Cathartidae

Diversity

Cathartidae is a family consisting of five extant genera and seven extant species of New World vultures. One of the genera within Cathartidae , Cathartes contains three species ( C. aura , C. burrovianus , and C. melambrotus ), while each of the other four genera consists of only one extant species. Cathartidae are widespread across the new world and all feed on carrion (animal carcasses). All extant Cathartids have unfeathered heads to stay clean while feeding on carrion, and all members have wide wingspans that allow them to soar in search of food. Turkey Vultures ( Cathartes aura ) and Andean Condors ( Vultur gryphus ) are two notable members of this family, as they have remarkable olfactory ability and the largest wingspan of any non-seabird, respectively.

Geographic Range

Cathartids can be found throughout the southern half of the Nearctic Region and through the entirety of the Neotropical Region. They are widespread across this range, though the northern populations do migrate south in the winter. As they are carrion eaters, they do not require specialized habitat types; however, they require roosting areas that limit their areas of distribution.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native

Habitat

Cathartids use thermal air currents to rise and soar vast distances to forage, often encountering many habitat types along the way. As carrion specialists, Cathartids can exist in almost any habitat where carrion is present. They vary in roosting area requirements, with some members such as Turkey Vultures and Black Vultures exploiting a wide variety of roosts (including man-made structures such as power poles), and other, larger members, such as Andean Condors, requiring very specific roosting conditions (cliff roosts with specific climatic variables). Most Cathartids forage for carrion based on sight, but members of the genus Cathartes have a keen sense of smell which allows them to locate carrion that is obscured by foliage or other obstacles.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• chaparral chaparral
• forest forest
• rainforest rainforest
• scrub forest scrub forest
• mountains mountains

• Wetlands
• marsh marsh

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

Systematic and Taxonomic History

Cathartidae is classified within the order Ciconiiformes , which also contains herons, storks, spoonbills, and ibises. This reflects a recent shift in phylogenetic understanding based on genetic evidence, which has shown that similarities between cathartids and old world vultures within the family Accipitiridae are the result of convergent evolution. Cytochrome b has been used as a gene of interest, as well as more recent whole-genome analyses, to understand these relationships better. The family name Cathartidae does not have any taxonomic synonyms.

Physical Description

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Cathartids reach sexual maturity around five or six years old, then mate monogamously (with many species mating for life with one individual). Mating displays are common in birds finding first-year mates and vary between species. In some groups, such as Andean Condors, birds may fight for territories during the breeding season.

• Mating System
• monogamous monogamous
• cooperative breeder cooperative breeder

Cathartids lay a clutch of eggs once per year (though condors lay eggs less frequently than vultures) in the breeding season, which varies based on latitude. They usually lay around 1-3 eggs per clutch and both the male and female watch over the eggs and care for hatchlings. Depending on the species, parents can provide anywhere from almost no assistance to young once they have fledged (as in Cathartes ) or for up to two years after the young hatch. Hatchlings are mostly helpless and parents spend a large amount of time guarding the nest. Some defensive behaviors employed by parents to protect their young are hissing, projectile vomiting, and playing dead.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Within Cathartidae , both parents invest a large amount of time and resources into their offspring, with both males and females defending the nest and providing food for the young. Parental investment varies between species, with vultures caring for their young for less than a year and condors providing extended care for their young, ceasing only when a new clutch of eggs is laid. Most of the parental investment occurs after fertilization has occurred, without much before. Birds in this order do not build elaborate nests but rather find and defend roosts in which to raise chicks.

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

Lifespan/Longevity

The longevity of Cathartidae species is not well understood. Generally, members seem to be long-lived birds which can potentially live as long as seventy years in captivity. Lifespans in the wild are not well studied, especially because many members of Cathartidae die prematurely as a result of lead toxicity. As with many birds, survivorship in Cathartidae is lowest while the birds are developing into full adults. If individuals make it past this critical stage of four to eight years old they are likely to live long lives as adults.

Behavior

Cathartidae species have a wide variety of behaviors. While some of the vultures (Turkey Vultures and Black Vultures) will inhabit large communal roosts, some (such as the Yellow-headed Vultures, King Vultures, and both condors) are generally solitary or are found with only a few other individuals. There are dominance hierarchies that may be determined by age or appearances (such as brilliance of head color in Turkey Vultures) that affect roosting and foraging behaviors. Members of Cathartidae do not usually migrate and will soar in areas surrounding their roost or nest to forage but will return to roosts to sleep. Pair bonding is common in this group and is often life-long or until one mate dies. Most members of Cathartidae engage in sunning behaviors wherein the wings are spread and exposed to sunlight for several minutes at a time.

