Editing Seabird (section)

=== Adaptations to life at sea ===
Seabirds have made numerous adaptations to living on and feeding in the sea. [[Wing]] morphology has been shaped by the [[ecological niche|niche]] an individual species or family has [[evolution|evolved]], so that looking at a wing's shape and [[wing loading|loading]] can tell a scientist about its life feeding behaviour. Longer wings and low wing loading are typical of more [[pelagic]] species, while diving species have shorter wings.<ref name="Gaston">Gaston, Anthony J. (2004). ''Seabirds: A Natural History'' New Haven:Yale University Press, {{ISBN|0-300-10406-5}}</ref> Species such as the [[wandering albatross]], which forage over huge areas of sea, have a reduced capacity for powered flight and are dependent on a type of [[Gliding flight|gliding]] called [[dynamic soaring]] (where the wind deflected by waves provides lift) as well as slope soaring.<ref>{{cite journal|author=Pennycuick, C. J. |year=1982|title=The flight of petrels and albatrosses (Procellariiformes), observed in South Georgia and its vicinity|journal=[[Philosophical Transactions of the Royal Society B]] |volume=300|pages=75–106|doi=10.1098/rstb.1982.0158|issue=1098|bibcode=1982RSPTB.300...75P|doi-access=free}}</ref> Seabirds also almost always have [[Bird feet and legs#Webbing and lobation|webbed feet]], to aid movement on the surface as well as assisting diving in some species. The [[Procellariiformes]] are unusual among birds in having a strong [[olfaction|sense of smell]], which is used to find widely distributed food in a vast ocean,<ref>{{cite journal|author1=Lequette, B. |author2=Verheyden, C. |author3=Jowentin, P. |year=1989|title=Olfaction in Subantarctic seabirds: Its phylogenetic and ecological significance|journal=The Condor |volume=91|pages=732–735|url=http://sora.unm.edu/sites/default/files/journals/condor/v091n03/p0732-p0735.pdf|doi=10.2307/1368131|issue=3|jstor=1368131 }}</ref> and help distinguish familiar nest odours from unfamiliar ones.<ref>{{cite journal|last1=Mitkus|first1=Mindaugas|last2=Nevitt|first2=Gabrielle A.|last3=Kelber|first3=Almut|date=2018|title=Development of the Visual System in a Burrow-Nesting Seabird: Leach's Storm Petrel|url=https://doi.org/10.1159/000484080|journal=Brain, Behavior and Evolution|language=en|volume=91|issue=1|pages=4–16|doi=10.1159/000484080|pmid=29212065|s2cid=4964467|issn=0006-8977|access-date=March 15, 2021|via=Karger|url-access=subscription}}</ref>

[[File:Phalacrocorax-auritus-007.jpg|thumb|left|Cormorants, like this [[double-crested cormorant]], have plumage that is partly wettable. This functional adaptation balances the competing requirement for [[thermoregulation]] against that of the need to reduce buoyancy.<ref name=JAB2005>{{cite journal|author1=Grémillet, D. |author2=Chauvin, C. |author3=Wilson, R. P. |author4=Le Maho, Y. |author5=Wanless, S. |year=2005|title= Unusual feather structure allows partial plumage wettability in diving great cormorants ''Phalacrocorax carbo''|journal=Journal of Avian Biology |volume=36 |issue=1 |pages= 57–63|doi=10.1111/j.0908-8857.2005.03331.x}}</ref>]]

[[Supraorbital gland|Salt glands]] are used by seabirds to deal with the [[Edible salt|salt]] they ingest by drinking and feeding (particularly on [[crustacean]]s), and to help them [[osmoregulation|osmoregulate]].<ref name="Harrison">Harrison, C. S. (1990) ''Seabirds of Hawaii, Natural History and Conservation'' Ithaca:Cornell University Press, {{ISBN|0-8014-2449-6}}</ref> The [[excretion]]s from these glands (which are positioned in the head of the birds, emerging from the [[nasal cavity]]) are almost pure [[sodium chloride]].<ref name="Schmidt-Nielson">{{cite journal |last1=Schmidt-Nielson|first1=Knut |date=May 1960 |title= The Salt-Secreting Gland of Marine Birds |journal=Circulation |volume=21 |issue=5 |pages=955–967 |doi= 10.1161/01.CIR.21.5.955 |pmid=14443123 |doi-access=free }}</ref>

With the exception of the [[cormorant]]s and some terns, and in common with most other birds, all seabirds have waterproof [[plumage]]. However, compared to land birds, they have far more feathers protecting their bodies. This dense plumage is better able to protect the bird from getting wet, and cold is kept out by a dense layer of [[down feather]]s. The cormorants possess a layer of unique feathers that retain a smaller layer of air (compared to other diving birds) but otherwise soak up water.<ref name=JAB2005/> This allows them to swim without fighting the [[buoyancy]] that retaining air in the feathers causes, yet retain enough air to prevent the bird losing excessive heat through contact with water.<ref name="King233">{{cite book |last=King |first=Richard J. |date=2013 |title=The Devil's Cormorant: A Natural History |location=Durham, NH |publisher=University of New Hampshire Press |page=233 |isbn=978-1-61168-699-9}}</ref>

The plumage of most seabirds is less colourful than that of land birds, restricted in the main to variations of black, white or grey.<ref name="Gaston" /> A few species sport colourful plumes (such as the tropicbirds and some penguins), but most of the colour in seabirds appears in the bills and legs. The plumage of seabirds is thought in many cases to be for [[camouflage]], both defensive (the colour of [[United States Navy|US Navy]] [[battleship]]s is the same as that of [[Antarctic prion]]s,<ref name="Gaston" /> and in both cases it reduces visibility at sea) and aggressive (the white underside possessed by many seabirds helps hide them from prey below). The usually black wing tips help prevent wear, as they contain melanins that help the feathers resist abrasion.<ref name="Elphick2016">{{cite book|last=Elphick|first=Jonathan|year=2016|publisher=Firefly Books|title=Birds: A Complete Guide to their Biology and Behavior|location=Buffalo, New York|isbn=978-1-77085-762-9|page=80}}</ref>