Editing Bird nest (section)

=== Cup ===
<!-- [[Cup nest]] redirects to this heading. -->
[[File:Heliothryx barroti on nest.jpg|thumb|Like many small birds, the [[purple-crowned fairy]] uses considerable amounts of [[spider silk]] in its cup nest.]]
The ''cup'' nest is smoothly hemispherical inside, with a deep depression to house the eggs. Most are made of pliable materials—including grasses—though a small number are made of [[mud]] or [[saliva]].{{sfn|Hansell |2000|p=[https://archive.org/details/birdnestsconstru0000hans/page/280 280]}} Many [[passerine]]s and a few non-passerines, including some [[hummingbird]]s and some swifts, build this type of nest.

[[File:Turdus merula Nesting.jpg|thumb|left|Cup nest of a [[common blackbird]]]]
Small bird species in more than 20 passerine families, and a few non-passerines—including most hummingbirds, kinglets and crests in the genus ''[[Regulus (bird)|Regulus]]'', some [[tyrant flycatcher]]s and several [[New World warbler]]s—use considerable amounts of [[spider silk]] in the construction of their nests.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=445}}</ref><ref name=Erickson>{{Citation |last=Erickson |first=Laura |title=The Wonders of Spider Silk |journal=BirdScope |date=Spring 2008 |volume=22 |issue=2 |pages=7}}</ref> The lightweight material is strong and extremely flexible, allowing the nest to mold to the adult during incubation (reducing heat loss), then to stretch to accommodate the growing nestlings; as it is sticky, it also helps to bind the nest to the branch or [[leaf]] to which it is attached.<ref name=Erickson/>

{{multiple image|total_width=350|footer=Museum specimen of a [[blue-grey gnatcatcher]] cup nest, made with lichens, hair, and spiderwebs.|image1=Blue gray gnatcatcher nest, side 2016-01-07-17.24 (24438660975).jpg|width1=5360|height1=3840|image2=Blue gray gnatcatcher nest, top 2016-01-07-17.39 (24330333612).jpg|width2=5248|height2=3904}}
[[File:Bird nest on a tree.jpg|thumb|278x278px|A bed nest on a tree]]
Many swifts and some hummingbirds{{sfn|Gould |Gould |2007|p=200}} use thick, quick-drying saliva to anchor their nests. The [[chimney swift]] starts by dabbing two globs of saliva onto the wall of a chimney or tree trunk. In flight, it breaks a small twig from a tree and presses it into the saliva, angling the twig downwards so that the central part of the nest is the lowest. It continues adding globs of saliva and twigs until it has made a crescent-shaped cup.{{sfn|Gould |Gould |2007|p=196}}

Cup-shaped nest insulation has been found to be related to nest mass,<ref name="Kern 1984 455–466">{{Citation|last=Kern|first=M|title=Racial differences in nests of white-crowned sparrows|journal=Condor|year=1984|volume=86|issue=4|pages=455–466|doi=10.2307/1366826|jstor=1366826}}</ref><ref name="Heenan 2011">{{Citation|last1=Heenan|first1=Caragh|last2=Seymour |first2=R.|title=Structural support, not insulation, is the primary driver for avian cup-shaped nest design|journal=[[Proceedings of the Royal Society B]]|year=2011|doi=10.1098/rspb.2010.2798|pmid=21325330|volume=278|issue=1720|pages=2924–2929|pmc=3151712}}</ref> nest wall thickness,<ref name="Heenan 2011"/><ref name="Skowron 1980 816–824">{{Citation|last1=Skowron|first1=C|last2=Kern|first2=M.|title=The insulation in nests of selected North-American songbirds|journal=Auk|year=1980|volume=97|issue=4|pages=816–824|doi=10.1093/auk/97.4.816}}</ref><ref>{{Citation|last1=Whittow |first1=F.N.|last2=Berger |first2=A.J.|title=Heat loss from the nest of the Hawaiian honeycreeper, 'Amakihi'|journal=Wilson Bulletin|year=1977|volume=89|pages=480–483}}</ref> nest depth,<ref name="Kern 1984 455–466"/><ref name="Heenan 2011"/> nest weave density/porosity,<ref name="Kern 1984 455–466"/><ref name="Skowron 1980 816–824"/><ref name="Kern 1984 443–454">{{Citation|last1=Kern|first1=M. D.|last2=Van Riper|first2=C.|title=Altitudinal variations in nests of the Hawaiian honeycreeper Hemignathus virens virens|journal=Condor|year=1984|volume=86|issue=4|pages=443–454|doi=10.2307/1366825|jstor=1366825}}</ref> surface area,<ref name="Heenan 2011"/> height above ground<ref name="Kern 1984 455–466"/> and elevation above sea level.<ref name="Kern 1984 443–454"/>

[[File:Процесс строительства гнезда.WebM|thumb|A pair of [[long-tailed tit]]s in the process of building a nest]]
More recently, nest insulation has been found to be related to the mass of the incubating parent.<ref name="Heenan 2011"/> This is known as an [[allometric]] relationship. Nest walls are constructed with an adequate quantity of nesting material so that the nest will be capable of supporting the contents of the nest. Nest thickness, nest mass and nest dimensions therefore correlate with the mass of the adult bird.<ref name="Heenan 2011"/> The flow-on consequence of this is that nest insulation is also related to parent mass.<ref name="Heenan 2011"/>

[[File:Nest 013.jpg|thumb|Hanging bird nest]]