ELEMENTFIRE

Hi all, I was capturing this sunbird with my XT-5 and the fujinon 70-300mm. Somehow im struggling to get nice and sharp results. Any advice would be appreciated. Could this be due to the SD card or due to lens not being clean enough? Or is the focus just poor? Settings used: Shutter Speed: 1/1000 sec. Aperture: f/5.6 ISO: 4000