Scott, I wanted to help you determine why your photos were blurry, and looked at the exif embedded in your photos to get the camera settings for these 2 images. The second photo was taken with a shutter speed of only 1/25 sec. which is too slow to get a sharp image under those circumstances. The first image was 1/200, and while that gives you a much better chance to get a sharp image it is still not fast enough to prevent noticeable motion blur unless the camera and subject are relatively still. Is your 70-200 f/4 lens the IS version? IS will help, but with enough camera movement it still won't guarantee a sharp photo. In light like that, bumping the ISO to 800 or even 1600 would have helped you to get enough faster shutter speed to help a lot.
Did you notice where the camera focus point(s) were on these shots? When there are so many objects such as brush, limbs, and grass between you and the subject sometimes the camera will lock focus onto to unwanted objects.
While lenses and sometimes the sensor do need periodical cleaning, I think low shutter speed and perhaps a little bit of camera shake (movement) were the mostly causes for your photos to be blurry.