Almost all of the world’s mammal biomass is humans and livestock
A diverse range of mammals once roamed the planet.
地球上曾经生活过各种各样的哺乳动物。
This changed dramatically with the arrival of humans, who have become the dominant species through our own populations, as well as the animals we breed and raise for food.
随着人类的到来，这种情况发生了巨大的变化，人类已经通过我们自己的种群以及我们饲养和饲养的食物成为优势物种。
There are various ways to compare the distribution or abundance of different types of mammals.
有多种方法可以比较不同类型哺乳动物的分布或丰度。
One way is to compare them based on the number of individuals.
一种方法是根据个体数量进行比较。
In these terms, very small animals vastly outnumber larger animals, but this doesn’t necessarily give us an idea of how much ecological and biological resources different animals use.
从这些角度来看，非常小的动物的数量远远多于大型动物，但这并不一定能让我们了解不同动物使用了多少生态和生物资源。
Another metric that ecologists often use is biomass — the total weight of all animals of a given species.
生态学家经常使用的另一个指标是生物量——特定物种的所有动物的总重量。
This not only takes into account the number of animals but also factors in their size.
这不仅考虑到动物的数量，还考虑到它们的体型。
1 It gives more weight to larger animals at higher levels of the ecological “pyramid”: these rely on well-functioning bases below them.
1 它赋予生态“金字塔”较高层的大型动物更多的权重：这些动物依赖于其下方运转良好的基础。
Let’s then look at the breakdown of the global mammal kingdom in these terms.
然后让我们从这些方面来看看全球哺乳动物王国的崩溃。
2 It’s shown in the chart below.
2 如下图所示。
This data is sourced from the study by Lior Greenspoon and colleagues.
该数据来自 Lior Greenspoon 及其同事的研究。
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Each square represents one percent of the world’s mammal biomass, including both land and marine animals.
每个方块代表世界哺乳动物生物量的百分之一，包括陆地和海洋动物。
For context, that 1% is equal to around 11 million tonnes.
就上下文而言，这 1% 相当于约 1100 万吨。
The dominance of humans is clear.
人类的统治地位是显而易见的。
We account for more than one-third of mammal biomass.
我们占哺乳动物生物量的三分之一以上。
Our biomass is more than seven times greater than all wild mammals combined.
我们的生物量是所有野生哺乳动物总和的七倍多。
Our livestock and pets, which are primarily cattle, account for 59%.
我们的牲畜和宠物以牛为主，占59%。
That leaves just 5% as wild mammals, which includes thousands of different species, from elephants and deer to lions and whales.
这样一来，野生哺乳动物就只剩下 5%，其中包括数千种不同的物种，从大象、鹿到狮子和鲸鱼。
Beyond the totals for humans, livestock, and wild animals, there are a few striking comparisons that we found surprising.
除了人类、牲畜和野生动物的总数之外，还有一些令人惊讶的惊人比较。
Farmed pigs weigh as much as all of the world’s whales, orcas, sea otters, seals, and dolphins combined.
养殖猪的重量相当于世界上所有鲸鱼、逆戟鲸、海獭、海豹和海豚的总和。
All the dogs in the world, including pets and feral dogs, weigh as much as all wild mammals on land.
世界上所有的狗，包括宠物和野狗，其重量与陆地上所有野生哺乳动物一样重。
When we show people the chart above, one question often comes up: what about chickens?
当我们向人们展示上面的图表时，经常会出现一个问题：鸡呢？
Of course, chickens are not mammals.
当然，鸡不是哺乳动物。
But we can make a similar comparison between poultry and wild birds.
但我们可以对家禽和野鸟进行类似的比较。
Like mammals, poultry livestock collectively weigh much more than all the world’s wild birds.
与哺乳动物一样，家禽牲畜的总重量比世界上所有野生鸟类都要重得多。
You can see this in the next chart.
您可以在下一张图表中看到这一点。
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The size of the difference between poultry and wild birds, though, is much less certain than it is for humans and livestock versus wild mammals.
