If you had to be an endangered animal, you’d be better off as a tiger than a toad. If you were a tiger, filmmakers might cast you in wildlife documentaries and journalists might write heart-rending stories about the disappearance of your kind. Your furry mug might appear on magazine covers and postage stamps. And conservation organizations just might make you their flagship species, a stand-in for all the critters whose survival is threatened. In other words, if you were a tiger, you might have a fighting chance of at least making humans care about your predicament.

That’s a taller order if you’re a toad, an animal that wins over few human hearts. Instead, we prefer the so-called “charismatic megafauna,” funneling our emotional and conservational energies into species like tigers, lions, elephants, dolphins, pandas, and the like.

A number of psychologists and biologists have begun to uncover why some species appeal to us more than others, identifying a number of factors that make certain kinds of critters especially attractive. For instance, we have a soft spot for our fellow mammals, and we prefer big beasts to smaller ones. We’re also strongly attracted to “neotonic,” or juvenile-looking, features. The youngsters of many species have large heads, large eyes, big foreheads, and snub noses. Human infants have these characteristics, as do puppies, kittens, and all sorts of other critters that we find cute. In some species, adult animals retain features associated with youth–such as oversized eyes–and we’re naturally drawn to these neotonic faces.

An animal’s coloring may also, well, color, our perceptions. In 2006, David L. Stokes, a researcher at the University of Washington, Bothell, published a paper on penguins, which look more alike than different, all dressed in their matching black-and-white tuxedos. Stokes found that even a dash of color could win us over; according to his research, we seem to prefer penguin species that have a dash of warm color–red or yellow–on their bodies to those that are entirely black and white.

Our preferences for certain species over others have serious implications for conservation. Studies have shown that charismatic megafauna attract more than their fair share of conservation attention and funding. As Stokes put it in his 2006 paper: “Much of the world’s biodiversity will survive only if humans choose to protect it. Given that people are likely to protect what is important to them, human preferences will be important determinants of many species’ prospects for survival…”