atively and return <code>NULL</code> if parameter fitting fails for <em>any</em> of the focal species passed as arguments, printing an informative message about which species failed to fit.</p>
<p>Importantly, bounded methods can be very sensitive to the initial values and bounds, so, as in any numerical optimization problem, you should double-check the values obtained, at least by computing standard errors on your parameters with an adequate number of boostrap samples, and preferably by performing sensitiv