然而，家禽和野生鸟类之间的差异大小，远不如人类和牲畜与野生哺乳动物之间的差异大小那么确定。
That’s because estimates for the number of wild birds vary a lot.
这是因为对野生鸟类数量的估计差异很大。
The underlying study that this data comes from uses several methods to estimate the weight of wild birds globally.
该数据来源的基础研究使用多种方法来估计全球野生鸟类的重量。
The different techniques yield quite different estimates: 5 million tonnes in one, and 24 million tonnes in the other.
不同的技术得出的估计结果截然不同：一种为 500 万吨，另一种为 2400 万吨。
They take the geometric mean of the two, which is their final estimate shown below.
他们取两者的几何平均值，这是他们的最终估计，如下所示。
It suggests that poultry weigh more than twice as much as wild birds.
这表明家禽的重量是野生鸟类的两倍多。
But this result is clearly very sensitive to the choice of methodology.
但这个结果显然对方法论的选择非常敏感。
If we used the “5 million tonnes” figure, then wild birds would account for just 14%.
如果用“500万吨”这个数字，那么野生鸟类只占14%。
If we assumed 24 million tonnes, they’d be 44%.
如果我们假设 2400 万吨，则为 44%。
We explain this uncertainty in more detail in our appendix at the end of this article.
我们在本文末尾的附录中更详细地解释了这种不确定性。
Using any method, the overall direction of the result is the same: chickens and other livestock birds weigh more than their wild cousins.
使用任何方法，结果的总体方向都是相同的：鸡和其他家畜鸟类比它们的野生近亲重。
We send two regular newsletters so you can stay up to date on our work and receive curated highlights from across Our World in Data.
我们定期发送两份时事通讯，以便您及时了解我们的工作并接收来自“我们的数据世界”的精选亮点。
A huge decline in the number and size of wild mammals has played a major role.
野生哺乳动物数量和体型的大幅下降起到了重要作用。
Estimates suggest that the biomass of wild mammals has declined by roughly 85% over the last 100,000 years, and particularly since the migration of human populations across the planet.
据估计，野生哺乳动物的生物量在过去 10 万年中下降了约 85%，特别是自从人类在全球范围内迁徙以来。
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But that’s not the only reason.
但这不是唯一的原因。
It’s not that the abundance of wild mammals was replaced one by one by humans and livestock.
这并不是说大量的野生哺乳动物被人类和牲畜一一取代。
In fact, human activity has dramatically increased the total amount of mammal biomass on the planet.
事实上，人类活动极大地增加了地球上哺乳动物生物量的总量。
Around 100,000 years ago, the total biomass of land mammals summed up to approximately 120 million tonnes, essentially all of it in the form of wild animals.
大约10万年前，陆地哺乳动物的总生物量总计约1.2亿吨，基本上全部以野生动物的形式存在。
6 By 10,000 years ago, this had fallen to 90 million tonnes.
6 到 10,000 年前，这一数字已降至 9,000 万吨。
But the most dramatic changes followed the advent of agriculture.
但最戏剧性的变化是随着农业的出现而发生的。
Wild mammal populations and biomass continued to decline, while human and livestock populations gradually increased.
野生哺乳动物数量和生物量持续下降，而人类和牲畜数量逐渐增加。
By 1850, the total mammal biomass on land — including wild animals, humans, and livestock — had increased to an estimated 250 million tonnes.
到 1850 年，陆地上哺乳动物的总生物量（包括野生动物、人类和牲畜）估计已增加到 2.5 亿吨。
7 Since then, this has continued to increase rapidly.
7 此后，这一数字继续快速增长。
Today, mammals weigh roughly 1100 million tonnes, which represents a quadrupling since 1850.
如今，哺乳动物的重量约为 11 亿吨，自 1850 年以来增加了四倍。
Wild mammals declined, but this was more than offset by the huge rise in biomass of humans and farmed mammals.
野生哺乳动物数量减少，但这被人类和养殖哺乳动物生物量的大幅增加所抵消。
Humans achieved this by harnessing external resources and energy inputs that weren’t available to wild animal populations before.
