Animal Diversity Web

Diversity

Tribe Pelecani is within order Pelecaniformes. Pelecani is separated into three families: Pelecanidae, Balaenicipitidae, and Scopidae. Pelecani individuals are distinguished by long necks, articulating vertebrae with a sharp S-bend, large beaks, large body sizes, earth-tone feathers, and large webbed feet. Within family Pelecanidae, there is one genus, Pelecanus, made up of 8 species: P. erythrorhynchos, P. occidentalis, P. thagus, P. onocrotalus, P. conspicillatus, P. rufescens, P. crispus, and P. philippensis. In family Balaenicipitidae, there is one genus, Balaeniceps, made up of one species, B. rex. Lastly, in family Scopidae, there is one genus, Scopus, with one species, S. umbretta. ("Pelecaniformes", 2011; Perrins, 2003)

Geographic Range

Family Pelecanidae is found in most regions around the world and has the widest range compared to the other families in Pelecani. They are found in Nearctic, Neotropical, Ethiopian, Palearctic, and Australian regions. Both the Balaenicipitidae family and the Scopidae family are found only in the Ethiopian region. (Guillet, 1978; Perrins, 2003)

• Biogeographic Regions
• nearctic
  • native
• palearctic
  • native
• ethiopian
  • native
• neotropical
  • native
• australian
  • native

• Other Geographic Terms
• cosmopolitan

Habitat

Pelecanidae inhabit marine and inland waters. They are mainly present in warm regions of the world. Pelecanidae's breeding range spans from latitude 45° south to 60° north. Family Balaenicipitidae inhabit freshwater swamps and are prevalent in dense marshes. Balaenicipitidae are generally nonmigratory birds, with the exceptions of human disturbance, lack of food, and/or habitat disturbance forcing them to relocate. Family Scopidae inhabit all wetland areas, including rivers, streams, estuaries, savannahs, and forests. They require shallow waters. Additionally, Scopidae coexist/inhabit with humans very well. ("Hamerkop, Bird of many Legends", 2018; National, 2015; Perrins, 2003)

• Habitat Regions
• temperate
• tropical
• terrestrial
• saltwater or marine
• freshwater

• Terrestrial Biomes
• savanna or grassland
• chaparral
• forest
• rainforest
• scrub forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools
• coastal
• brackish water

• Wetlands
• marsh
• swamp
• bog

• Other Habitat Features
• urban
• suburban
• agricultural
• riparian
• estuarine

Systematic and Taxonomic History

Pelecani is classified as a tribe/suborder under the order Pelecaniformes, which includes families Pelecanidae, Balaenicipitidae, and Scopidae. Based on recent molecular evidence, Pelecani has undergone a change in phylogenetic understanding. The initial evidence showed that all three families were closely related, with Balaenicipitidae and Scopidae being sister groups to Pelecanidae. The most recent change was related to family Balaencipitidae. They were previously grouped within order Ciconiiformes by the Sibley-Anlquist taxonomy, but after a DNA study in 2008, they were placed within order Pelecaniformes. Scopidae was first described by French zoologist Mathurin Jacques Brisson in 1760. (Anderson, 2020; Kennedy, et al., 2013; Louchart, et al., 2011; Mikhailov, 1995)

Physical Description

Pelecani contains families Pelecanidae, Balaenicipitidae, and Scopidae. Pelecanidae has the extant genus Pelecanus with eight extant species. Balaenicipitidae has the extant genus Balaeniceps with one living species, B. rex. Scopidae has the extant genus Scopus with one living species, S. umbretta. (Campbell and Lack, 1985; Khanna, 2005; Perrins, 2003)

Pelecanidae is recognizable by their large throat pouch that can hold up to 28lbs of water. They are large birds with a weight range of 5.5lbs - 33lbs. In fact, P. onocrotalus and P. crispus are the world's heaviest flying birds. Pelecanidae have a body length ranging between 4.2ft - 5.6ft long. Their wingspan range is between 6.6ft - 9.2ft. They have bright yellow long beaks, webbed feet, and short tail feathers. They have predominately pale plumage, with the exceptions of P. occidentalis, which is brown in color and the smallest species of the family, and P. thagus, which has dark plumage with a white strip running from the top of the head and down the sides of the neck.

