Shot this crow this morning with full light. Colors popped out from what is normally a very black crow.
Not a professional birder but the5DmIV - Sigma 150-600C at 600mm combo with 50% crop and little Lightroom PP (vibrance and sat +10/+5, shadow recovery and some other tweaks), yielded a nice result
(hend-held at 2000ss and 1250ISO )

(Download)

If you qualify "walk-about" lens as the one that seems to stick to your camera when out and about....70-200 F2.8 IS II.... I know, I am weird...Weights a ton but I just can't seem to sacrifice that dreamy bokeh, portrait-level feel and low-light capability that this lens creates. I have used it for street photography in Galway, Ireland and walks in the woods with wife and dog. It's a bit "obvious" for street photography but the 200mm reach allows for some discretion. I may look into a wide/long lens like the EF 28-300 f/3.5-5.6L IS USM as rmorrison1116 indicated ...wont solve the heft/discretion issue and may not be as good a low-light performer but will give me the wide end I lack in the 70-200mm. ...willing to sacrifice some sharpness...

#Canuck
We hold 3 of the top 5 sniper records.
...now if we could just pull our weight in NATO instead of letting the US carry the load... :-)

Canon 10-18mm is one of the best value for money....will be well under your 1k budget.
If you had FF i would have recommended the 16-35 F4 IS . Good corner to corner sharpness but in a crop your width will be equivalent to 24 - 35.

Beware the 10-18 will distort the image at the 10mm end to the point of not really being fixable in post. You will need to play with it to see what width-distortion is acceptable for you and your clients.

That is crazy good IQ at 1200mm , 400ss and 75% crop...even on a monopod.
Well done!

(And well done Canon :-)

Check Tony Northrup video on the 70-200mm shootout. In that review, he shows the effects of focus breathing and lens shaving.....pretty significant !

Auto=P&S.... Recommend a Sony RX100II.

I got hooked when I tried to recreate artistic images I saw online and discovered the joys of full manual control and composition, angles, blur, single AF pt,...get on your stomach, get on a ladder, shoot through leaves in the foreground, drag the shutter, play with speedlights, High FPS sports action from 200yds away etc etc
Keep shooting, keep learning!

..and by all means, shoot in Auto....on day 1..... and then never, ever again :-)

...or just save some money and use your iPhone....in good light, it will take as good a photo as a $3K camera on Auto posted on Instagram.....and yes, I use my Galaxy S6 to take the odd photo and post pics from it but it will never be able to do low light, do decent PP , or get bokeh like a good lens on a DSLR will allow.

...well...speak of the devil....
https://petapixel.com/2017/06/21/canon-6d-mark-ii/

5 axis in camera stabilisation? ...must only be for video otherwise Canon will have cut their lens revenue by 50% as everyone buys the non-IS versions of the L lenses.....

Wife wanted a DSLR. I got one. She never used it. I got hooked and now shoot weddings and events. Progression from entry level to mostly professional grade equipment.

Get an entry level, low cost refurb. Play with it. If you get hooked on photography....then buy the best you afford as next... per AK Grandpa feedback

Same position as you 6mo ago. I shoot weddings and needed the extra card slot for safety so needed the MkIV and expected the new 6dmkii would not have it. FPS, AF speed and low light AF, should be the deciding factors (along with articulating screen). I have it on my 70D but never use that camera anymore except for sports in full light. Other than crop reach that the 70D provides and the articulating screen of the new 6Dii the mkiv will be better or equal in every other category.

Wait for the 6Dii if you can but I am guessing that for you the articulating screen (go 6Dii) and FPS (go mkiv) will be the deciding factor. Check on the low light AF performance...guessing they will be close enough to make it a non issue).
IQ ratings related to DR and shadow recovery need to be considered also but expect them to be comparable also)
...and i will be torn betweem upgrading my 6D to 6dmkii (articulating screen) or upgrading my 70D to 7Dmkii/iii since I still shoot a lot of outdoor sports. (The 6D mki still has great IQ but effectively only 1 AF pt.....good enough for stills at weddings...will use the mkiv for everthing else....

No bad decision here...good luck !

Best at nothing....awesome at everything!
7fps ...good enough for sports....30mp....good enough for landscapes....4k crop....good enough for video...best AF system on the planet...(ok maybe its best at that). High ISO performance, low light performance , shadow recovery, great DR....outstanding!

Love it.

....now about that little flirtatious Sony A9 that keeps winking at me...

VR/IS is awesome at any focal length. The only time it has a negative effect is at "initiation" of IS you may get an instantaneous "jump" of the image in the viewfinder....after that it does have the effect of smoothing out the tracking. The SS will freeze the wingbeats of the bird and the IS is probably not going to do much for that...

...IS is best experienced for stationary objects at long focal lengths when you can lower the SS in low light to get good exposure and sharpness.

IS may cause viewfinder "jump" if IS activates during BBF while shooting fast moving targets. The longer the lens...the higher the sutter speed needed. If you are at 600mm on crop body....I would not go below 1200-1800ss when tracking a bird. If your technique is awesome....then 960 would be min (600mmx1.6). Stationary targets? How steady can you get :-)

My attempt at slang for referencing efficient, artistic and high quality post processing. I know I will trigger another round of debate if I mention SOOC vs PP .... (SOOC = Straight outta the camera, PP = post processing)...lets let the sleeping dog lie...

Thanks for all your replies. I recognize this is an old debate. The technology, business elements, media(s), access and "determination of value" are changing so rapidly that the term professional photographer has a broad set of interpretations. 50yrs ago, you needed a lot more technical skill than today to achieve a differentiated photo. There are still photographs that can only be achieved with a deep understanding of the technology and/or hours and hours of practice. With the internet, virtually any photograph you can think of can be conjured with a quick internet search. The concepts of professionalism, earning a living, deep technical understanding and artistry seem to be recurring themes. As the business evolves and video, blogging, youtube and other media become part of the photography world, "professional photographer" seems to be a term that has mostly lost it's meaning and/or sub-sumed within a broader "imaging services" theme. The good news is that "events" will always need someone with high-grade equipment, artistic talent, incredible planning skills, discipline, the interpersonal skills of a counselor and the financial and legal skills of a business owner...and the ability to adapt to the market.... hats off to those still earning a living...and you know who you are.