Lovely expressions (especially on your bird character)! The bottom picture with the skateboard is coming along nicely, though personally I'd switch the right foot (my view) to a bit smaller depending on the prespective you're going for, or if you're just wanting it to be a front view maybe extend the length of the skateboard a bit to match.Great work overall!
Very nice linework. Very very clean. The background on the skater pic feels a tad bit off perspective wise. Perhaps it's because of the weird view I get on my cellphone, but that's just my opinion. The coloring is very appealing.