Bird of prey

For other uses, see Bird of prey (disambiguation).
Bird of prey
Golden eagle (Aquila chrysaetos)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Family: Several, see text
Griffon vulture

Birds of prey, also known as raptors, hunt and feed on other animals. The term "raptor" is derived from the Latin word rapere (meaning to seize or take by force).[1] These birds are characterized by keen vision that allows them to detect prey during flight and powerful talons and beaks.

Many species of birds may be considered partly or exclusively predatory. However, in ornithology, the term "bird of prey" applies only to birds of the families listed below. Taken literally, the term "bird of prey" has a wide meaning that includes many birds that hunt and feed on animals and also birds that eat very small insects.[2] In ornithology, the definition for "bird of prey" has a narrower meaning: birds that have very good eyesight for finding food, strong feet for holding food, and a strong curved beak for tearing flesh.[3] Most birds of prey also have strong curved talons for catching or killing prey.[3][4] An example of this difference in definition, the narrower definition excludes storks and gulls, which can eat quite large fish, partly because these birds catch and kill prey entirely with their beaks,[2] and similarly bird-eating skuas, fish-eating penguins, and vertebrate-eating kookaburras are excluded. Birds of prey generally prey on vertebrates, which are usually quite large relative to the size of the bird.[2] Most also eat carrion, at least occasionally, and vultures and condors eat carrion as their main food source.[3] Many raptor species are considered apex predators.

Classification

Bald eagle

The order Accipitriformes is inferred to have originated about 44 million years ago when it split from the common ancestor of the secretarybird (Sagittarius serpentarius) and the rest of the accipitrid species.[5] The phylogeny of Accipitriformes is complex and difficult to unravel. Widespread paraphylies were observed in many phylogenetic studies.[6][7][8][9][10] Unfortunately more recent and detailed studies show similar results.[11] However, according to the findings of a 2014 study, the sister relationship between larger clades of Accipitriformes was well supported (e.g. relationship of Harpagus kites to buzzards and sea eagles and these latter two with Accipiter hawks are sister taxa of the clade containing Aquilinae and Harpiinae).[5]

The diurnal birds of prey are formally classified into five families of two orders.

These families were traditionally grouped together in a single order Falconiformes, however are now split into two orders: Falconiformes and Accipitriformes. The Cathartidae are sometimes placed separately in an enlarged stork family (Ciconiiformes), and may be raised to an order of their own (Cathartiiformes).

The secretary bird and/or osprey are sometimes listed as subfamilies of Acciptridae: Sagittariinae and Pandioninae, respectively.

Australia's letter-winged kite is a member of the family Accipitridae, although it is a wholly nocturnal bird.

The nocturnal birds of prey – the owls – are classified separately as members of two extant families of the order Strigiformes:

Historical classifications

The taxonomy of Carl Linnaeus grouped birds (class Aves) into orders, genera and species, with no formal ranks between genus and order. He placed all birds of prey into a single order, Accipitres, subdividing this into four genera: Vultur (vultures), Falco (eagles, hawks, falcons, etc.), Strix (owls), and Lanius (shrikes). This approach was followed by subsequent authors such as Gmelin, Latham, and Turnton.

Louis Pierre Veillot used additional ranks: order, tribe, family, genus, species. Birds of prey (order Accipitres) were divided into diurnal and nocturnal tribes; the owls remained monogeneric (family Ægolii, genus Strix), whilst the diurnal raptors were divided into three families: Vulturini, Gypaëti, and Accipitrini.[12]

Thus Veillot's families were similar to the Linnaean genera, with the difference that shrikes were no longer included amongst the birds of prey. In addition to the original Vultur and Falco (now reduced in scope), Veillot adopted four genera from Savigny: Phene, Haliæetus, Pandion, and Elanus. He also introduced five new genera of vultures (Gypagus, Catharista, Daptrius, Ibycter, Polyborus)[note 1] and eleven new genera of accipitrines (Aquila, Circaëtus, Circus, Buteo, Milvus, Ictinia, Physeta, Harpia, Spizaëtus, Asturina, Sparvius).

Common names

The common names for various birds of prey are based on structure, but many of the traditional names do not reflect the evolutionary relationships between the groups.

