why are the majority of fursona species canines?

familiarity i would assume, also wolves and foxes show up a lot throughout history in folklore, etc. probably due to their close resemblance and behavior to that of dogs. also people are just boring and since its already the most common fursona species seen they just go with it as well

There SHOULD be more birds!!

I'm an arctic fox and golden jackal mix so I am part of the problem =C

Sure it might feel repetitive, but I don’t see the harm in too many of a species. You can put a whole lot of creativity with each one, then. 

Maybe there are more uncommon species than you think out there, the more well known furry content creators and artists might have common species as their fursona, but I’ve encountered a lot of reptilian, avian and even bug fursonas online. It’s where you look I would think. 

 es el mas común, cuando piensas en un furro casi siempre se te viene las típicas imágenes de furros con apariencia de perros, bueno yo creo que debe de haber mas animales en la comunidad furry :D

Because am dog. Bark bark!

But seriously, I went through a ton of different species before landing on a regular ol' dog. Maybe cause I'm a regular ol' guy. I have a few other fursonas, one is a capuchin, another a hare. Past fursonas include other dogs, dutch angel dragon, fluffy monster, and likely a few others I simply don't remember.

Another answer would be because a lot of furries want to fit in with the group since they don't fit in with other communities, or maybe they don't care much about animals and go with one of the few they do know. Some furries are just in the fandom to try and get clout, others don't actually care about the animal they choose to represent themselves with. Honestly there's a lot of plausible answers to your question, I guess it's a case by case basis. *shrug*