Editing Louse (section)

==Ecology==
The average number of lice per host tends to be higher in large-bodied bird species than in small ones.<ref>{{cite journal | vauthors = Rózsa  | year = 1997| title = Patterns in the abundance of avian lice (Phthiraptera: Amblycera, Ischnocera) | url = http://www.zoologia.hu/list/patterns%20in%20the%20abundance.pdf | journal = Journal of Avian Biology | volume = 28 | issue = 3| pages = 249–254 | doi=10.2307/3676976| jstor = 3676976}}</ref> Lice have an aggregated distribution across bird individuals, i.e. most lice live on a few birds, while most birds are relatively free of lice. This pattern is more pronounced in territorial than in colonial—more social—bird species.<ref>{{cite journal | vauthors = Rékási J, Rozsa L, Kiss BJ | year = 1997 | title = Patterns in the distribution of avian lice (Phthiraptera: Amblycera, Ischnocera) | url = http://www.zoologia.hu/list/patterns%20in%20the%20distribution.pdf | journal = Journal of Avian Biology | volume = 28 | issue = 2| pages = 150–156 | doi=10.2307/3677308 | jstor = 3677308 | citeseerx = 10.1.1.506.730 }}</ref> Host organisms that dive under water to feed on aquatic prey harbour fewer taxa of lice.<ref>{{cite journal | vauthors = Felsõ B, Rózsa L | title = Reduced taxonomic richness of lice (Insecta: Phthiraptera) in diving birds | journal = The Journal of Parasitology | volume = 92 | issue = 4 | pages = 867–9 | date = August 2006 | pmid = 16995408 | doi = 10.1645/ge-849.1 | s2cid = 31000581 }}</ref><ref>{{cite journal | vauthors = Felső B, Rózsa L | year = 2007 | title = Diving behaviour reduces genera richness of lice (Insecta: Phthiraptera) of mammals | url = http://www.zoologia.hu/list/felso_rozsa2.pdf | journal = Acta Parasitologica | volume = 52 | pages = 82–85 | doi=10.2478/s11686-007-0006-3| s2cid = 38683871 }}</ref> Bird taxa that are capable of exerting stronger antiparasitic defence—such as stronger [[T cell]] immune response or larger [[uropygial gland]]s—harbour more taxa of Amblyceran lice than others.<ref>{{cite journal | vauthors = Møller AP, Rózsa L | title = Parasite biodiversity and host defenses: chewing lice and immune response of their avian hosts | journal = Oecologia | volume = 142 | issue = 2 | pages = 169–76 | date = January 2005 | pmid = 15503162 | doi = 10.1007/s00442-004-1735-8 | s2cid = 12992951 | bibcode = 2005Oecol.142..169M }}</ref><ref>{{cite journal | vauthors = Møller AP, Erritzøe J, Rózsa L | title = Ectoparasites, uropygial glands and hatching success in birds | journal = Oecologia | volume = 163 | issue = 2 | pages = 303–11 | date = June 2010 | pmid = 20043177 | doi = 10.1007/s00442-009-1548-x | s2cid = 11433594 | bibcode = 2010Oecol.163..303M }}</ref> Reductions in the size of host populations may cause a long-lasting reduction of louse taxonomic richness,<ref name=Rozsa1993>{{cite journal | vauthors = Ròzsa L | title = Speciation patterns of ectoparasites and "straggling" lice | journal = International Journal for Parasitology | volume = 23 | issue = 7 | pages = 859–64 | date = November 1993 | pmid = 8314369 | doi = 10.1016/0020-7519(93)90050-9 }}</ref> for example, birds introduced into [[New Zealand]] host fewer species of lice there than in Europe.<ref>{{cite journal | vauthors = Paterson AM, Palma RL, Gray RD | year = 1999 | title = How Frequently Do Avian Lice Miss the Boat? Implications for Coevolutionary Studies | journal = Systematic Biology | volume = 48 | pages = 214–223 | doi=10.1080/106351599260544 | doi-access = free }}</ref><ref>{{cite journal | vauthors = MacLeod CJ, Paterson AM, Tompkins DM, Duncan RP | title = Parasites lost - do invaders miss the boat or drown on arrival? | journal = Ecology Letters | volume = 13 | issue = 4 | pages = 516–27 | date = April 2010 | pmid = 20455925 | doi = 10.1111/j.1461-0248.2010.01446.x | bibcode = 2010EcolL..13..516M }}</ref> Louse sex ratios are more balanced in more social hosts and more female-biased in less social hosts, presumably due to the stronger isolation among louse subpopulations (living on separate birds) in the latter case.