Males are larger than the females. The young are downy and are either white, grey, or brown in color. Juveniles get their true plumage at around two months. (Galván, 2008; Khanna, 2005; Perrins, 2003)

Balaenicipitidae are known for their height and prehistoric, stork-like appearance. Their necks are short and thick compared to the other species within Pelecani. They have a weight ranging between 8.8lbs - 15.4lbs. They have a body length ranging between 3.3ft - 4.6ft long. Their wingspan range is between 7.7ft - 8.6ft. Their beak is enormous (reaching up to 9.4in) and is shoe-shaped, gray-ish in color, has a terminal hook, and has erratic gray-ish markings. Their toes are long and divided with no webbing. Balaenicipitidae are blue-gray in color with a dark-green sheen on their dorsal side. The young are predominately brown in color. They are homeothermic and the sexes are alike in color. Males are larger and have longer bills than females. (Galván, 2008; Khanna, 2005; National, 2015; Perrins, 2003)

Scopidae are highlighted by their hammer-shaped heads. They have an average weight of 17oz and body length of 20in. Their average wingspan is 3.0ft. Their beak length is long, ranging from 3.1in - 3.3in, and is hooked at the end. Their tail is short, similar to pelicans (P. thagus). Their feet are different compared to the other two families in this tribe, being only partially webbed. Their middle toe is fringed like herons. They are medium-sized wading birds that have brown plumage with an iridescent purple coloration along their back. The sexes are alike in color and similar in size. Juveniles resemble the adults. (Anderson, 2020; Galván, 2008; "Hamerkop, Bird of many Legends", 2018; Khanna, 2005; Perrins, 2003)

• Sexual Dimorphism
• male larger

Reproduction

Individuals in family Pelecanidae usually breed year-round. Balaenicipitidae only breed once a year during the dry season, and Scopidae's breeding occurs year-round with an increase during the dry season. (Perrins, 2003)

Pelecanidae are monogamous for a single season and only pair at the nest site. In this family, there is a complex communal courtship. In the ground-nesting, white-plumage pelican species P. erythrorhynchos, P. conspicillatus, P. onocrotalus, and P. crispus, males chase females in air, land, and water while they grapple at each other. However, the tree-nesting species P. rufescens, P. philippensis, and P. occidentalis males perch and attract females by displaying their plumage. (Kepler, 1978; Perrins, 2003; Vestjens, 1977)

Balaenicipitidae are monogamous and pair with a single partner each season. Not much is known about the courtship behavior of B. rex, but it is thought they may attract a mate by head-bobbing and clapping their bills. Since they are solitary animals, they do not display group rituals. Both males and females vigorously defend their territories and nest areas from competition and predators. (Mullers and Amar, 2015; National, 2015; Perrins, 2003)

Scopidae are monogamous for life with their partner. S. umbretta has a unique social display that involves false copulation, including mimicking the noises expected in the act, as well as standing on the other individual’s back. S. umbretta is neither colonial nor aggressively territorial because proximity is not a necessity. (Hagemeyer, 2016; Kaweesa, et al., 2013; Perrins, 2003)

• Mating System
• monogamous
• cooperative breeder

Pelecanidae breed year-round and hatch between 1-3 eggs per mating cycle. Balaenicipitidae breed only once a year and hatch between 1-3 eggs per mating cycle. Scopidae breed year-round with their nests containing between 3-7 eggs per mating cycle. (Kepler, 1978; Perrins, 2003; Vestjens, 1977)

The Pelecanidae incubation period ranges between 30 - 36 days and hatchlings weigh around 60g at birth. Pelecanidae nestlings exhibit siblicide, where only one of the nestlings will survive after the first few weeks. The young become fledglings at 10 - 12 weeks. They become sexually mature between the ages of 3 - 4 years. Balaenicipitidae's incubation period averages around 30 days. Although usually only 2 - 3 chicks are hatched, shoebill parents rarely raise more than one chick, making the other chicks "backups" just in case the eldest does not survive. The young become fledglings at around 15 weeks and can fly at 16 weeks. They become sexually mature at the age of 3 years old. Scopidae egg size is highly variable and depends on season, clutch size, and the mother herself. The incubation period takes around 30 days, and due to the 1 - 3 day intervals of being sporadically laid, the eggs hatch asynchronously. The chicks become fledglings at 7 weeks and are independent at 13 weeks. They reach sexual maturity between 18 - 24 months. (Hagemeyer, 2016; "Hamerkop, Bird of many Legends", 2018; Mullers and Amar, 2015; National, 2015; Perrins, 2003)

• Key Reproductive Features
• fertilization
  • internal

Pelecanidae males and females both help with building nests, wherein the males bring the materials (usually in their pouch) and the females build it. Thus, Balaenicipitidae males and females both invest in building the nest and watering the nest, the lattermost being a necessity since they breed during the dry season. Similarly, Scopidae males and females both invest in building the nest. (Mullers and Amar, 2015; Vestjens, 1977)