Variations in shape and size

Many of these English-language group names originally referred to particular species encountered in Britain. As English-speaking people travelled further, the familiar names were applied to new birds with similar characteristics. Names that have generalized this way include: kite (Milvus milvus), sparrow-hawk or sparhawk (Accipiter nisus), goshawk (Accipiter gentilis), kestrel (Falco tinninculus), hobby (Falco subbuteo), harrier (simplified from "hen-harrier", Circus cyaneus), buzzard (Buteo buteo).

Some names have not generalized, and refer to single species (or groups of closely related (sub)species): merlin (Falco columbarius), osprey (Pandion haliaetus).

Migration

Migratory behaviour evolved multiple times within accipitrid raptors.

An obliged point of transit of the migration of the birds of prey is the bottleneck-shaped Strait of Messina, Sicily, here seen from Dinnammare mount, Peloritani.

The earliest event occurred nearly 14–12 million years ago. This result seems to be one of the oldest dates published so far in the case of birds of prey.[5] For example, a previous reconstruction of migratory behaviour in one Buteo clade[10] with a result of the origin of migration around 5 million years ago was also supported by that study.

Migratory species of raptors had a southern origin because it seems that all of the major lineages within Accipitridae had an origin to one of the biogeographic realms of the Southern Hemisphere. The appearance of migratory behaviour occurred in the tropics parallel with the range expansion of migratory species to temperate habitats.[5] Similar results of southern origin in other taxonomic groups can be found in the literature.[13][14][15]

Distribution and biogeographic history highly determine the origin of migration in birds of prey. Based on some comparative analyses, diet breadth also has an effect on the evolution of migratory behaviour in this group,[5] but its relevance needs further investigations. The evolution of migration in animals seems to be a complex and difficult field with many unanswered questions.

Sexual dimorphism

Raptors are known to display patterns of sexual dimorphism. It is commonly believed that the dimorphisms found in raptors occur due to sexual selection or environmental factors. In general, hypotheses in favor of ecological factors being the cause for sexual dimorphism in raptors are rejected. This is due to the fact that the ecological model is less parsimonious, meaning that its explanation is more complex than that of the sexual selection model. Additionally, ecological models are much harder to test for due to the fact that a great deal of data is required.[16]

Dimorphisms can also be the product of intrasexual selection between males and females. It appears that both genders of the species play a role in the sexual dimorphism within raptors; females tend to compete with other females to find good places to nest and attract males, and males competing with other males for adequate hunting ground so they appear as the most healthy mate.[17] It has also been proposed that sexual dimorphism is merely the product of disruptive selection, and is merely a stepping stone in the process of speciation, especially if the traits that define gender are independent across a species. Sexual dimorphism can be viewed as something that can accelerate the rate of speciation. [18]

In non-predatory birds, males are typically larger than females. However, in birds of prey, the opposite is the case. For instance, take into account the kestrel, a type of falcon in which males are the primary providers, and the females are responsible for nurturing the young. In this species, the smaller kestrels are, the less food is needed and thus, they can survive in environments that are harsher. This is particularly true in the male kestrels. It has become more energetically favorable for male kestrels to remain smaller than their female counterparts because of the fact that smaller males have an agility advantage when it comes to defending the nest and hunting. Larger females are favored because they can incubate larger numbers of offspring, while also being able to breed a larger clutch size.[19]

See also

Notes

  1. ↑ Veillot included the caracaras (Daptrius, Ibycter, and Polyborus) in Vulturini, though we now know that they are related to falcons.