<ref>{{cite journal | vauthors = Rózsa L, Rékási J, Reiczigel J | year = 1996 | title = Relationship of host coloniality to the population ecology of avian lice (Insecta: Phthiraptera) | url = http://www.zoologia.hu/list/relationship%20of%20host%20coloniality.pdf | journal = Journal of Animal Ecology | volume = 65 | issue = 2| pages = 242–248 | doi=10.2307/5727 | jstor = 5727 | bibcode = 1996JAnEc..65..242R }}</ref> The extinction of a species results in the extinction of its host-specific lice. Host-switching is a random event that would seem very rarely likely to be successful, but [[speciation]] has occurred over evolutionary time-scales so it must be successfully accomplished sometimes.<ref name=Rozsa1993/>

Lice may reduce host life expectancy if the infestation is heavy,<ref>{{cite journal | vauthors = Brown CR, Brown MB, Rannala B | year = 1995 | title = Ectoparasites reduce long-term survivorship of their avian host | url = http://www.rannala.org/reprints/1995/Brown1995a.pdf | journal = Proceedings of the Royal Society of London B | volume = 262 | issue = 1365| pages = 313–319 | doi=10.1098/rspb.1995.0211| s2cid = 13869042 }}</ref> but most seem to have little effect on their host. The habit of dust bathing in [[Chicken|domestic hens]] is probably an attempt by the birds to rid themselves of lice.<ref name=Capinera/> Lice may transmit microbial diseases and [[helminth]] parasites,<ref>{{cite journal | vauthors = Barlett CM |year=1993 |title=Lice (''Amblycera'' and ''Ischnocera'') as vectors of ''Eulimdana'' spp. (Nematoda: Filarioidea) in Charadriiform birds and the necessity of short reproductive periods in adult worms |journal=Journal of Parasitology |volume=75 |issue=1 |pages=85–91  |jstor=3283282 |doi=10.2307/3283282}}</ref> but most individuals spend their whole life cycle on a single host and are only able to transfer to a new host opportunistically.<ref name=Capinera/> Ischnoceran lice may reduce the [[thermoregulation]] effect of the plumage; thus heavily infested birds lose more heat than others.<ref>{{cite journal | vauthors = Booth DT, Clayton DH, Block BA | year = 1993 | title = Experimental demonstration of the energetic cost of parasitism in free-ranging hosts | url = http://darwin.biology.utah.edu/PubsHTML/PDF-Files/18.pdf | journal = Proceedings of the Royal Society of London B | volume = 253 | issue = 1337 | pages = 125–129 | doi = 10.1098/rspb.1993.0091 | bibcode = 1993RSPSB.253..125B | s2cid = 85731062 | access-date = 2010-08-14 | archive-url = https://web.archive.org/web/20100610162227/http://darwin.biology.utah.edu/PubsHTML/PDF-Files/18.pdf | archive-date = 2010-06-10 | url-status = dead }}</ref> Lice infestation is a disadvantage in the context of sexual rivalry.<ref>{{cite journal | vauthors = Clayton | year = 1990 | title = Mate choice in experimentally parasitized rock doves: lousy males lose | url = http://darwin.biology.utah.edu/PubsHTML/PDF-Files/11.pdf | journal = American Zoologist | volume = 30 | issue = 2 | pages = 251–262 | doi = 10.1093/icb/30.2.251 | access-date = 2010-08-14 | archive-url = https://web.archive.org/web/20100610164747/http://darwin.biology.utah.edu/PubsHTML/PDF-Files/11.pdf | archive-date = 2010-06-10 | url-status = dead | doi-access = free }}</ref><ref>{{cite journal | vauthors = Garamszegi LZ, Heylen D, Møller AP, Eens M, De Lope F | year = 2005 | title = Age-dependent health status and song characteristics | journal = Behavioral Ecology | volume = 16 | issue = 3| pages = 580–591 | doi=10.1093/beheco/ari029 | doi-access = free }}</ref>