I've been trying to photograph these birds since June. They usually perch in the same spot, but it is just a bit too far away, and also a bit too shaded. This time I used a tripod, and the sunlight was just right.
Update 5/9/2021:
New camera and lens arrived this weekend, so I went back to take a comparison photo at an effective focal length of 800mm. The conditions were not ideal - it was very hazy along the ground, but there was also strong sunlight. The photo above had to be taken using a tripod, however the new camera has very fancy image stabilisation and I didn't bother with the tripod today.
