Men are targeted by ISIS more often. It seems logical that men would be the ones who'd be most likely to flee while women and children would stay. It's usually what happens when there is an invading force using forced conscription. Men flee into the woods, deserts, etc in higher numbers. That said, it's impossible for us to know why there exists a discrepancy without a census Syrian population. At least, one that isn't from the early 2000s (that's when their last census was taken). It may have been that men already outnumbered women before the crisis substantially (the last census suggests 106 men per 100 women). Likewise, poverty may be an issue. In Muslim countries, women and children tend to be consistently among the poorest. That may cripple their ability to actually leave Syria. Men, being the ones with jobs and income (whether single or married) seem to have higher economic possibilities and thus would have an easier time leaving Syria.
Well, let's think about that for a minute:
1. Who's doing the fighting in Syria against the Assad regime? The forces waging war would be predominantly men would they not? As such, wouldn't that cut down on the actual number of Syrian men fleeing Syria? And wouldn't that cut down on the number of Syrian men of fighting age who are still alive and not included in the 200,000 or so Syrians who have been killed in the conflict to date?
2. It's possible that a disproportionate number of females and female children have been captured by ISIS to use as slaves and as enticement for single men to join ISIS but would they be in such great numbers that it would skew the numbers fleeing to Europe by such an extent - 62% to 38%?
3. By UN accounts, there are 4 million refugees from Syria to date. Do we know the numbers of men, women, and children in the UN funded and operated refugee camps in Jordan, Lebanon, Turkey and others? It's possible, and I don't have the answer, that many well meaning men of fighting age dropped their wives and families off at refugee camps in these countries and then fled to Europe in the hopes of establishing themselves there so that in the future they could sponsor their families to join them. That's putting an extremely positive spin on the skewed numbers, but knowing how some men have come to Canada on work permits and then sought landed status and then sought to sponsor family members - parents, wives, children, etc. - it is very possible that even the majority of fighting aged men fleeing to Europe are doing it to set up a better life for themselves and their families. That said, countries like Canada and the US can't take too many chances in that regard under the circumstances.
4. It's quite clear that the Syrian regime is opposed to those in the US led coalition that wants to see them ousted. As such, it's unlikely that this regime would provide credible security screening for Syrians, particularly fighting aged men, to the UN and/or individual countries from the coalition. They're likely to give a pass to enemies of the regime who may have been criminals or terrorist sympathizers, etc. so it's virtually impossible to get a good picture of what the history of single men of fighting age might be. Children are easy to clear and their mothers likely as easy. That's who we should be saving through refugee relocation until the situation is a little more settled over there.