Tree-nesting Pelecanidae individuals can build a nest as large as 100ft wide. Both males and females incubate the eggs on top of or under their feet, and both sexes invest in feeding the young. The chicks are fed by regurgitation during the first week, then they will put their heads inside their parents' pouches and self-feed after that. At 6 - 8 weeks, the young are able to wander and explore, including swimming a little and starting to feed in group settings. (Mullers and Amar, 2015; Perrins, 2003; Vestjens, 1977)

Balaenicipitidae build their floating nests out of aquatic vegetation. Their nests sit in a cleared area around 8ft wide and are often partially submerged in water, up to 3ft deep. Both parents incubate and guard the eggs/nest, and both invest in feeding the young chicks. The chicks are fed by regurgitation. Since this is a family of early breeders, the chicks have the advantage of longer parental care than other families within Pelecani. (Mullers and Amar, 2015; National, 2015; Perrins, 2003)

The most interesting part about Scopidae is the giant nests compared to the birds' sizes, sitting nearly 5 feet wide with the strength to support the average man’s weight. Often built over the course of 10-14 weeks in a tree and over water, the nest is built with sticks and mud, features a domed roof, a 5in - 7in wide entrance, a 2-foot-long tunnel, and a large nesting chamber. Nest-building happens year-round regardless of breeding and functions as a bonding ritual between the monogamous pair. Unused and unprotected nests will be repurposed by all sorts of animals, and it is possible to see upwards of 600 nests in a 3 square mile area. Incubation is performed primarily by females but is shared between sexes. The length of time spent in the nest for offspring is longer than most birds, indicating stronger parental investment. Both parents invest in feeding the chicks. The parents sometimes leave their young unattended for long periods of time, but the offspring are safe due to the nest's security. ("Hamerkop, Bird of many Legends", 2018; Kaweesa, et al., 2013; Perrins, 2003)

• Parental Investment
• no parental involvement
• altricial
• male parental care
• female parental care
• pre-independence
  • protecting
    • male
    • female
• extended period of juvenile learning

Lifespan/Longevity

The lifespan of Pelecanidae ranges between 10 - 25 years in both the wild and in captivity. In captivity, they tend to live longer, but not significantly so. The longest recorded lifespan in the wild was a brown pelican (P. occidentalis) who lived to 43 years old. The longest recorded lifespan in captivity was 54 years old. The average lifespan of Balaenicipitidae individuals in the wild is 35 years old. The average lifespan in captivity is 50 years old. The lifespan of Scopidae is 10 - 20 years in both the wild and captivity, a longer lifespan compared to other small wading birds. (Campbell and Lack, 1985; Perrins, 2003)

Factors that can limit Pelecanidae's lifespans are disease (most notably infections after being injured by fishing wire/hooks) and siblicide behavior.

Balaenicipitidae lifespans are limited mainly due to habitat loss for agriculture. Another contributing factor is accidental nest destruction by cattle trampling.

The main factor affecting Scopidae's lifespan is egg predation. Only 50% of individuals survive from snake and lizard attacks. Only 30% - 40% of chicks survive predation before they can fly. If a Scopidae individual can survive to adulthood, they have a very strong chance of living past 20 years. (Campbell and Lack, 1985; "Hamerkop, Bird of many Legends", 2018; National, 2015; Perrins, 2003)

Behavior

Pelecanidae are very social birds. They are always found in large colonial groups. They migrate, breed, and feed in social groups and fly in formation.

Balaenicipitidae are never found in groups. They are solitary birds, keep around 20ft apart, and have a foraging territory of around 66ft. Even though they have breeding pairs that are monogamous, they will forage for food at opposite ends of their territory. They are very docile birds and will tend to stay away from humans.

Scopidae are usually solitary birds that will be completely silent when alone but will engage in social courting. (Perrins, 2003)

Pelecanidae are diurnal birds. They are most active in the morning, but during the breeding season, they tend to forage at night. They can overheat and will splash around in the water, expanding and contracting their bill pouches to allow body heat to escape via the bill's blood vessels. (Hainsworth, 1988; Perrins, 2003)

Balaenicipitidae are diurnal and terricolous. They are non-migratory/sessile birds if resources are plentiful. Like pelicans, when Balaenicipitidae overheat, they use gular-fluttering in order to keep cool. Their most interesting behavior is that they can stand completely still for ~30 minutes. They use this behavior as a "lie and wait" hunting strategy. (National, 2015; Perrins, 2003)

