Editing Common loon (section)

==== Breeding range decline ====
The common loon's breeding range has moved northward, the species breeding as far south as Iowa a century ago.<ref name=":5">{{Cite web|url=http://seagrant.wisc.edu/birds/Common_Loon_conservation.html|title=Common Loon Conservation Status- Migratory Birds of the Great Lakes – University of Wisconsin Sea Grant Institute|last=Wiland|first=L.|date=2007 |archive-url=https://web.archive.org/web/20170712112025/http://seagrant.wisc.edu/birds/Common_Loon_conservation.html|archive-date=12 July 2017|access-date=12 July 2017}}</ref> It too is adversely affected by [[acid rain]] and pollution, as well as lead poisoning from fishing sinkers (especially those that are about the size of the grit stones they ingest<ref>{{Cite journal | last1=Franson | first1=J. Christian | last2=Hansen | first2=Scott P. | last3=Pokras | first3=Mark A. | last4=Miconi | first4=Rose | date=2001 | title=Size characteristics of stones ingested by common loons | jstor=1369696 | journal=The Condor | volume=103 | issue=1 | pages=189–191 | doi=10.1650/0010-5422(2001)103[0189:scosib]2.0.co;2| s2cid=86704804 | doi-access=free }}</ref>) and mercury contamination from industrial waste.<ref name="locke">{{cite journal | last1=Locke | first1=L.N. | last2=Kerr | first2=S.M.| last3=Zoromski | first3=D. | title=Lead poisoning in common loons (''Gavia immer'') | journal=Avian Diseases | volume=26| issue=2 | pages=392–396 | year=1982 | doi= 10.2307/1590110 | jstor=1590110 | pmid=7103895 | citeseerx=10.1.1.514.3406 }}</ref> Heavy metals such as mercury may be partially removed through biological processes such as excretion or deposition in feathers, but their adverse effects are [[biomagnification|magnified]] through concentration of the toxic elements in organs such as the liver. Eggs shells may also contain metal contaminants,<ref name="burger">{{cite journal | last1=Burger | first1=Joanna | last2=Pokras | first2=Mark | last3=Chafel | first3=Rebecca | last4=Gochfeld | first4=Michael | title=Heavy metal concentrations in feathers of common loons (''Gavia immer'') in the northeastern United States and age differences in mercury levels | journal=Environmental Monitoring and Assessment | volume=30 | issue=1| pages=1–7 | year =1994 | doi=10.1007/BF00546196 | pmid=24213705 | bibcode=1994EMnAs..30....1B | s2cid=24178181 }}</ref> leading to low reproductive productivity. High levels of heavy metals are linked to loons being in poor condition,<ref name="Scheuhammer">{{cite journal | last1=Scheuhammer | first1=Anton M. | last2=Wong | first2=Allan H.K. | last3=Bond | first3=Della | title=Mercury and selenium accumulation in common loons (''Gavia immer'') and common mergansers (''Mergus merganser'') from Eastern Canada | journal=Environmental Toxicology and Chemistry | volume=17 | issue=2 | pages=197–201| year=1998 | doi=10.1002/etc.5620170209 | s2cid=85336567 }}</ref> males being affected more because they eat larger fish.<ref name="MNFI" />

The common loon has also faced a decline in breeding range due to hunting, predation, and water-level fluctuations, or flooding. Some environmentalists attempt to increase nesting success by mitigating the effects of some of these threats, namely terrestrial predation and water-level fluctuations, through the deployment of rafts in the loon's breeding territories.<ref>{{Cite journal|last1=Desorbo|first1=Christopher R|last2=Taylor|first2=Kate M.|last3=Kramar|first3=David E. | last4=Fair | first4=Jeff | last5=Cooley | first5=John H. | last6=Evers | first6=David C. | last7=Hanson | first7=William | last8=Vogel | first8=Harry S. | last9=Atwood | first9=Jonathan L. |date=2007 | title=Reproductive advantages for common loons using rafts | journal=Journal of Wildlife Management | volume=71 | issue=4 | pages=1206–1213 | doi=10.2193/2006-422|bibcode=2007JWMan..71.1206D |s2cid=85992979|issn=0022-541X }}</ref> In addition, artificial floating nesting platforms have been provided for the common loon in some lakes to reduce the impact of changing water levels due to dams and other human activities.<ref>{{Cite journal|last1=McIntyre|first1=Judith W. | last2=Mathisen | first2=John E. | date=1977 | title=Artificial islands as nest sites for common loons | journal=The Journal of Wildlife Management | volume=41 | issue=2 | pages=317–319 | doi=10.2307/3800613 | jstor=3800613 }}</ref> The common loon abandons lakes that fail to provide suitable nesting habitat due to shoreline development. It is endangered by personal water-craft and powerboats that may drown newly born chicks, wash eggs away, or swamp nests.<ref name=":5" /> It is still considered an "injured" species in Alaska as a result of the [[Exxon Valdez oil spill]].<ref name=":4" />