wings. In the downward movement, the brown pelican turns slightly to the left, presumably to protect the trachea and esophagus on the right side of the neck upon impact. As soon as the beak hits the surface of the water, the bird puts its legs and wings backwards so that the movement towards the prey is not slowed down. At the same time, air cushions in the abdominal area reduce the force of the impact and prevent the brown pelican from being completely immersed in the water. This means that only those prey animals are available to the animals that they can reach with their head and beak below the surface of the water. When the beak is dipped into the water, the prey is brought between the upper and lower jaws and the beak is then closed. The water that is also absorbed in this way is transported out of the beak by turning the head when surfacing, so that only the prey remains in the throat pouch.

    A 1987 study on the likelihood of success of the technique used by the brown pelicans to acquire food showed that the frequency of a successful prey dive increased linearly in proportion to the age of the animals. The research suggests that more experienced animals usually begin the dive at a higher altitude and hit the water at a lesser angle. In addition, brown pelicans seem to avoid the reflection of the sun on the water surface by turning away from the sun during the dive.

    The diet of the brown pelican consists mainly of fish - especially American anchovies ( Engraulis mordax ) and Pacific sardines ( Sardinops sagax ), on the south-eastern coast of the United States 90–95% of Atlantic menhades ( Brevoortia tyrannus ) -, sometimes also of invertebrates . The animals prefer relatively shallow sections of the sea in which the water depth is up to 150 meters. Studies in California have shown that the foraging of brown pelicans is closely tied to those marine areas in which upwelling transports nutrient-rich deep water to higher layers, which leads to a comparatively high food supply. There is a direct connection between the available food supply and the breeding success of the animals.

    Social and territorial behavior

    Group of brown pelicans on a boat off the coast of Trinidad .

    Brown pelicans are sociable year-round birds that breed, sleep, fly, and forage in groups. The largest breeding colonies of brown pelicans in the Gulf of California number five to ten thousand nests; the average size of breeding colonies in the United States is 141 nests. The animals often nest near other species that have similar demands on the habitat, such as gulls , herons , boobies or cormorants .

    Brown pelicans usually flee when predators approach . If they spot mammals as a potential attacker early enough, the animals respond with a threatening gesture by standing up, stretching their beak and finally flapping their wings. If the approach continues, brown pelicans flee. Nesting animals flee from birds of prey that circling above the nest and return to the nest after a while or land on a nearby body of water. On the other hand, brown pelicans rarely show defensive behavior towards nest predators. Seagulls flying close to the nest are driven away with their beak.

    Fighting between brown pelicans is extremely rare. Individual distance between individuals and territorial demarcation are achieved by fast forward movements of the 6–10 centimeter open beak and popping sounds made with the jaws.

    Reproduction and breeding

    Nestlings on the edge of Chesapeake Bay in Maryland

    At the beginning of the breeding season, males occupy breeding sites that they consider suitable. They usually do not leave these places until a suitable female is found. While waiting, the male brown pelicans show a characteristic swinging of the head, in which the head and the opened beak are moved in a loop that traces the shape of the infinity sign. The average waiting time for the female animals is between two and four days, but in individual cases it can be up to three weeks.

    The collection of the nesting material is carried out exclusively from male brown pelicans, while the female animals take care of building the nest. The nest can either be on the ground or in trees, with tree nests usually being made in or near the treetop. The construction time for a nest is between seven and ten days, with individual breeding pairs completing their nest in four days.

    The first egg is usually laid within one to three days after the nest is completed. The average clutch size is three eggs. There are 24 to 64 hours between the individual laying of eggs.

    Both parent birds incubate the eggs, alternating in shifts of several hours. The incubation takes place through the webbing of the parent animals - the brown pelicans stand on their eggs during the incubation process. The breeding season for the Californian brown pelican ( P. o. Californicus ) is between 29 and 32 days.

    In the first seven to ten days of the nestlings' life, their parents provide them with pre-digested and choked up food. Later, the chicks take fish from the beak of their parent birds.

