Editing Loon (section)

===Reproduction===
Loons nest during the summer on freshwater lakes and/or large ponds. Smaller bodies of water (up to 0.5&nbsp;km<sup>2</sup>) will usually only have one pair. Larger lakes may have more than one pair, with each pair occupying a bay or section of the lake. The red-throated loon, however, may nest colonially, several pairs close together, in small Arctic [[Tarn (lake)|tarns]] and feed at sea or in larger lakes, ferrying the food in for the young.<ref name=Sjolander1972/><ref name=Sjolander1976/>

Loons mate on land, often on the future nest site, and build their nests close to the water, preferring sites that are completely surrounded by water such as islands or emergent vegetation. Loons use a variety of materials to build their nests including aquatic vegetation, pine needles, leaves, grass, moss and mud. Sometimes, nest material is almost lacking. Both male and female build the nest and incubate jointly for 28 days. If the eggs are lost, the pair may re-nest, usually in a different location. Since the nest is very close to the water, rising water may induce the birds to slowly move the nest upwards, over a metre.<ref name=Sjolander1972/><ref name=Sjolander1976/>

<gallery>
Gavia immer -Osgood Pond, New York, USA -nest-8a.jpg|Common loon on the nest
Juvenile red throated diver.jpg|Juvenile red-throated loon
feedingtime.jpg|Common loon feeding its young
Immature loon with crayfish.jpg|Immature common loon with crayfish
</gallery>

Despite the roughly equal participation of the sexes in nest building and incubation, analysis has shown clearly that males alone select the location of the nest. This pattern has the important consequence that male loons, but not females, establish significant site-familiarity with their territories that allows them to produce more chicks there over time. Sex-biased site-familiarity might explain, in part, why resident males fight so hard to defend their territories.<ref name="Piperetal2008a">{{cite journal|author1=Piper, W.H.|author2=Walcott, C.|author3=Mager, J.N.|author4=Spilker, F.|name-list-style=amp|year=2008|title=Nestsite selection by male loons leads to sex-biased site familiarity|journal=Journal of Animal Ecology|volume=77|issue=2|pages=205–10|doi=10.1111/j.1365-2656.2007.01334.x|pmid=17976165|doi-access=free|bibcode=2008JAnEc..77..205P }}</ref>

Most [[Clutch (eggs)|clutches]] consist of two eggs, which are laid in May or June, depending upon latitude. Loon chicks are [[precocial]], able to swim and dive right away, but will often ride on their parents' back during their first two weeks to rest, conserve heat, and avoid predators. Chicks are fed mainly by their parents for about six weeks but gradually begin to feed themselves over time. By 11 or 12&nbsp;weeks, chicks gather almost all of their own food and have begun to fly.<ref name=Sjolander1972/><ref name=Sjolander1976/> In 2019, a necropsy of a [[bald eagle]] found floating on a Maine lake (beside the floating body of a loon chick) found that the eagle had been stabbed through the heart by an adult loon's beak.<ref>{{cite web |last=D'Auria |first=Danielle |date=2020-05-18 |title=Bald Eagle Shot Through the Heart – By a Loon! |url=https://www.maine.gov/ifw/blogs/mdifw-blog/bald-eagle-shot-through-heart-loon |access-date=2022-06-05 |website=Maine Department of Inland Fisheries & Wildlife}}</ref>

[[Biologist]]s, especially from [[Chapman University]], have extensively studied the mating behaviour of the [[common loon]] (''G. immer''). Contrary to popular belief, pairs seldom [[monogamy|mate for life]]. Indeed, a typical adult loon is likely to have several mates during its lifetime because of territorial takeover. Each breeding pair must frequently defend its territory against "floaters" (territory-less adults) trying to evict at least one owner and seize the breeding site. Territories that have produced chicks in the past year are especially prone to takeovers, because nonbreeding loons use chicks as cues to indicate high-quality territories. One-third of all territorial evictions among males result in the death of the owner; in contrast, female loons usually survive. Birds that are displaced from a territory but survive usually try to re-mate and (re)claim a breeding territory later in life.<ref name="Piperetal2008b">{{cite journal |author1=Piper, W.H. |author2=Walcott, C. |author3=Mager, J.N. |author4=Spilker, F. |name-list-style=amp |year=2008 |title=Fatal Battles in Common Loons: A Preliminary Analysis |journal=Animal Behaviour |volume=75 |issue=3 |pages=1109–15 |doi=10.1016/j.anbehav.2007.10.025 |s2cid=53178013}}</ref><ref name=Piperetal2000>{{cite book |last1=Piper |first1=W. H. |last2=Evers |first2=D. C. |last3=Meyer |first3=M. W. |last4=Tischler |first4=K. B. |last5=Klich |first5=M. |chapter=Do common loons mate for life?: scientific investigation of a widespread myth. |year=2000 |pages=43–49 |editor1-last=McIntyre |editor1-first=J. |editor2-last=Evers |editor2-first=D. C. |title=''Loons: Old History and New Findings.'' |publisher= |location= |isbn=}}</ref><ref>{{cite journal|author1=Piper, W.H.|author2=Tischler, K.B.|author3=Klich, M.|name-list-style=amp|year=2000|journal=Animal Behaviour|volume=59|issue=2|pages=385–94|doi=10.1006/anbe.1999.1295|title= Territory acquisition in loons: The importance of take-over|pmid=10675261|s2cid=23085958}}</ref><ref name=Piperetal2006>{{cite journal|author1=Piper, W.H.|author2=Walcott, C.|author3=Mager, J.N.|author4=Perala, M.|author5=Tischler, K.B.|author6=Harrington, Erin|author7=Turcotte, A.J.|author8=Schwabenlander M.|author9=Banfield, N.|name-list-style=amp|year=2006|title=Prospecting in a Solitary Breeder: Chick Production Elicits Territorial Intrusions in Common Loons|journal=Behavioral Ecology|volume=17|issue=6|pages= 881–888|doi=10.1093/beheco/arl021|doi-access=free}}</ref> 

In 2020, a loon hatched for the first time in over a century in Southeastern Massachusetts at Fall River, the Massachusetts Division of Fisheries and Wildlife and Biodiversity Research Institute. The chicks were relocated in 2015 with the hopes of re-establishing breeding and nesting patterns.<ref>{{Cite web|date=2020-07-10|title=Loon hatches for 1st time in century in southeastern region|url=https://apnews.com/bd5533ca130ecf9bcbca7afb3696c729|access-date=2020-07-10|website=AP NEWS}}</ref>