人类通过利用野生动物种群以前无法获得的外部资源和能源输入来实现这一目标。
We’ve used fossil fuels and agricultural innovations to harness synthetic fertilizers.
我们利用化石燃料和农业创新来利用合成肥料。
We’ve engineered extremely productive crop varieties that grow much faster — and supply more energy — than conventional plants.
我们培育出了产量极高的作物品种，它们比传统植物生长得更快，并提供更多的能量。
We’ve cleared land to make space for raising livestock at higher densities than you’d find them in the wild.
我们清理了土地，腾出空间来饲养牲畜，其密度高于野外。
Essentially, we’ve added huge amounts of energy to the system that was there in the absence of human populations.
从本质上讲，我们已经为没有人类存在的系统添加了大量的能量。
But while the mammal kingdom is more “vast” than ever before, this has, at least so far, come at the cost of diversity.
尽管哺乳动物王国比以往任何时候都更加“庞大”，但这至少到目前为止是以多样性为代价的。
Wild mammals have shrunk not just in relative terms, but also in absolute terms.
野生哺乳动物的数量不仅在相对数量上有所减少，而且在绝对数量上也有所减少。
Thanks to Marwa Boukarim for her help on design and visualization, and to Max Roser and Edouard Mathieu for feedback and comments on this article.
感谢 Marwa Boukarim 在设计和可视化方面的帮助，并感谢 Max Roser 和 Edouard Mathieu 对本文的反馈和评论。
A small number of species dominate the distribution of wild mammal biomass.
少数物种主导野生哺乳动物生物量的分布。
Humans hunted many of the world’s large mammals to extinction.
人类猎杀世界上许多大型哺乳动物直至灭绝。
This threat still exists today, but it doesn’t have to be that way.
这种威胁今天仍然存在，但不一定是这样。
Wild mammal biomass has declined by 85% since the rise of humans.
自人类崛起以来，野生哺乳动物的生物量已下降 85%。
But we can turn things around by reducing the amount of land we use for agriculture.
但我们可以通过减少农业用地来扭转局面。
In the sections below, we detail the methods and figures that the authors of the scientific papers used in producing the statistics shown in this article.
在下面的部分中，我们详细介绍了科学论文作者在生成本文所示统计数据时使用的方法和数据。
We do this to help make the work and methodology more transparent and understandable.
我们这样做是为了帮助使工作和方法更加透明和易于理解。
Unless otherwise stated, the methods we’re describing are those of the paper by Lior Greenspoon et al.
除非另有说明，我们描述的方法是 Lior Greenspoon 等人论文中的方法。
(2023).
（2023）。
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To calculate the biomass of humans, the authors take global population figures for 2021 from the UN Population Division’s World Population Prospects and multiply this by an age-weighted average body mass of 50 kilograms per person.
为了计算人类生物量，作者从联合国人口司的《世界人口展望》中获取了 2021 年全球人口数据，并将其乘以每人 50 公斤的年龄加权平均体重。
This is relatively small for an adult, but when averaged across children and adults, it seems like a reasonable estimate.
对于成年人来说，这个数字相对较小，但是当对儿童和成人进行平均时，这似乎是一个合理的估计。
In 2021, the global population was around 7.95 billion.
2021年，全球人口约为79.5亿。
Multiplying by 50 kilograms gives a total weight of 398 million tonnes.
乘以 50 公斤得出总重量为 3.98 亿吨。
To calculate the biomass of farm livestock, the authors take livestock population figures for 2018 from the Food and Agriculture Organization of the United Nations.
为了计算农场牲畜的生物量，作者从联合国粮食及农业组织获取了 2018 年牲畜数量数据。
The data for all animals, excluding cattle and pigs, is available here .
所有动物（不包括牛和猪）的数据可在此处获取。
The data for cattle and pigs is here .
牛和猪的数据在这里。
To get the total mass of these animals, they multiply each type by their average respective weight in different world regions.
为了得到这些动物的总质量，他们将每种动物乘以它们在世界不同地区的平均体重。
These weights come from this inventory guideline report from the Intergovernmental Panel on Climate Change (IPCC), and are listed here .