• Key Behaviors
• flies
• glides
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• colonial colonial
• dominance hierarchies dominance hierarchies

Communication and Perception

Cathartidae members have well-developed eyes which are their primary mechanism for sensing the world around them. Members do not have a syrinx, and thus do not communicate via calls; however, they are capable of grunting and hissing which can be used to signal aggression to other cathartids. More commonly, posturing and display are used to communicate, such as puffing of air sacs or snapping at other individuals with the beak. Hierarchies within and between Cathartidae species keep aggressive behaviors to a minimum, with multiple species being able to interact with each other at the same carcass without fighting. Many species in this group forage by following other species to carcasses instead of finding them on their own. Notably, Turkey Vultures have excellent olfactory abilities, with their olfactory bulbs in the brain being around four times as large as a Black Vulture's. This enhanced sense of smell allows Turkey Vultures to easily locate carcasses, and for other cathartids to follow and take advantage of carcasses that they might have otherwise not sensed.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Cathartids eat carrion nearly exclusively, foraging on vertebrate carcasses as well as invertebrates when available. They will rarely feed on live animals that cannot defend themselves and can rarely kill small organisms to feed. Cathartids are primarily carnivorous, but have been recorded eating plant matter from the digestive systems of carcasses. Cathartids are not choosy about carcasses and will eat from wild and domestic kill alike, including mammals, reptiles, birds, amphibians, fish, and insects. They have also been recording eating rotting plant matter (such as pumpkin) when resources are scarce.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • insectivore insectivore
  • molluscivore molluscivore
  • scavenger scavenger

Predation

Cathartids have few consistent predators. As large-bodied birds, they are only vulnerable to larger birds and nest predators. Eagles killing cathartids at feeding carcasses have been reported but are not common, and there have been reports of predatory mammals predating smaller cathartids at roosting sites. Egg-eating predators such as mongoose and ravens have been seen feeding on their nests. Cathartids most common predator defense is a foul-smelling projectile vomit which is launched at the threatening party. Cathartids also posture and snap with their beaks to keep predators away from their eggs. Currently, humans are the most common predator, with shootings and poisonings common in unprotected species.

Ecosystem Roles

Cathartids are vital in the breakdown of large terrestrial carcasses and have physiological adaptations which break down diseases found in the food they eat. In this way, they keep an ecosystem clean and healthy, while facilitating decomposition which aids in nutrient cycling. The extremely low pH of their stomach allows them to destroy microbes which would sicken other vertebrates, such as anthrax. They carry ectoparasites such as mites and feather lice, but not in significantly higher incidences than other birds.

• Ecosystem Impact
• biodegradation biodegradation

Economic Importance for Humans: Positive

Cathartids do not directly interact with humans but are present in our ecosystems and help clean up unsightly animal corpses. Their ability to breakdown dangerous bacteria such as anthrax also helps limit disease transmission among organisms, including humans. Larger Cathartids, such as California Condors, are of interest to tourists and birdwatchers both due to size and the story of the conservation efforts regarding them. Many have also been prevalent features in folklore and rituals, often representing death.

• Positive Impacts
• ecotourism ecotourism

Economic Importance for Humans: Negative

Cathartids have minimal adverse effects on humans. They will eat from livestock carcasses but do not kill them, and occasionally large groups of vultures will congregate in urban areas and cause slight inconvenience to people. In addition, many find cathartids to be off-putting in terms of appearance and diet.

Conservation Status

Cathartids range from IUCN status of least concern to critically endangered. Smaller cathartids such as Turkey Vultures and Black Vultures have large, stable populations, while California Condors have only a few hundred wild individuals, all descended from 27 captive-bred birds. All cathartids are affected by human activities including hunting, trapping, and poisoning. Hunters who use lead shot to kill off pest species generally do not clean up the carcasses they create, which are then consumed by cathartids, which often results in lead poisoning in the birds. Moreover, a misunderstanding of cathartids has led many humans to trap and kill or intentionally poison the birds in an attempt to keep them from "killing" (as stated above, cathartids do not kill livestock but will feed on their carcasses) their livestock or rummaging through trash that has been left out. Habitat loss has also impacted cathartids, particularly in Central and South America where deforestation for the sake of agriculture and livestock is commonplace.

Additional Links

Encyclopedia of Life

Contributors

Erin Carlson (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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