I call BS. There is an opportunity cost for passing up a chance to help some seabirds. Most people don't go through a given day being presented with lots of opportunities to save different numbers of seabirds. If they were, they'd do the math. Most people wouldn't assume that there were a dozen different seabird charities who are all pledging to help different numbers of seabirds because that's not the world we live in. If it was, people would process this differently. When people are presented with options, such as in stores where different brands compete for shelf space, they do tend to do the math