这些权重来自政府间气候变化专门委员会 (IPCC) 的清单指南报告，并列于此处。
The authors produce biomass estimates for four types of pets: dogs, cats, rats, and mice.
作者对四种宠物的生物量进行了估计：狗、猫、大鼠和小鼠。
You can find their table of assumptions and estimates here .
您可以在此处找到他们的假设和估计表。
For dogs , the global population is estimated to be 987 million.
对于狗来说，全球数量估计为 9.87 亿。
This comes from the chapter “The dog-human-wildlife interface: assessing the scope of the problem” in the book Free-Ranging Dogs and Wildlife Conservation .
这来自《自由放养的狗和野生动物保护》一书中的“狗-人类-野生动物界面：评估问题的范围”一章。
This includes domesticated and feral dogs (which is where a lot of the uncertainty comes from).
这包括家养狗和野狗（这是很多不确定性的来源）。
For example, around one-quarter of the global total comes from rural China, where there is approximately one dog for every 2.9 humans.
例如，全球总数的约四分之一来自中国农村，那里大约每 2.9 个人就有一只狗。
We were initially skeptical about these figures and found it difficult to trace the exact source for each estimate.
我们最初对这些数字持怀疑态度，并发现很难追踪每个估计的确切来源。
However, upon further examination of the literature, commonly cited figures range from approximately 700 to 900 million.
然而，根据对文献的进一步审查，普遍引用的数字约为 700 至 9 亿。
We therefore cautiously concluded that a population estimate of 1 billion does not seem unreasonable, although it’s on the higher end.
因此，我们谨慎地得出结论，人口估计为 10 亿似乎并非不合理，尽管这个数字偏高。
To get a total weight, they assume an average weight of 22 kilograms per dog.
为了获得总重量，他们假设每只狗的平均重量为 22 公斤。
9 For context, this is roughly the weight of an average Border Collie, Australian Shepherd, or English Springer Spaniel.
9 就上下文而言，这大约是边境牧羊犬、澳大利亚牧羊犬或英国史宾格犬的平均体重。
In the original study, Greenspoon et al.
在最初的研究中，Greenspoon 等人。
(2023) give a final estimate of 20 million tonnes.
（2023）给出的最终估计为 2000 万吨。
We find it plausible that it falls within the range of 15 to 20 million tonnes, so their estimate is on the higher end.
我们认为这个数字似乎在 15 至 2000 万吨范围内，因此他们的估计偏高。
For cats , they assume a global population of 600 million, and an average mass of 3.75 kilograms.
对于猫来说，假设全球有 6 亿只猫，平均体重为 3.75 公斤。
10 Based on personal experience, this seems like a fair estimate for the average cat.
10 根据个人经验，这似乎是对普通猫的合理估计。
The total biomass of cats — at 2.3 million tonnes — is not large enough to feature in the main graphic in this article.
猫的总生物量为 230 万吨，不足以出现在本文的主图中。
The same is true for rats and mice, which collectively weigh an order of magnitude less.
对于大鼠和小鼠来说也是如此，它们的总重量要轻一个数量级。
The estimates of wild mammal biomass have the largest uncertainty.
野生哺乳动物生物量的估计具有最大的不确定性。
In a separate article, we look at the distribution of wild mammals specifically, using the estimates from this paper.
在另一篇文章中，我们使用本文的估计值专门研究了野生哺乳动物的分布。
There, we provide more detail on population estimates and their methodologies.
在那里，我们提供了有关人口估计及其方法的更多详细信息。
But briefly, the authors use global population reports — which give estimates of the total number of animals — for roughly 6% of land mammal species.
但简单来说，作者使用了全球人口报告——其中估计了大约 6% 的陆地哺乳动物物种的动物总数。
They then use the average weights of these animals to calculate their biomass.
然后他们使用这些动物的平均体重来计算它们的生物量。
The biomass of the remaining wild land mammal species was estimated using a Support Vector Regression model.
使用支持向量回归模型估计剩余野生陆地哺乳动物物种的生物量。
It might seem odd to base total estimates based on records for just 6% of species, but this small fraction dominates total mammal biomass; the remaining 94% make up a relatively small fraction.