Scopidae are diurnal birds that are crepuscular. They tend to limit their movements as much as possible and their territories are dominated by breeding pairs. When a new body of water appears or is located, they will move in quickly. They are soaring birds. Interesting behaviors of Scopidae include the "false mounting" and huge nests they build, which are strong enough to hold a grown man. (Hagemeyer, 2016; "Hamerkop, Bird of many Legends", 2018; Perrins, 2003)

• Key Behaviors
• terricolous
• diurnal
• crepuscular
• sedentary
• solitary
• territorial
• colonial

Communication and Perception

Pelecanidae use visual and tactile cues. Balaenicipitidae use visual cues and engage in both verbal and non-verbal communication. Scopidae use visual cues and engage in verbal communications. (Khanna, 2005; Perrins, 2003)

Pelecanidae populations engage in both verbal and non-verbal communication. They mainly rely on visual and behavioral displays to communicate between conspecifics. They will use their wings and bills to communicate in a non-aggressive or defensive manner. They show aggressive behavior by snapping and thrusting with their bills, or by expanding their wings to make themselves appear larger. Pelecanidae make low grunt sounds and are very vocal when in a colony, especially when it is breeding season, but are relatively silent when alone. Nestlings are also very vocal when the parents are away. (Campbell and Lack, 1985; Perrins, 2003)

Balaenicipitidae are normally silent but will occasionally clatter their bill. This display has been noted to have cow-like, moo-ing sounds as well as high-pitched sounds. Bill-clattering is used by juveniles and adults alike as their primary method of communication. Hiccup-like sounds can also be heard from the nest when nestlings are begging for food. (National, 2015; Perrins, 2003)

When Scopidae are alone, they are silent, but once in groups they become more vocal. They produce a ‘kek’ or ‘yip’ sound in social gatherings. When in flight, they produce a shrill sound. During the breeding season, they perform a courtship ceremony wherein 10 - 20 birds gather and run in circles around each other, flapping their wings and raising/exposing their crests whilst calling out loudly. (Hainsworth, 1988; "Hamerkop, Bird of many Legends", 2018)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Pelecanidae are mainly piscivores, however, they occasionally eat amphibians, crustaceans, insects, birds, and mammals. They can catch multiple fish by scooping them up with their throat pouch. Pelecanidae can expand their throat pouch, drain the water by tilting their head back, and let the water pour out the sides. They can then reposition the fish to swallow it whole, headfirst. Both P. thagus and P. occidentalis individuals usually plunge-dive headfirst to catch prey. P. thagus individuals dive from a height of 33ft - 66ft for anchovies and menhaden, while P. occidentalis dive from lower heights. (Perrins, 2003; Schreiber, 1987)

Balaenicipitidae's diet consists of predominantly aquatic prey like lungfish (Protopterus), tilapia (Tilapia), and watersnakes (Nerodia). They tend to hunt in shallow waters with tall vegetation, which they use as camouflage to stalk prey. They also hunt in waters with low oxygen concentration because the fish must come up for air, which makes them easier to be caught. Balaenicipitidae use two hunting techniques: “lie and wait” and “wade and walk slowly." Once they spot their prey, they pin them with their body and use the end of their sharp-pointed beak to pierce it. (National, 2015; Perrins, 2003; Schreiber, 1987)

Scopidae's diet consists of amphibians and fish, but they are generalists. They hunt by walking around shallow waters for prey and they are able feed during flight. If their prey is dirty with mud or other contaminants, Scopidae will take it to clean water to wash it off. ("Hamerkop, Bird of many Legends", 2018; Perrins, 2003; Schreiber, 1987)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates
  • piscivore
  • insectivore
• omnivore

Predation

When it comes to Pelecanidae, their main predators are cats, coyotes, and humans. There are few predators of adult Pelecanidae, and individuals living on isolated islands have a better chance of survival. Most are able to avoid predation by flying away and staying in large social groups. Cats, coyotes, and humans are common predators to breeding colonies and chicks. However, Pelecanidae's greatest threat is humans due to anthropogenic habitat loss, use of insecticides that are harmful to egg development, and overhunting. (Campbell and Lack, 1985; Perrins, 2003; "American White Pelican", 2002)

Balaenicipitidae have very few predators, given their large size as adults and the fact that they defend their young/nest aggressively. Their most common predators include alligators and humans. (Campbell and Lack, 1985; National, 2015; Perrins, 2003)

There is not much known about the predators of Scopidae. The most significant predation events are suffered by their eggs. Even though their nests are large and well-constructed, about 50% of their eggs are eaten by predators like snakes and monitor lizards. (Campbell and Lack, 1985; "Hamerkop, Bird of many Legends", 2018; Perrins, 2003)

