So you find drawing animals in real life a little hard? I agree. Just when you start a sketch they move! How can you get better at sketching, and sketching fast. I always suggest practice, practice, practice but how? Well going outside to journal is always my first answer but I found a website that allows you to work on quick 30 second drawings.
You have to get over the idea that every drawing needs to be finished. Sketching is just that, sketching not a finished piece. Quick sketching allows you to get the "line of action" feel and general character of your subject. Many people hate have a sketchbook with unfinished drawings but you have to remember this is NOT a portfolio, this is not what you take to a client to get a job. This is your workbook, so to speak.
I will be putting together a tutorial on how to make quick gesture sketches soon.
Below you can see some 30 sketches, then some 1 minute, then finally a 5 minute sketch.