    Diseases, predators and causes of mortality

    Two brown pelicans of the subspecies californicus on a rock at Bodega Head, California

    The nest predators of the brown pelicans include the yellow-legged gull ( Larus livens ), black-headed gull ( Chroicocephalus ridibundus ), herring gull ( Larus argentatus ), Dominican gull ( Larus dominicanus ), crow ( Corvus ossifragus ) and common raven ( Corvus corax ). Dominican gulls, yellow-legged gulls, ravens, bald eagles ( Haliaeetus leucocephalus ) and wood storks ( Mycteria americana ) hunt for nestlings . Among the mammals, raccoons ( Procyon lotor ), house cats ( Felis catus ) and house dogs ( Canis lupus familiaris ) belong to the nest predators.

    First-born nestlings of the brown pelican often kill their siblings either directly by pecking with their beak or indirectly by preventing them from eating or pushing them out of the nest. According to a 1992 Florida study, 30% of nestling deaths were from direct exposure to firstborns and another 28% from indirect exposure to firstborns.

    Due to their size, adult brown pelicans have only a few predators; the capture of adult birds by other animals is rarely observed. Bald eagles have been spotted killing two nesting brown pelicans in a breeding colony in Georgia . Adult brown pelicans swimming on the water are occasionally attacked by sharks or maned seals ( Otaria flavescens ).

    Little is known about the life expectancy of brown pelicans. Ralph W. Schreiber and Patrick J. Mock assume after an evaluation of ringed birds in North Carolina , South Carolina and Florida an average lifespan of 4 to 7 years, with the most common deaths occurring during the migration of the animals and mainly affecting young animals. 30% of the individuals ringed as nestlings and juveniles alone reached an age of more than 12 months and less than 2% reached an age of 10 years. The longest life span recorded to date was achieved by a brown pelican found dead 43 years after being ringed .

    Slightly more than half of the deaths that Schreiber and Mock evaluated and clearly assignable were due to human causes, with the most common cause of death being entanglement in fishing nets or being shot down by hunters. The remaining deaths were due to natural causes such as predators, disease and starvation.

    Systematics

    Research history and taxonomy

    Representation of a brown pelican by John James Audubon . Hand-colored panel from his Birds of America , published between 1827 and 1838 .

    The classification of the brown pelican was unclear for a long time. Carl von Linné led all pelicans up to the tenth edition of his work Systema Naturae under the species name Pelecanus onocrotalus . It was not until the twelfth edition of the Systema Naturae published in 1766 that Linné described the brown pelican as an independent species under the name Pelecanus occidentalis . In his new edition of Linnés Systema Natura from 1789, the German naturalist Johann Friedrich Gmelin summarized the Chilepelican ( P. thagus ), which is now regarded as an independent species, with the Brown Pelican as a species. In his published work in 1884 The Water Birds of North America , described Robert Ridgway P. o. Californicus first time as a subspecies. According to his own statement, Alexander Wetmore recognized around 1925 together with his colleague Charles W. Richmond that the brown pelicans of the island of Hispaniola had to belong to a separate subspecies due to their smaller size, but did not publish his observations. James L. Peters distinguished the subspecies occidentalis , carolinensis , californicus and thagus in his Check-list of Birds of the World published in 1931 . The now generally accepted distinction between the subspecies of the Brown Pelican is based on Wetmore's article A Review of the Forms of the Brown Pelican , published in 1945 . J. Bryan Nelson, in his 2006 volume Pelicans, Cormorants, and their Relatives, questioned the independence of the urinator subspecies , and George R. Angehr and James A. Kushlan suspected in 2007, due to differences in physique and behavior, that it was in the brown pelicans is a separate subspecies in the Gulf of Panama .

    External system

    The brown pelican belongs to the eight species of the monotypic family of pelicans (Pelecanidae). It is closely related to the chilepelican ( P. thagus ), which was initially considered a subspecies of P. occidentalis . Due to its larger body size, differences in plumage color and the fact that the brown pelican and the chile pelican do not mate in overlapping areas of distribution on the Pacific coast of South America, it has been assumed that two separate species have been found since 2007 . Recent genetic studies confirm the sister group relationship . With the methods of the molecular clock a splitting ( allopatric speciation ) results about 0.77 million years ago, with a methodical fluctuation range of 0.64 to 1.54 million years. Due to their darker plumage, their exclusively marine habitat and the shock diving method practiced only by these two species, it has already been suggested several times that P. thagus and P. occidentalis are more closely related than all other subspecies and thus a special position in the family of Ingesting Pelecanidae . According to genetic analyzes, the closest related species is the rhinoceros pelican , so that all New World species form a clade .