仅根据 6% 物种的记录来进行总估计似乎很奇怪，但这一小部分在哺乳动物总生物量中占主导地位；剩下的 94% 所占比例相对较小。
This does introduce significant uncertainty; however, the overall conclusions of this article and the visualization would not change under different assumptions.
这确实带来了很大的不确定性；然而，本文的整体结论和可视化在不同的假设下不会改变。
Wild mammals’ share of total biomass might change by as much as a few percentage points in either direction, but the fact that they make up far less than 10% remains true.
野生哺乳动物在总生物量中所占的份额可能会朝任一方向变化多达几个百分点，但它们所占比例远低于 10% 的事实仍然是事实。
Unlike the mammal figures, the data for poultry and wild birds comes from the earlier article by Bar-On et al.
与哺乳动物的数据不同，家禽和野鸟的数据来自 Bar-On 等人之前的文章。
(2018).
（2018）。
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They calculated the biomass of wild birds using two slightly different sources and methodologies.
他们使用两种略有不同的来源和方法计算了野生鸟类的生物量。
In the first, they used wild bird population figures from a 1997 paper by Gaston and Blackburn, who extrapolated bird densities (the number of birds per unit area) across different environments and regions to derive a global total.
首先，他们使用了加斯顿和布莱克本 1997 年论文中的野生鸟类数量数据，他们推断了不同环境和地区的鸟类密度（每单位面积的鸟类数量），得出了全球总数。
11 Using slightly different models and extrapolations gave a similar figure of around 200 to 400 billion wild birds globally.
11 使用略有不同的模型和外推法得出了类似的数字，全球约有 200 至 4000 亿只野生鸟类。
To calculate the combined weight of these birds, they used data on the relationship between bird population density and body weight among British birds.
为了计算这些鸟类的总重量，他们使用了英国鸟类种群密度与体重之间关系的数据。
12 Based on this, they arrived at a weighted average of around 80 grams per bird.
12 据此，他们得出每只鸡的加权平均重量约为 80 克。
If we multiply this by 300 billion (the mid-point population estimate), we get a weight of 24 million tonnes.
如果我们将其乘以 3000 亿（人口估计中值），我们就会得到 2400 万吨的重量。
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They also applied another methodology, using the individual mass and population densities of around 900 bird species, then extrapolating that out to all known bird species.
他们还应用了另一种方法，使用约 900 种鸟类的个体质量和种群密度，然后将其推断到所有已知的鸟类。
This gave a result of 5 million tonnes.
结果是 500 万吨。
In their paper, they took the geometric mean of the two estimates (24 million and 5 million) to get a final estimate of 11 million tonnes.
在他们的论文中，他们采用了两个估计值（2400 万吨和 500 万吨）的几何平均值，得到了 1100 万吨的最终估计值。
The fact that the two methodologies yielded pretty different results — the first being more than four times higher — highlights the level of uncertainty in these wild population estimates.
事实上，这两种方法产生了截然不同的结果——第一种方法高出四倍多——凸显了这些野生种群估计的不确定性程度。
Just to make this even clearer: a more recent paper produced a much lower estimate of wild bird abundance of just 50 billion.
为了更清楚地说明这一点：最近的一篇论文对野生鸟类丰度的估计要低得多，仅为 500 亿只。
14 However, the uncertainty was huge, ranging from 3.9 billion to 2.1 trillion, resulting in a strong response from other researchers.
14 然而，不确定性巨大，从 39 亿到 2.1 万亿不等，引起了其他研究人员的强烈反应。
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They calculated the weight of poultry in a similar way to other livestock species (see the section above on “Livestock”).
他们以与其他牲畜物种类似的方式计算家禽的重量（参见上面“牲畜”部分）。
They took population figures from the Food and Agriculture Organization of the United Nations and multiplied them by their respective weights, detailed in this inventory guideline report from the Intergovernmental Panel on Climate Change (IPCC).
