<p>Data from this study on <i>Dosinia</i> was combined with data from van Gils <i>et al</i>. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136144#pone.0136144.ref014" target="_blank">14</a>] on other non-toxic prey species. Adding the current data to the regression derived by van Gils <i>et al</i>. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136144#pone.0136144.ref014" target="_blank">14</a>] slightly changes the regression line (though not significantly; from dashed to solid line), but greatly reduces standard error (from light to dark grey area). Parameter estimates are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136144#pone.0136144.s006" target="_blank">S1 Table</a> (model 3.1). Regressions are linear regressions on log-transformed data. Note that van Gils <i>et al</i>. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136144#pone.0136144.ref014" target="_blank">14</a>] averaged gizzard mass measurements per bird, whereas we estimated gizzard mass in each trial by interpolating measurements.</p
