Ninjas in Boston?

I'm not sure why ninjas have decided that Boston is their home town, but I have seen so many ninjas in the past few days that I thought I should let the rest of the world know about them. My theory is as so: It is so cold right now in Boston (well really the entire New England area but I live in Boston, and have not been outside to see if the ninjas are as bountiful, so we will stick with Boston as their home town) that the ninjas must feel that we are so weak that they no longer need to turn invisible and kill us with numchuks and ninja stars. Instead they are free to walk around the streets in plain sight. Unbelievable. If the ninja elders knew what was going on in this progressive ninja city they would not approve; I assume. Another part of the theory is that it gets darker here in the winter quicker than further south so they feel more comfortable. Even if they aren’t completely invisible they are not easily noticeable.
For your consideration I have posted a rough sketch of what I consider to be the most common forms of ninja walking the streets of Boston (click on the image for a larger veiw):

The first sketch on the left is of a female ninja as can be seen by the thin eye brows and lighter shade of gray for the eyes. The second is a pretty common ninja that has holes in the mouth area to help him breath. I’m not sure of the reasoning for this other than this type of ninja must do a lot of running and jumping from roof-top to roof-top. The third is drawn as a male ninja but actually appears in this area as both genders equally, and I call this ninja the “Snow Ninja”. Snow ninjas tend to wear big jackets with the fake fur lining in the hood with a scarf wrapped around their face up to the nose at which point the eyes are visible and then the rest of the head is covered by secret, proprietary, ninja garments. Please, if you have any more information on the ninja concentration in Boston please let me know.

Update: I have been told that these are not actual ninjas but instead just stupid Harvard/MIT kids that are trying to prevent the cold from reaching their faces as they walk to class. Of course that is ridiculous, I know what a ninja looks like first off because I was raised in the wild by a ninja for a year when my parents couldn’t look after me. And secondly, how dare you second guess me! This is my blog damn it.