他们采用了联合国粮食及农业组织的人口数据，并将其乘以各自的权重，政府间气候变化专门委员会 (IPCC) 的清单指南报告对此进行了详细说明。
This gave a result of around 30 million tonnes.
结果约为 3000 万吨。
The final result is, then, very sensitive to the assumptions made in these comparisons.
因此，最终结果对这些比较中所做的假设非常敏感。
Using any of the estimates, poultry outweigh wild birds.
无论使用哪种估计，家禽的重量都超过了野生鸟类。
However, using the 24 million tonnes for wild birds from the first methodology means the gap is relatively close.
然而，使用第一种方法中的 2400 万吨野生鸟类意味着差距相对较小。
Using the 5 million tonnes figure would mean that wild birds were just 14% of total bird biomass.
使用 500 万吨这一数字意味着野生鸟类仅占鸟类总生物量的 14%。
To calculate the biomass of a taxonomic group, the researchers multiplied the average weight of a given animal by the number of individuals in that group.
为了计算分类群体的生物量，研究人员将给定动物的平均体重乘以该群体中的个体数量。
In humans, for example, they take the average weight of a person and multiply it by the human population.
例如，对于人类，他们将一个人的平均体重乘以人口总数。
Sometimes this is given in tonnes of carbon .
有时以碳吨为单位。
To estimate that, you can take the “wet biomass” — the total of an animal when it’s alive — and divide by six.
为了估计这一点，您可以将“湿生物量”（动物活着时的总量）除以六。
Unfortunately, due to data availability, not all of these estimates are for the same year.
不幸的是，由于数据的可用性，并非所有这些估计都针对同一年。
2018 is the year used to calculate the weight of livestock.
2018年是计算牲畜重量的一年。
For humans, the year was 2021.
对于人类来说，这一年是2021年。
For wild mammals, there is even greater variability.
对于野生哺乳动物来说，变异性更大。
These differences are worth noting, but are likely to have only marginal impacts on the final figures.
这些差异值得注意，但可能只会对最终数据产生边际影响。
Greenspoon, L., Krieger, E., Sender, R., Rosenberg, Y., Bar-On, Y.
Greenspoon, L.、Krieger, E.、Sender, R.、Rosenberg, Y.、Bar-On, Y.
M., Moran, U., ...
M.，莫兰，U.，...
& Milo, R.
& 米洛，R.
(2023).
（2023）。
The global biomass of wild mammals.
野生哺乳动物的全球生物量。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
In an earlier version of this article, we presented data from an earlier paper from Bar-On et al.
在本文的早期版本中，我们提供了 Bar-On 等人早期论文中的数据。
(2018).
（2018）。
The results are similar, but the Greenspoon et al.
结果相似，但 Greenspoon 等人。
(2023) paper gives updated estimates.
(2023) 论文给出了更新的估计。
Bar-On, Y.
巴昂，Y.
M., Phillips, R., & Milo, R.
M.、菲利普斯，R. 和米洛，R.
(2018).
（2018）。
The biomass distribution on Earth.
地球上的生物量分布。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
For the bird comparison, we’ve used data from the study by Bar-On et al.
为了进行鸟类比较，我们使用了 Bar-On 等人的研究数据。
(2018).
（2018）。
Bar-On, Y.
巴昂，Y.
M., Phillips, R., & Milo, R.
M.、菲利普斯，R. 和米洛，R.
(2018).
（2018）。
The biomass distribution on Earth.
地球上的生物量分布。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
Bar-On, Y.
巴昂，Y.
M., Phillips, R., & Milo, R.
M.、菲利普斯，R. 和米洛，R.
(2018).
（2018）。
The biomass distribution on Earth.
地球上的生物量分布。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
Barnosky, A.
巴诺斯基，A.
D.
D .
(2008).
（2008）。
Megafauna biomass tradeoff as a driver of Quaternary and future extinctions.
巨型动物生物量权衡是第四纪和未来灭绝的驱动因素。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
This figure comes from Greenspoon et al.
这个数字来自 Greenspoon 等人。
(2025).
（2025）。
The global biomass of mammals since 1850.
1850 年以来全球哺乳动物生物量。
Nature Communications.
