Editing Passenger pigeon (section)

===Extinction causes===
[[File:Martha, the last Passenger Pigeon. Natural History Museum, June, 2015. Digital photo, cropped and brightened.jpg|upright|thumb|left|Martha at the [[Smithsonian Museum]], 2015]]

The main reasons for the extinction of the passenger pigeon were the massive scale of hunting, the rapid loss of habitat, and the extremely social lifestyle of the bird, which made it highly vulnerable to the former factors. [[Deforestation]] was driven by the need to free land for agriculture and expanding towns, but also due to the demand for lumber and fuel. About 728,000&nbsp;km<sup>2</sup> (180 million acres) were cleared for farming between 1850 and 1910. Though there are still large woodland areas in eastern North America, which support a variety of wildlife, it was not enough to support the vast number of passenger pigeons needed to sustain the population. In contrast, very small populations of nearly extinct birds, such as the [[kākāpō]] (''Strigops habroptilus'') and the [[takahē]] (''Porphyrio hochstetteri''), have been enough to keep those species extant to the present. The combined effects of intense hunting and deforestation has been referred to as a "[[Blitzkrieg]]" against the passenger pigeon, and it has been labeled one of the greatest and most senseless human-induced extinctions in history.<ref name="Fuller 2014 72–88"/><ref name="Hung 2014"/><ref name="Hume 2015"/> As the flocks dwindled in size, the passenger pigeon population decreased below the threshold necessary to propagate the species,<ref>{{cite journal |last1=Halliday |first1=T. |title=The extinction of the passenger pigeon ''Ectopistes migratorius'' and its relevance to contemporary conservation |journal=[[Biological Conservation (journal) |Biological Conservation]] |volume=17 |issue=2 |pages=157–162 |year=1980 |bibcode=1980BCons..17..157H |doi=10.1016/0006-3207(80)90046-4}}</ref> an example of the [[Allee effect]].<ref>{{cite web |title=Passenger Pigeon/Allee effect |website=kevintshoemaker.github.io |url=https://kevintshoemaker.github.io/NRES-470/LECTURE5.html |access-date=2020-09-25}}</ref>

[[File:Passenger pigeon shooting in Iowa.jpg|thumb|Pigeons being shot to save crops in Iowa, 1867]]
The 2014 genetic study that found natural fluctuations in population numbers prior to human arrival also concluded that the species routinely recovered from lows in the population, and suggested that one of these lows may have coincided with the intensified hunting by humans in the 1800s, a combination which would have led to the rapid extinction of the species. A similar scenario may also explain the rapid extinction of the [[Rocky Mountain locust]] (''Melanoplus spretus'') during the same period.<ref name="Hung 2014"/> It has also been suggested that after the population was thinned out, it would be harder for few or solitary birds to locate suitable feeding areas.<ref name="Extinct Birds"/> In addition to the birds killed or driven away by hunting during breeding seasons, many nestlings were also orphaned before being able to fend for themselves. Other, less convincing contributing factors have been suggested at times, including mass drownings, [[Newcastle disease]], and migrations to areas outside their original range.<ref name="iucn status 19 November 2021"/><ref name="Fuller 2014 72–88"/>

The extinction of the passenger pigeon aroused public interest in the [[conservation movement]], and resulted in new laws and practices which prevented many other species from becoming extinct.<ref name="SI"/> The rapid decline of the passenger pigeon has influenced later assessment methods of the extinction risk of endangered animal populations. The [[International Union for Conservation of Nature]] (IUCN) has used the passenger pigeon as an example in cases where a species was declared "at risk" for extinction even though population numbers are high.<ref name=ext/>

Naturalist [[Aldo Leopold]] paid tribute to the vanished species in a monument dedication held by the Wisconsin Society for Ornithology at [[Wyalusing State Park]], [[Wisconsin]], which had been one of the species' social roost sites.<ref>{{cite web |title=Passenger Pigeon Monument |date=December 2003 |publisher=Wisconsin Historical Society |url=https://www.wisconsinhistory.org/Records/Image/IM34684 |access-date=October 8, 2024}}</ref> Speaking on May 11, 1947, Leopold remarked:
{{Blockquote|Men still live who, in their youth, remember pigeons. Trees still live who, in their youth, were shaken by a living wind. But a decade hence only the oldest oaks will remember, and at long last only the hills will know.<ref name="Leopold">{{cite book |title=[[A Sand County Almanac]]: And Sketches Here and There |last=Leopold |first=Aldo |orig-year=1949 |year=1989 |publisher=[[Oxford University Press]] |location=[[New York City |New York]] |isbn=0-19-505928-X |page=109}}</ref>}}