    Internal system

    Based on Wetmore's study from 1945, a distinction is made between five subspecies , which differ mainly in their plumage color, the color of the beak and their body dimensions.

    subspecies Initial description Dimensions Features and distribution
    P. o. Occidentalis Linnaeus , 1766 Blades: ♀ 448–486 mm, ♂ 461–496 mm;
    Tail: 114–128 mm, ♂ 114–130 mm;
    Beak: ♀ 251–286 mm, ♂ 255–306 mm;
    Tarsus: 58–77 mm, ♂ 68–78 mm     		Nominate form ; the smallest of the subspecies; similar in color to carolinensis , but with darker plumage on the underside during the breeding season and often with darker plumage on the upper side outside the breeding season; breeds in the Bahamas , the Greater and Lesser Antilles , and along the coasts of Colombia , Venezuela, and Trinidad and Tobago .
    P. o. Carolinensis JF Gmelin , 1789 Sash: ♀ 483–528 mm, ♂ 500–550 mm;
    Tail: ♀ 122–153 mm, ♂ 123–158 mm;
    Beak: ♀ 280–333 mm, ♂ 280–348 mm;
    Tarsus: 68–84 mm, ♂ 70–89 mm     		Larger than occidentalis and smaller than californicus ; during the breeding season with lighter plumage on the underside than occidentalis ; breeds on the east coast of the United States from South Carolina to Texas as well as in Honduras , Costa Rica and Panama ; distributed outside the breeding season from southern New York to Venezuela.
    P. o. Californicus Ridgway , 1884 Sash: ♀ 483–569 mm, ♂ 520–585 mm;
    Tail: 130-200 mm, ♂ 131-198 mm;
    Beak: ♀ 298–330 mm, 316–372 mm;
    Tarsus: 70–83 mm, ♂ 76–89 mm     		On average larger than carolinensis and during the breeding season with significantly darker, sometimes almost black plumage in the neck area and a reddish colored throat pouch; breeds along the Pacific coast in the southwestern United States and northwestern Mexico ; distributed outside the breeding season along the Pacific coast to British Columbia in Canada and south to Guatemala , rarely in El Salvador .
    P. o. Murphyi Wetmore , 1945 Blades: ♀ 478–494 mm, ♂ 505–526 mm;
    Tail: 123–175 mm, 127–162 mm;
    Beak: ♀ 289–297 mm, ♂ 310–346 mm;
    Tarsus: ♀ 61–76 mm, ♂ 69–81 mm     		About the same size as carolinensis , but with darker plumage on top; smaller than californicus and with lighter plumage on the underside; smaller than urinator and with lighter plumage on the underside; breeds from Colombia to Ecuador ; outside of the breeding season also found in northern Peru .
    P. o. Urinator Wetmore, 1945 Sash: ♀ 516–546 mm, ♂ 552–570 mm;
    Tail: ♀ 129-145 mm, ♂ 130-148 mm;
    Beak: ♀ 307–372 mm, ♂ 340–379 mm;
    Tarsus: ♀ 77–85 mm, ♂ 82–89 mm     		Similar to californicus , but with a blackish throat pouch and darker plumage on the back; native to the Galapagos Islands alone .

    Existence and endangerment

    Brown pelican (subspecies P. o. Carolinensis ) in Florida

    The brown pelican was the impetus for the introduction of essential instruments of species protection in the United States . The establishment of the first National Wildlife Refuge in Florida in 1903 already served to protect the species. The main cause of the threat to the brown pelican in the late 19th and early 20th centuries was the strong demand for bird feathers, which were used to decorate women's hats. After the emergence of bird protection organizations such as the Audubon Society and their publicity campaigns began to rethink and the demand for bird feathers declined, the brown pelican fishery threatened a new threat during the First World War . The United States military supplied its soldiers with large quantities of canned sardines, thereby depriving the brown pelicans of one of their food sources. When the sardine stocks finally declined, fishermen set about killing brown pelicans by the thousands because they saw them as competitors in the exploitation of the fish stocks.