自然通讯。
The authors attempt to quantify the change in global mammal biomass since 1850.
作者试图量化 1850 年以来全球哺乳动物生物量的变化。
These figures, especially for wild mammals, are highly uncertain, especially further back in time.
这些数字，尤其是野生哺乳动物的数字，是高度不确定的，尤其是在更早的时间里。
They estimate that humans and livestock weighed 200 million tonnes, and wild land mammals, 50 million tonnes.
他们估计人类和牲畜的重量为 2 亿吨，野生陆地哺乳动物的重量为 5000 万吨。
The 200 million figure is likely to be much more certain than the latter.
2亿这个数字很可能比后者更加确定。
Greenspoon, L., Krieger, E., Sender, R., Rosenberg, Y., Bar-On, Y.
Greenspoon, L.、Krieger, E.、Sender, R.、Rosenberg, Y.、Bar-On, Y.
M., Moran, U., ...
M.，莫兰，U.，...
& Milo, R.
& 米洛，R.
(2023).
（2023）。
The global biomass of wild mammals.
野生哺乳动物的全球生物量。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
P.
P。
F.
F。
Woodall, I.
伍德尔，I.
P.
P。
Johnstone, Dimensions and allometry of testes, epididymides and spermatozoa in the domestic dog (Canis familiaris).
约翰斯通，家养狗（Canisamilis）睾丸、附睾和精子的尺寸和异速生长。
Journal of Reproduction and Fertility.
生殖与生育杂志。
Young et al.
杨等人。
(2011), Urban carnivores: Ecology, conflict, conservation.
(2011)，城市食肉动物：生态、冲突、保护。
The Journal of Wildlife Management.
野生动物管理杂志。
Gaston KJ, Blackburn TM (1997).
加斯顿 KJ，布莱克本 TM (1997)。
How many birds are there?
有多少只鸟？
Biodiversity Conservation.
生物多样性保护。
Nee, S., Read, A.
Nee，S.，里德，A.
F., Greenwood, J.
F.，格林伍德，J.
J., & Harvey, P.
J.，&哈维，P.
H.
H.
(1991).
（1991）。
The relationship between abundance and body size in British birds.
英国鸟类的丰度与体型之间的关系。
Nature.
自然。
In the original paper, the authors calculate this weight in tonnes of carbon.
在最初的论文中，作者计算了这个重量（以吨碳为单位）。
To convert our wet weight to tonnes of carbon, you’d divide by 6.
要将我们的湿重换算成碳吨数，您需要除以 6。
That would give 4 million tonnes of carbon.
这将产生 400 万吨碳。
Callaghan, C.
卡拉汉，C.
T., Nakagawa, S., & Cornwell, W.
T.、中川 S. 和康威尔 W.
K.
K.
(2021).
（2021）。
Global abundance estimates for 9,700 bird species.
全球 9,700 种鸟类的丰度估计。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
Robinson, O.
罗宾逊，O.
J., Socolar, J.
J.，索科拉尔，J.
B., Stuber, E.
B.、斯图伯、E.
F., Auer, T., Berryman, A.
F.、奥尔，T.、贝里曼，A.
J., Boersch-Supan, P.
J.、Boersch-Supan、P.
H., ...
H.，...
& Johnston, A.
＆约翰斯顿，A.
(2022).
（2022）。
Extreme uncertainty and unquantifiable bias do not inform population sizes.
极端的不确定性和无法量化的偏差并不能说明人口规模。
Proceedings of the National Academy of Sciences.
美国国家科学院院刊。
Our articles and data visualizations rely on work from many different people and organizations.
我们的文章和数据可视化依赖于许多不同的人和组织的工作。
When citing this article, please also cite the underlying data sources.
引用本文时，请同时注明底层数据来源。
This article can be cited as:
这篇文章可以引用为：
We are a live site and we keep our work maintained.
我们是一个活跃的网站，我们会保持我们的工作。
So our articles are often changed, including the data.
所以我们的文章经常改，包括数据。
You can browse previous versions of this work here.
您可以在此处浏览此作品的先前版本。