@
Sirindu
About posting screen shots, this might be easier for you then using another website that you are not signed up for; I use this very website to post all of my screenshots. Just go to your profile page, go to your photo albums and click to it's page, then upload your screenshots into a folder and then you can just post image links using the url's for the image from this site.
That's how I do it and it only requires me to use one website, (the best one of course) this one!
As for searching for finding Zubats in general. I find them at all times of the day. The only reason why I find them more often at night is because I play mostly at night. Zubat are a common pokemon in my area but I would say they are lower on the list as a common pokemon.
Despite that it seems Zubat don't care about what hour of the day they are out and about in my area... I have noticed that other pokemon do care... For example, there is an Onix who spawns around my apartment but only in the super early hours of the morning (2am-4am) and there is a Lapras spawn point in the middle of town but I've only seen it spawn twice and it has always been at around midnight and 1am.
So although I feel like Zubat do whatever they want at any time, I really think there is some merit about time affecting other spawn rates.