    Since 1970, brown pelicans have been protected nationwide in the United States under the Endangered Species Conservation Act , a law that became part of the Endangered Species Act in 1973. The main reason was the risk from the accumulation of pesticides , especially DDT , in the food chain, which disrupted the animals' metabolism and led to thin-shelled eggs. This, and the fact that brown pelicans stand with their feet on the eggs during the brood, led to the destruction of the clutches in the late 1950s and 1960s. The previously important breeding colonies in Texas and Louisiana disappeared completely, the number of brown pelicans in California fell dramatically and larger colonies of the animals remained in Florida alone. Before the protective measures came into effect, the population of brown pelicans in the United States was thus significantly decimated.

    After DDT was banned in 1972 and a series of successful reintroduction efforts, populations recovered to the point in 1985 that the species was removed from federal lists and under jurisdiction in Georgia, Florida, South Carolina, and the coastal Alabama region individual states could be returned. In November 2009, the US Fish and Wildlife Service was also able to lift federal protection in the rest of the range, in particular the Pacific coast in California, the Gulf coast in Louisiana and Texas, as well as the Caribbean islands under US sovereignty.

    The total population of the brown pelican is estimated by Wetlands International to be an approximate value of 350,000 to 400,000 individuals. This number should be handled with caution, as the information on the individual subspecies comes from different years and is partly based on rough estimates. For californicus, by far the most numerous subspecies, the most exact numbers are available. A study published in 2013 comes to a number of around 195,900 ± 7,200 individuals for 2006, whereby the authors of the study assume that this number is likely to be too high, as the population is affected by environmental influences such as the El Niño weather phenomenon and an increasing Loss of breeding areas is influenced by agriculture and tourism. The following population figures are assumed for the other subspecies (the year of the estimate in brackets): carolinensis 120,000 (1999), murphyi 20,000–60,000 (2011), occidentalis 4,930–18,400 (2006/2007) and urinator 5,000 (no year).

    In view of the geographically wide distribution area and the comparatively high population figures, the brown pelican is now classified by the IUCN as "not endangered" ( least concern ). The recovery of the brown pelican population is now regarded as an outstanding example of successful species protection.

    literature

    • Mark Shields: Brown Pelican (Pelecanus occidentalis) , revised July 15, 2014, in: The Birds of North America Online, ed. by A. Poole, Ithaca 2012.
    • Bryan Nelson : Brown Pelican (Pelecanus occidentalis). In: Ders .: Pelicans, Cormorants, and their Relatives. The Pelecaniformes. Oxford 2005, ISBN 0-19-857727-3 , pp. 277-288. (In his review from 2008, Anthony W. Diamond explicitly advises against using the measurement tables in the appendix; Elizabeth A. Schreiber criticizes the sparse information on the brown pelican in comparison to other species descriptions contained in the volume.)

