Here is a run down on the gear I use in the field for anyone who is curious. I am a “Pentaxian”, having purchased a Pentax MX 35mm SLR as my first serious camera in the late 1970s. I recently added a Nikon Z8 mirrorless camera to my equipment and swap between the two systems depending on what I am doing.
Bodies:
Pentax K3 Mark III. I am really impressed with this camera, especially the viewfinder, autofocus and overall capability for bird photography. It’s a solid cropped sensor DSLR with the really great feature of being weather sealed. It also performs well at higher ISOs and that is a benefit when field conditions are poor. It is my workhorse camera.
Nikon Z8. It has the benefits of advanced autofocusing and subject tracking found in mirrorless cameras. It is not as rugged at the Pentax and has poorer battery life. But it produces excellent shots and can do faster bursts for catching birds in flight. I tend to use it when I am photographing in specific situations.
Lenses: I use two long lenses. The Pentax HD D FA 150-450 mm f/4.5-5.6 DC AW is my go-to lens on the Pentax body. It is light enough for handheld shooting (about 8 pounds with the body and battery grip) and is weather sealed. The Nikkor 180-600mm zoom is what I use on the Nikon body. It is a bit lighter than the Pentax and has an internal zoom. The Pentax lens is more weather resistant. The effective lengths are pretty close since the Pentax is ASP-C and the Nikon is full frame.
Miscellaneous Field Gear: Vortex Viper 8×42 Binoculars and a BlackRapid Double Breath Harness. The harness can carry two cameras. I rarely carry two but the double shoulder straps have attachment points for the binoculars. It keeps me from getting strangled with two sets of straps, one for the camera and another for the binoculars. The harness also has excellent clips for securely hanging the camera at your hips.