References

  1. ↑ Brown, Leslie (1997). Birds of Prey. Chancellor Press. ISBN 1-85152-732-X.
  2. 1 2 3 Burton, Philip (1989). Birds of Prey. illustrated by Boyer, Trevor; Ellis, Malcolm; Thelwell, David. Gallery Books. p. 8. ISBN 0-8317-6381-7.
  3. 1 2 3 Perrins, Christopher, M; Middleton, Alex, L. A., eds. (1984). The Encyclopaedia of Birds. Guild Publishing. p. 102.
  4. ↑ Fowler, D.W., Freedman, E.A., & Scannella, J.B. (2009). "Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique". PLoS ONE 4 (11): e7999. doi:10.1371/journal.pone.0007999. PMC 2776979. PMID 19946365.
  5. 1 2 3 4 5 Nagy, J.; Tökölyi, J. (2014). "Phylogeny, historical biogeography and the evolution of migration in accipitrid birds of prey (Aves: Accipitriformes)" (PDF). Ornis Hungarica 22 (1): 15–35. doi:10.2478/orhu-2014-0008.
  6. ↑ Motta-Junior, et. al. (eds.) (2004). Raptors worldwide (PDF). Berlin: WWGBP. pp. 483–498.
  7. ↑ Helbig, A. J.; Kocum, A.; Seibold, I.; Braun, M. J. (2005). "A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level". Molecular Phylogenetics and Evolution 35 (1): 147–164. doi:10.1016/j.ympev.2004.10.003.
  8. ↑ Lerner, H. R. L.; Mindell, D. P. (2005). "Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA" (PDF). Molecular Phylogenetics and Evolution 37 (2): 327–346. doi:10.1016/j.ympev.2005.04.010. PMID 15925523.
  9. ↑ Griffiths, C. S.; Barrowclough, G. F.; Groth, J. G.; Mertz, L. A. (2007). "Phylogeny, diversity, and classification of the Accipitridae based on DNA sequences of the RAG-1 exon". Journal of Avian Biology 38 (5): 587–602. doi:10.1111/j.2007.0908-8857.03971.x.
  10. 1 2 do Amaral, F. R., et. al. (2009). "Patterns and processes of diversification in a widespread and ecologically diverse avian group, the buteonine hawks (Aves, Accipitridae)" (PDF). Molecular Phylogenetics and Evolution 53 (3): 703–715. doi:10.1016/j.ympev.2009.07.020.
  11. ↑ Breman, F. C., et. al. (2013). "DNA barcoding and evolutionary relationships in Accipiter Brisson, 1760 (Aves, Falconiformes: Accipitridae) with a focus on African and Eurasian representatives.". Journal of Ornithology 154 (1): 265–287. doi:10.1007/s10336-012-0892-5.
  12. ↑ Veillot, Louis Pierre (1816). Saunders, Howard, ed. Analyse d'une nouvelle ornithologie élémentaire. (in French) (London 1883 ed.). Willughby Society.
  13. ↑ Joseph, L.; Lessa, E. P.; Christidis, L. (1999). "Phylogeny and biogeography in the evolution of migration: shorebirds of the Charadrius complex". Journal of Biogeography 26 (2): 329–342. doi:10.1046/j.1365-2699.1999.00269.x.
  14. ↑ Outlaw, D. C., et. al. (2003). "Evolution of long-distance migration in and historical biogeography of Catharus thrushes: a molecular phylogenetic approache". The Auk 120: 299–310. doi:10.1642/00048038(2003)120[0299:EOLMIA]2.0.CO;2.
  15. ↑ Milá, B.; Smith, T. B.; Wayne, R. K. (2006). "Postglacial population expansion drives the evolution of long–distance migration in a songbird". Evolution 60 (11): 2403–2409. doi:10.1111/j.0014-3820.2006.tb01875.x. PMID 17236431.
  16. ↑ Mueller, H.C. ". The Evolution of Reversed Sexual Dimorphism in Owls: An Empirical Analysis of Possible Selective Factors". The Wilson Bulletin 98 (3): 387–406.
  17. ↑ Wiehn, J.; Korpimakki, E.; Massemin, S. (2000). "Reversed sexual size dimorphism in raptors: evaluation of the hypotheses in kestrels breeding in a temporally changing environment". Oecologia. 12426-32.
  18. ↑ BOLNICK, David; DOEBEL, Michael (November 2003). "SEXUAL DIMORPHISM AND ADAPTIVE SPECIATION: TWO SIDES OF THE SAME ECOLOGICAL COIN". The society of evolution 57 (11).
  19. ↑ Sonerud, G; Steen, R; Low, L; Roed, L.; Skar, K.; Selas, V; Slagsvold, T (2013). "Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors". Oceologa 172 (1): 93–107. doi:10.1007/s00442-012-2491-9.

Further reading

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