Have a theory that once a name becomes unisex it's only a matter of time before it goes all-female, parents shunning the name for their boy children. "Leslie" is a clear example.
But "Robin" has been unisex for at least 100 years, and doesn't seem to be shifting; at least that's my impression, though the baby-name sites tend to list it only as a girl's name, and as a girl's name its popularity has been plummeting since the '60s. BUT: when I type the name into Google, Google suggests the following in order of popularity: Robin Williams (male), Robin Thicke (male), Robin Hood (male), Robin Meade (female), Robin Trower (male), Robin Wright Penn (female), Robin Givens (female), Robins Federal Credit Union (n/a), Robin Tunney (female), Robin Söderling (male). So it's clearly still a viable male name, unless its viability has ended too recently for me to notice.
EDIT: Here's graphic info for the popularity of Robin as a boy's and girl's over time. It's been more popular as a girl's name than a boy's, but the rise and decline in both seems proportional (boy's name peaking slightly earlier, which means parents of boys fled the name slightly earlier than parents of girls). Here's the same info for Leslie, and the difference is drastic, going from almost all male in the 1920s to almost all female in the 1950s. And for the hell of it, here's the info for Jordan, which went from all male in the early '70s to one-quarter female in the mid '80s, and it's been holding proportional ever since then (which challenges my theory; maybe things are changing). I've got more info in the comments.
But "Robin" has been unisex for at least 100 years, and doesn't seem to be shifting; at least that's my impression, though the baby-name sites tend to list it only as a girl's name, and as a girl's name its popularity has been plummeting since the '60s. BUT: when I type the name into Google, Google suggests the following in order of popularity: Robin Williams (male), Robin Thicke (male), Robin Hood (male), Robin Meade (female), Robin Trower (male), Robin Wright Penn (female), Robin Givens (female), Robins Federal Credit Union (n/a), Robin Tunney (female), Robin Söderling (male). So it's clearly still a viable male name, unless its viability has ended too recently for me to notice.
EDIT: Here's graphic info for the popularity of Robin as a boy's and girl's over time. It's been more popular as a girl's name than a boy's, but the rise and decline in both seems proportional (boy's name peaking slightly earlier, which means parents of boys fled the name slightly earlier than parents of girls). Here's the same info for Leslie, and the difference is drastic, going from almost all male in the 1920s to almost all female in the 1950s. And for the hell of it, here's the info for Jordan, which went from all male in the early '70s to one-quarter female in the mid '80s, and it's been holding proportional ever since then (which challenges my theory; maybe things are changing). I've got more info in the comments.