Preening (bird)
Preening is a maintenance behaviour found in birds that involves the use of the bill to position their feathers, interlock barbs that have become separated, clean and keep ectoparasites under check.
Etymology
The use of the word "preen" to mean the tidying of a bird's feathers dates from Late Middle English. It appears to be a variant of the word prune; one now obsolete definition of prune meant "annoint", based on the Latin ungere, which had the same meaning. This usage was combined with the Scottish and northern English dialect preen meaning "pierce" or "pin", due to the "pricking" action of the bird's beak during preening.[1]
Importance of preening
Because feathers are critical to a bird's survival — contributing as they do to insulation, waterproofing and aerodynamic flight — birds spend a great deal of time maintaining them.[2] For example, one study found that gulls spend 15% of their daylight hours preening during the breeding season.[3] Preening can be associated with and follow or precede other maintenance behaviours including dusting, bathing, sunning, oiling or anting. Although preening is primarily an individual behaviour, some species indulge in allopreening, with one individual preening another, especially in hard to reach locations. The action of allopreening and its solicitation play roles in establishing hierarchies and in forming bonds within social groups of birds.[4]
Preening action
Preening may involve two kinds of bill actions - nibbling (or mandibulating) while working the feather from base to tip and secondly stroking, either with the bill closed or open. In grebes this is done more vigorously with an open bill and is termed as stropping. In penguins, the head is also used in a motion referred to as wiping. Some birds will also use their feet in an action termed as scratch-preening which is usually applied to the head. Some species (including nightjars, herons, frigatebirds, owls and pratincoles)[5] have comb like serrations on the claw (a pectinate claw) of the middle toe which may aid in scratch preening. While some species use the leg over the lowered head while the wing is held low, others extend the leg between the wing and the body.[6]
Preen oil
Many birds have a preen or uropygial gland opening above the base of the tail feathers. This gland produces a lipid-rich secretion that is applied first to the bill and then to the feathers. The preen gland is absent in the ratites (emu, ostrich, cassowary) as well as some neognath birds, including bustards, a few parrots and pigeons. The gland is large in aquatic birds.[7][8] The uropygial secretion plays a role in reducing the growth of fungi and bacteria. In some cases such as hoopoes there are symbiotic Enterococcus faecalis that prevent the growth of harmful bacteria such as Bacillus licheniformis.[9] During moult, the pinfeathers have sheaths that need to be removed during preening as the feather emerges.[2] Some birds like the herons have special feathers called powder down which breakdown into a fine dust which the birds apply to their contour feathers while preening.[10]
Secondary functions
Preening may serve a secondary function in courtship displays with a role in signalling the health of birds. In Bohemian waxwings, preen oil increased the UV reflectance of feathers.[11] During the breeding season, great white pelicans (Pelecanus onocrotalus) produce a uropygial gland secretion that is orange-red in colour which, on application to the feathers, imparts a pink flush to it. The yellow feathers of a great hornbill (Buceros bicornis) are also cosmetically coloured during preening.[12]
Preening may also be performed as a displacement activity by birds that have been alarmed and are returning to normalcy.[13]
Allopreening
Allopreening is the preening of one bird by another.[6] It is not particularly common among birds,[14] though species from at least 43 families are known to engage in the mutual activity.[15] Most allopreening activity concentrates on the head and neck, with a lesser amount directed towards the breast and mantle and an even smaller percentage applied to the flanks. A few species are also known to allopreen other areas—including rump, tail, belly and underwing.[4]
A number of hypotheses have been advanced to explain the behavior: that it assists in effective grooming, that it assists in recognition of individuals (mates or potential sexual partners), and that it assists in social communication, reducing or redirecting potential aggressive tendencies.[15] These functions are not mutually exclusive.[16] Evidence suggests that different species may participate for different reasons, and that those reasons may change depending on the season and the individuals involved.[15] In most cases, allopreening involves members of the same species, although some cases of interspecific allopreening are known; the vast majority of these involve icterids, though at least one instance of mutual grooming between a black vulture and a crested caracara has been documented.[17] Birds seeking allopreening adopt specific, ritualised postures to signal so; they may fluff their feathers out, for example, or put their heads down.[14]