Ecosystem Roles

Pelecanidae, Balaenicipitidae, and Scopidae all play an important role in the food chain. They are notable predators that consume small prey and provide food for scavengers. They also act as hosts for parasites and ticks. Additionally, Scopidae's nests provide habitat/shelter for other animals once abandoned. (Khanna, 2005; Perrins, 2003)

• Ecosystem Impact
• creates habitat

Economic Importance for Humans: Positive

Both Pelecanidae and Balaenicipitidae are sold for consumption by humans. Pelecanidae are hunted for sport while Balaenicipitidae are captured and sold for profit to zoos and private owners. However, all birds in this tribe are unique and majestic, which makes them great for birdwatching and ecotourism. (Campbell and Lack, 1985; "Hamerkop, Bird of many Legends", 2018; Perrins, 2003)

• Positive Impacts
• pet trade
• food
• body parts are source of valuable material
• ecotourism

Economic Importance for Humans: Negative

Pelecanidae sometimes compete with commercial fisherman for food, although the impact on the fishermen's catches is not significant because the birds consume fish that are not typically targeted by fisheries. Both Balaenicipitidae and Scopidae have not shown any adverse effects on humans. (Campbell and Lack, 1985; Perrins, 2003)

Conservation Status

Pelecanidae species range from IUCN's statuses of Least Concern to Near Threatened. P. erythrorhynchos, P. occidentalis, P. onocrotalus, P. conspicillatus, and P. rufescens are listed as Least Concern, while P. thagus, P. crispus, and P. philippensis are listed as Near Threatened. P. occidentalis has the largest number of mature adults at 300,000 and their population numbers are steadily increasing. P. philippensis has the lowest number of mature adults ranging between 8,700 - 12,000 and their numbers are steadily decreasing. Pelecanidae populations are declining due to human activities, including habitat loss due to deforestation, hunting, and pollution. Fishermen not properly collecting and disposing of hooks and fishing lines also causes these birds to be injured, potentially resulting in death. Just the presence of humans in an area can result in temporary or permanent nest abandonment as well. Thankfully, these bird families continue to thrive because of their large ranges. (BirdLife International Pelican, 2016; Crivelli, 1984)

Balaenicipitidae have an IUCN status of Vulnerable. The number of mature adults ranges from 3,300 - 5,300 and their numbers are steadily decreasing. The main reasons for their declines in population include habitat destruction for agriculture, overhunting, and the bird trade. For example, annual breeding success rates have been shown to be as low as 20% in Bangweulu due to human disturbance and chicks being removed from nests. (BirdLife International Shoebill, 2018; Guillet, 1978)

Scopidae's IUCN status is listed as Least Concern. The exact number of mature adults of Scopidae is not known due to the fact that this family is not well-studied, but their population seems to be stable. One of the advantages this family has over the other two is they are able to cohabitate and coexist with humans. (BirdLife International Hamerkop, 2016)

• IUCN Red List [Link]

  Not Evaluated

Other Comments

Family Pelecanidae has existed for at least 30 million years. The oldest fossil was dated during the early Oligocene period in Luberon, France. This fossil was incredibly similar to the birds' modern form, especially the beak.

In ancient Egypt, Pelecanidae was associated with death and the afterlife. In Christianity, they are the symbol of a caring and self-sacrificing parent. (Campbell and Lack, 1985; Kennedy, et al., 2013; Louchart, et al., 2011; "Pelecaniformes", 2011)

Balaenicipitidae have two extinct fossil species from the early Oligicene period. Extinct genera Goliathia and Paludavis fossils were found in Egypt.

Balaeniceps's name was derived from the Latin word balaena for “whale” and caput for “head." (Campbell and Lack, 1985; "Hamerkop, Bird of many Legends", 2018; Mikhailov, 1995; "Pelecaniformes", 2011)

Scopidae were thought to have lived during the Pilocene period. They have one extinct fossil species, S. xenopus, found in South Africa. It was described by ornithologist Storrs Olson in 1984. This extinct species was thought to be larger than its modern counterparts, and based on the shape of the tarus, might have been more aquatic than the extant species, S. umbrette.

Scopus's name was derived from the ancient Greek word skia for “shadow” and from the Latin word umbrette for “umber” or “dark brown." (Anderson, 2020; Campbell and Lack, 1985; "Pelecaniformes", 2011; Perrins, 2003)

Contributors

Valerie Alonso (author), Colorado State University, Audrey Bowman (editor), Colorado State University, Sydney Collins (editor), Colorado State University.

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