Pigeons don’t produce methane the way ruminants do AFAIK.
And, methane from livestock is only part of humanity’s climate altering activity.
http://www.ozarkbisons.com/aboutbison.php "Table : before 1800 60 million bisons in North America"
https://www.nass.usda.gov/Newsroom/2021/01-29-2021.php "There were 93.6 million head of cattle and calves on U.S. farms as of Jan. 1, 2021, according to the Cattle report published today by the U.S. Department of Agriculture’s National Agricultural Statistics Service (NASS)."
I didn't find number for ruminant megafauna in prehistoric times.
... > Humans account for about 36 percent of the biomass of all mammals. Domesticated livestock, mostly cows and pigs, account for 60 percent, and wild mammals for only 4 percent.
> The same holds true for birds. The biomass of poultry is about three times higher than that of wild birds.
> "It is definitely striking, our disproportionate place on Earth," Milo told The Guardian. "When I do a puzzle with my daughters, there is usually an elephant next to a giraffe next to a rhino. But if I was trying to give them a more realistic sense of the world, it would be a cow next to a cow next to a cow and then a chicken ... [0]
I would love to see how that compares to the great bison herds, or the great African savanna migrations
Maybe as an idea, just the food and the fact that bison etc used to have a more active life and varied foods than modern cows meant that they released less methane?
Lastly, ought be noted that methane releases from industrial agriculture are very much under counted and that might need to be accounted into the comparison [1]
[0] https://www-ecowatch-com.cdn.ampproject.org/v/s/www.ecowatch...
[1] https://www-technologynetworks-com.cdn.ampproject.org/v/s/ww...
Pre-Columbian animal density in the Americas was insane, from cod in the east, to buffalo in the middle, to salmon and sardines in the west. People thought it was limitless until it very abruptly wasn't.
I'm unsure about the fisheries, but the other numbers are debated now.
Until very recent times, the reports of European explorers pushing into the interior of North America were taken as a good proxy for the pre-Columbian state of those areas. We now know that those areas were far more densely populated before 1500 than they were more than 200 years later when European settlers started moving in. European diseases preceded European settlers and completely wiped out much of the continent's population.
AFIK, it's still being debated, but it seems reasonable that: - Predators like wolves kept large herd animal numbers relatively low - Large populations of Native Americans killed those predators but continued to keep the numbers of herd animals low via hunting - Native American population collapse coupled with low numbers of predator species allowed bison herd numbers to explode - European settlers arrived in the 1700s and 1800s and made the mistaken assumption that both the Native American and bison populations they encountered represented the way things had always been.
Feed lot cattle are another story.
Sorry, what?
There are claims it's all bullshit (ahem); I wouldn't automatically trust either side.
There are currently about 1.5 billion cattle worldwide, and each one weighs a lot more than 3 pigeons.
Worldwide livestock biomass significantly exceeds worldwide wild animal biomass: https://xkcd.com/1338/
The current livestock population can only be supported by industrialised agriculture.
Livestock biomass is also artificially increased both by many generations of selective breeding and by a known effect of certain hormones and antibiotics.
The actual methane emissions are a lot more complex than just count or biomass, as demonstrated even by the headline of the link (you wouldn’t see 55%, let alone 80%, if it wasn’t): https://journals.plos.org/plosone/article?id=10.1371/journal...
Finally, this planet does not actively manage global warming. It goes though glacial and interglacial periods precisely because of the absence of active management. The natural causes of this lead to the pre-industrial cycles, and are why the average temperature of this planet is so much higher than the average temperature of the moon: http://www.wolframalpha.com/input/?i=average%20temperature%2...
Venus had thermal runaway and the precipitation there is lead rather than water.
Martian winters cause ~25% of the atmosphere to condense into the polar (dry)ice caps.
There are some effects that cause unstable feedback loops though. Rising temperatures trigger several effects that lead to even more temperature rise. Reflective ice caps melt, tundra thaws releasing methane. Frozen methane in ocean sediments melts. Similarly our planet has been through several deep freeze events, far more severe than ice ages. If temperatures drop too much the ice reflects too much solar radiation leading to more freezing.
Humans are good at cultivating farting animals.
Do cows/cattle/livestock produce methane? Yes. So do humans.
How did the planet manage? For one, there was a helluva lot less other greenhouse warming gases in total larely due to human's industrial revolution. Once humans found out about using coal/oil/etc, it quickly dwarfed anything ever seen other than volanic eruptions.
The livestock methane argument has always sounded like a BigOil tactic rather than a scientific one to deflect blame, and then championed by someone like PETA to help further their agenda. How significant would livestock methane emmisions be to the climate if ICE pollution was elminitated?