There is some evidence that allopreening may help to keep in good condition those feathers that a bird cannot easily reach by itself; allopreening activities tend to focus on the head and neck, for example.[18][19] It may also help to remove ectoparasites from those hard-to-reach areas. Allopreening is most common among species that are regularly in close physical contact due to flocking or social behaviours,[14] and such contact allows for easier transfer of ectoparasites between individuals.[20] In one study, Macaroni penguins that frequently allopreened had significantly fewer ticks on their heads and necks than those that did not.[21] Green wood hoopoes, a flocking species with a complex hierarchy, show similar frequencies of initiating and reciprocating allopreening of the head and neck regardless of social status, time of year or group size, which suggests that such activity is primarily related to feather hygiene.[16]
Most allopreening is done between the two members of a mated pair,[6] and the activity appears to play an important role in strengthening and maintaining pair bonds. It is more common in species where both parents help to raise the offspring, and correlates with an increased likelihood that partners will remain together for successive breeding seasons.[20] Allopreening often features as part of the "greeting ceremony" between the members of a pair in species such as albatrosses and penguins, where partners may be separated for a relatively long period of time, and is far more common among species that are sexually monomorphic (that is, species where the sexes look outwardly similar). It appears to inhibit or sublimate aggression, as it is typically the dominant bird that initiates the behaviour.[4]
Allopreening also appears to reduce the incidence of conflict between members of some colonially living or colonially nesting species. For example, neighboring black guillemots that engaged in allopreening were much less likely to fight. Since fights often lead to eggs or chicks being knocked off breeding cliffs, fewer fights led to greater breeding success for allopreening neighbors.[22] Among social flocks of green wood hoopoes, rates of body allopreening (that is, allopreening of another bird's body rather than head and neck) increased with group size. Evidence suggests this type of allopreening reduces social tension, and thus plays an important role in group cohesion. More dominant birds received far more body allopreening services than did lower-ranked birds, and lower-ranked birds initiated far more body allopreening bouts than did their higher-ranked flock mates. Body allopreening was only reciprocal when done with between members of a mated pair; otherwise, the dominant bird reciprocated in fewer than 10% of the instances.[16] Among caged birds, confining a bird with an incompatible or very dominant cage mate can lead to excessive allopreening, which can result in feather plucking or injury.[23]
References
- ↑ "Preen". Oxford English Living Dictionary. Oxford University Press. Retrieved 6 August 2017.
- 1 2 Elphick, Chris; Dunning, Jr., John B. (2001). "Behaviour". In Elphick, Chris; Dunning, Jr., John B. & Sibley, David. The Sibley guide to Bird Life & Behaviour. London: Christopher Helm. pp. 57–59. ISBN 0713662506.
- ↑ Delius, J. D. (May 1988). "Preening and Associated Comfort Behavior in Birds" (PDF). Annals of the New York Academy of Sciences. 525 (1 Neural Mechan): 40–55. doi:10.1111/j.1749-6632.1988.tb38594.x.
- 1 2 3 Harrison, C. J. O. (July 1965). "Allopreening as Agonistic Behaviour". Behaviour. 24 (3): 161–208. ISSN 1568-539X. JSTOR 4533105. doi:10.1163/156853965x00011.
- ↑ Stettenheim, Peter R. (2000-08-01). "The Integumentary Morphology of Modern Birds—An Overview". American Zoologist. 40 (4): 461–477. ISSN 0003-1569. doi:10.1668/0003-1569(2000)040[0461:timomb]2.0.co;2.
- 1 2 3 Campbell, Bruce; Lack, Elizabeth, eds. (1985). A Dictionary of Birds. Carlton, UK: T and A D Poyser. pp. 102–103. ISBN 0-85661-039-9.
- ↑ Haribal, Meena; Dhondt, André A.; Rosane, David; Rodriguez, Eloy (2005). "Chemistry of preen gland secretions of passerines: different pathways to same goal? why?". Chemoecology. 15: 251–260. doi:10.1007/s00049-005-0318-4.
- ↑ Jacob, Jurgen; Ziswiler, Vincent (1982). "The Uropygial Gland". In Farner, D.S.; King, J.R.; Parkes, K.C. Avian Biology. Volume 6. New York: Academic Press. pp. 199–324.