    Web links

    Commons : Brown Pelican  - Album with pictures, videos and audio files

    Individual evidence

    1. ↑ On this and the following cf. Mark Shields, Brown Pelican (Pelecanus occidentalis) , section " Distinguishing Characteristics ", in: The Birds of North America Online, ed. by A. Poole, Ithaca 2012.
    2. ↑ Here reproduced in simplified form. For a detailed description cf. Ralph W. Schreiber et al., Plumages and molts of Brown Pelicans , Natural History Museum of Los Angeles County, Contributions in Science 402 (1989), p. 4.
    3. ↑ On this and on the following - unless otherwise stated - Ralph W. Schreiber, Maintenance Behavior and Communication in the Brown Pelican , Ornithological Monographs 22 (1977), pp. 25-28.
    4. ^ F. Reed Hainsworth, Induced drag savings from ground effect and formation flight in Brown Pelicans , in: The Journal of Experimental Biology 135 (1988), pp. 431-444.
    5. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 27.
    6. ↑ a b c d e Shields, Brown Pelican (Pelecanus occidentalis) , section “Behavior”.
    7. ↑ a b Shields, Brown Pelican (Pelecanus occidentalis) , section " Sounds ".
    8. ↑ On this and the following BirdLife International 2012, Pelecanus occidentalis , The IUCN Red List of Threatened Species. Version 2014.3. Last accessed on January 24, 2015.
    9. ^ Scott T. Walter / Michael R. Carloss / Thomas J. Hess / Giri Athrey / Paul L. Leberg, Movement Patterns and Population Structure of the Brown Pelican , in: The Condor 115, 4 (2013), pp. 788-799 , here p. 789.
    10. ↑ Ralph W. Schreiber / Patrick J. Mock, Eastern Brown Pelicans: What Does 60 Years of Banding Tell Us? , in: Journal of Field Ornithology 59, 2 (1988), pp. 171-182, here p. 177.
    11. ↑ Ralph W. Schreiber / Elizabeth Anne Schreiber, Use of Age-Classes in Monitoring Population Stability of Brown Pelicans , in: The Journal of Wildlife Management 47, 1 (1983), pp. 105–111, here p. 109.
    12. ↑ Kenneth T. Briggs et al., Brown Pelicans in Central and Northern California , in: Journal of Field Ornithology 54, 4 (1983), pp. 353-373, here p. 363f.
    13. ↑ a b c d Shields, Brown Pelican (Pelecanus occidentalis) , section " Food habits ".
    14. ↑ Ralph W. Schreiber et al., Prey Capture by the Brown Pelican , in: The Auk 92, 4 (1975), pp. 649-654, here p. 651.
    15. ^ Frank Richardson, Functional Aspects of the Pneumatic System of the California Brown Pelican , in: The Condor 41, 1 (1939), pp. 13-17, here p. 16.
    16. ↑ Schreiber et al., Prey Capture by the Brown Pelican , pp. 653f.
    17. ↑ On this and the following Robert A. Carl, Age-Class Variation in Foraging Techniques by Brown Pelicans , in: The Condor 89, 3 (1987), pp. 525-533, here pp. 529-532.
    18. ↑ Kenneth T. Briggs et al., Brown Pelicans in Central and Northern California , pp. 369f.
    19. ^ Daniel W. Anderson / Franklin Gress / Kenneth F. Mais, Brown Pelicans: Influence of Food Supply on Reproduction , in: Oikos 39, 1 (1982), pp. 23-31, here, pp. 29f.
    20. ↑ On this and the following - unless otherwise stated - Shields, Brown Pelican (Pelecanus occidentalis) , section " Behavior ".
    21. ↑ E. Velarde / DW Anderson, Conservation and management of seabird islands in the Gulf of California: setbacks and successes , in: DN Nettleship / J. Burger / M. Gochfeld (eds.), Seabirds on islands: threats, case studies and action plans, Cambridge 1994, pp. 229-243, cited here from Shields, Brown Pelican (Pelecanus occidentalis), section “Behavior”.
    22. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 36.
    23. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , pp. 33f.
    24. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 34.
    25. ↑ On this and the following - unless otherwise stated - Schreiber, Maintenance Behavior and Communication in the Brown Pelican , pp. 36-50.
    26. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 36.
    27. ↑ Shields, Brown Pelican (Pelecanus occidentalis) , section " Breeding ".
    28. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 40.
    29. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 40.
    30. ↑ DW Anderson / JJ Hickey, Oological data on egg and breeding characteristics of Brown Pelicans , in: Wilson Bulletin 82 (1970), pp. 14-28, here p. 15.
    31. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 47.
    32. ↑ D. Pinson / H. Drummond, Brown Pelican Siblicide and the Prey-Size Hypothesis , in: Behavioral Ecology and Sociobiology 32, 2 (1993), pp. 111-118, here p. 112.
    33. ^ Schreiber, Maintenance Behavior and Communication in the Brown Pelican , p. 47.
