<p>Kelliher, F. M., &amp; Clark, H. (2010). Methane emissions from bison-An historic herd estimate for the North American Great Plains. Agricultural and Forest Meteorology, 150(3), 473-477.</p>
<p>Abstract<br />Enteric methane (CH4) emissions were estimated from 30&nbsp;M bison (Bison bison) across the North American Great Plains before contact with European settlers. We compiled the first historic emissions inventory using an Intergovernmental Panel on Climate Change (IPCC) Tier 2 method. The emissions were governed by the energy requirements for grazing, growth and reproduction. A sex/age distribution accounted for the net effect of births, development and deaths. The CH4&nbsp;yield was based on calorimeter measurements. The average bison's weight, feed (dry matter, DM) intake and emissions were 411&nbsp;kg, 3.4&nbsp;t&nbsp;DM&nbsp;head&minus;1&nbsp;year&minus;1&nbsp;and 72&nbsp;kg&nbsp;CH4&nbsp;head&minus;1&nbsp;year&minus;1, respectively. The historic herd's emissions were 2.2&nbsp;Tg&nbsp;CH4&nbsp;year&minus;1. On 1 January 2008, 36.5&nbsp;M cattle were located in 10 American states occupying the historic bison range. Cattle emissions were 2.5&nbsp;Tg&nbsp;CH4&nbsp;year&minus;1, estimated using an IPCC Tier 1 method, adjusted by comparison with a mechanistic model and food gathering energy required by 77% of the cattle fed by grazing.</p>
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