- ↑ Ruiz-Rodríguez, M.; Valdivia, E.; Soler, Juan J.; Martín-Vivaldi, M.; Martín-Platero, A. M.; Martínez-Bueno, M. (2009-11-15). "Symbiotic bacteria living in the hoopoe9s uropygial gland prevent feather degradation". Journal of Experimental Biology. 212 (22): 3621–3626. ISSN 0022-0949. PMID 19880722. doi:10.1242/jeb.031336.
- ↑ Wetmore, Alexander (1920). "The Function of Powder Downs in Herons" (PDF). The Condor. 22 (5): 168–170.
- ↑ Pérez-Rodríguez, Lorenzo; Mougeot, Francois; Bortolotti, Gary R. (2011-07-01). "The effects of preen oils and soiling on the UV–visible reflectance of carotenoid-pigmented feathers". Behavioral Ecology and Sociobiology. 65 (7): 1425–1435. ISSN 0340-5443. doi:10.1007/s00265-011-1153-y.
- ↑ Delhey, Kaspar; Peters, Anne; Kempenaers, Bart (2007-01-01). "Cosmetic Coloration in Birds: Occurrence, Function, and Evolution.". The American Naturalist. 169 (S1): S145–S158. ISSN 0003-0147. doi:10.1086/510095.
- ↑ Iersel, J. J. A. Van; Bol, A. C. Angela (1958-01-01). "Preening of Two Tern Species. a Study On Displacement Activities". Behaviour. 13 (1): 1–87. ISSN 1568-539X. doi:10.1163/156853958x00037.
- 1 2 3 Wilson, Edward O. (2000) [1975]. Sociobiology: The New Synthesis. Cambridge, MA, US: Harvard University Press. pp. 208–209. ISBN 978-0-674-00089-6.
- 1 2 3 Forsman, Eric D.; Wight, Howard M. (July 1979). "Allopreening in Owls: What Are Its Functions?" (PDF). The Auk. 96 (3): 525–531. JSTOR 4085549.
- 1 2 3 Radford, Andrew N.; Du Plessis, Morné A. (December 2006). "Dual Function of Allopreening in the Cooperatively Breeding Green Woodhoopoe, Phoeniculus purpureus". Behavioral Ecology and Sociobiology. 61 (2): 221–230. JSTOR 25511576. doi:10.1007/s00265-006-0253-6.
- ↑ Ng, David; Jasperson, Bruce D. (May 1984). "Interspecific Allopreening between Crested Caracara and Black Vulture" (PDF). The Condor. 86 (2): 214–215. JSTOR 1367047.
- ↑ Loon, Rael; Loon, Hélène (2005). Birds: The Inside Story. Cape Town, South Africa: Struik. p. 36. ISBN 978-1-77007-151-3.
- ↑ Olsen, Penny; Joseph, Leo (2011). Stray Feathers: Reflections on the Structure, Behaviour and Evolution of Birds. Collingwood, VIC, Australia: CSIRO. p. 249. ISBN 978-0-643-09493-2.
- 1 2 Kenny, Elspeth; Birkhead, Tim R.; Green, Jonathan P. (9 June 2017). "Allopreening in birds is associated with parental cooperation over offspring care and stable pair bonds across years". Behavioural Ecology. arx078. doi:10.1093/beheco/arx078.
- ↑ Deeming, D. Charles; Reynolds, S. James, eds. (2015). Nests, Eggs, and Incubation: New ideas about avian reproduction. Oxford, UK: Oxford University Press. p. 94. ISBN 978-0-19-871866-6.
- ↑ Lewis, Sue; Roberts, Gilbert; Harris, Mike P.; Prigmore, Carina; Wanless, Sarah (August 2007). "Fitness increases with partner and neighbour allopreening". Biological Letters. 3 (4): 386–389. PMC 2390679 . doi:10.1098/rsbl.2007.0258.
- ↑ Coles, Brian H., ed. (2007). Essentials of Avian Medicine and Surgery (3rd ed.). Oxford, UK: Blackwood Publishing Ltd. p. 46. ISBN 978-1-4051-5755-1.