    34. ↑ Bonnie Jean Ploger, Proximate and ultimate causes of brood reduction in Brown Pelicans (Pelecanus occidentalis) , Dissertation, University of Florida, Gainesville 1992, here cited from Shields, Brown Pelican (Pelecanus occidentalis), section “ Demography ”.
    35. ^ Schreiber / Mock, Eastern Brown Pelicans: What Does 60 Years of Banding Tell Us? , P. 171.
    36. ↑ a b Schreiber / Mock, Eastern Brown Pelicans: What Does 60 Years of Banding Tell Us? , P. 178.
    37. ↑ a b Schreiber / Mock, Eastern Brown Pelicans: What Does 60 Years of Banding Tell Us? , P. 176.
    38. ↑ Summarizing the state of research up to 1945 Wetmore, A Review of the Forms of the Brown Pelican , p. 577.
    39. ↑ Linné, Systema Naturae , 12th edition, Volume 1, Stockholm 1766, p. 215.
    40. ^ SF Baird / TM Brewer / R. Ridgway, The Water Birds of North America , Volume 2, Boston 1884, p. 143.
    41. ^ A b Alexander Wetmore, A Review of the Forms of the Brown Pelican , in: The Auk 62, 4 (1945), pp. 577-586, here p. 577.
    42. ↑ James Lee Peters, Check-list of Birds of the World , Volume 1, Cambridge 1931, p. 81.
    43. ↑ J. Bryan Nelson, Pelicans, Cormorants, and Their Relatives: The Pelecaniformes , Oxford 2006, here quoted from Shields, Brown Pelican (Pelecanus occidentalis) , section “ Systematics ”.
    44. ↑ George R. Angehr / James A. Kushlan, Seabird and colonial wading bird nesting in the Gulf of Panama , in: Waterbirds 30, 3 (2007), pp. 335-357, here p. 351.
    45. ↑ On this and on the following - unless otherwise stated - Shields, Brown Pelican (Pelecanus occidentalis) , section “ Systematics ”.
    46. ↑ See Alvaro Jaramillo, Separate Pelecanus thagus from P. occidentalis ( Memento of June 28, 2010 in the Internet Archive ) , Proposal (# 271) to South American Classification Committee of May 2007.
    47. ↑ a b Martyn Kennedy / Scott A. Taylor / Petr Nádvorník / Hamish G. Spencer, The phylogenetic relationships of the extant pelicans inferred from DNA sequence data , in: Molecular Phylogenetics and Evolution 66, 1 (2013), pp. 215-222 . doi : 10.1016 / j.ympev.2012.09.034
    48. ↑ For example Paul A. Johnsgard, Cormorants, Darters, and Pelicans of the World , Washington, DC 1993 and JB Nelson, Pelicans, cormorants and their relatives: The Pelecaniformes , Oxford 2006, here cited from Shields, Brown Pelican (Pelecanus occidentalis) , "Systematics" section.
    49. ^ Wetmore, A Review of the Forms of the Brown Pelican , pp. 578-585.
    50. ↑ a b c Karen Benzel, In harms way. Endangered Brown Pelicans face uncertain future ( Memento February 14, 2015 in the Internet Archive ) , via the International Bird Rescue Research Center, last accessed on January 24, 2015.
    51. ↑ Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye, Plume Trade , 1988, via Stanford Birds, last accessed January 24, 2015.
    52. ↑ Ralph W. Schreiber, The Brown Pelican: An Endangered Species? , in: BioScience 30, 11 (1980), pp. 742-747, here p. 742.
    53. ↑ On the historical development of the population in the United States and the protection and re-naturalization measures in the 1960s, cf. Ralph W. Schreiber / Robert W. Risebrough, Studies of the Brown Pelican , in: The Wilson Bulletin 84, 2 (1972), pp. 119-135.
    54. ↑ US Fish and Wildlife Service, Brown Pelican Delisting Question and Answers from 2008.
    55. ↑ Brown Pelican Populations Recovered, Removed from Endangered Species List , US Fish and Wildlife Service press release, November 11, 2009.
    56. ^ A b Wetlands International, Waterbird Population Estimates , online database, as of January 21, 2015.
    57. ↑ DW Anderson et al., Size and distribution of the California Brown Pelican metapopulation in a non-ENSO year , in: Marine Ornithology 41 (2013), pp. 95-106, here p. 100.
    58. ↑ Anderson et al., Size and distribution of the California Brown Pelican metapopulation , pp. 102f.
    59. ↑ BirdLife International 2012, Pelecanus occidentalis , The IUCN Red List of Threatened Species, Version 2014.3, last accessed January 24, 2015.
    60. ^ "Once a symbol of the detrimental effects of pollution in marine ecosystems, the Brown Pelican now symbolizes the success of wildlife-conservation efforts.", Shields, Brown Pelican (Pelecanus occidentalis) , section " Introduction ".
    61. ↑ Anthony W. Diamond, Pelicans, cormorants, and their relatives: the Pelecaniformes (by JB Nelson) , in: Marine Ornithology 36, 2 (2008), pp. 200-201, here p. 201.
    62. ^ Elisabeth A. Schreiber, Pelicans, Cormorants, and Their Relatives: The Pelecaniformes (by J. Bryan Nelson) , in: The Auk 124, 4 (2007), pp. 1466–1468, here p. 1467.
    This version was added to the list of articles worth reading on February 2, 2015 .