Is it mating season for birds right now? I live near Toronto?

I live out side of Toronto. Chirping doesn't always mean that they're mating, they could be just happy or communicating. Late may to the end of June is mating season for some of them.

Birds in general, depending on where, mate in the Spring when the weather warms up.  Some will have two clutches.   The 'chirping' is ujsually to do with calling for a mate/protecting their territory.

That just means the days are longer, sun is out more... they know warm weather is ahead.  I get chirpier too with summer coming.

unless they mate twice in toronto then they are just having a good time 

I would think it is a bit late.  The eggs should be laid by now, and even hatched for most birds near Toronto.  They will certainly be lots of chirping between chicks, and parents though!

I am a huge lover of the birds. I am feeding squirrels, chipmunks, and all kinds of birds. It is mating season for some birds while others are about to be hatched. I have birds chirping and flying all over my house and I love it. If they are chirping loudly, they may be calling to other birds or gathering nesting materials. 

Yes.  I am south  of   you in the states and  have a pregnant dove outside my window.  I actually saw them mating.  There was also a scuffle when another male dove tried to get in on the action.