The number of Buteos varies depending on who you ask. I've recently been keeping my entire list in eBird, and there 29 species in the genus Buteo according to that listing regime. If you count all the subspecies and groups you are able to 'designate' a bird as in the program, however, the number climbs to 63, including the generic entries such as "Red-tailed Hawk" with no further specification. This level of variability exhibited within the genus can really make some species a nightmare for field birding. In fact, one species, the Variable Hawk (Buteo polyosoma) was once considered several different species before genetic testing showed that there were merely 20+ color morphs! In the state, thankfully, there are typical 'morphs' for each population, and when seen prove extremely easy to identify. An example of this would be a Swainson's Hawk: there is really no other bird like it in much of its range, and regular 'light-morph' birds that I usually see in the deserts of Colorado and Utah rarely make me take a second glance to confirm them. Things become slightly more complicated as variability is taken into account, however, and the dark-morph birds I had at Independence Rock in Wyoming made me glance at my book just to be sure. Luckily, Buteo is pretty well covered genus in North America, and many guides are available showing the telltale marks for birds of virtually any population and color morph.
The comfort of this safety net of field guides from every angle has slowly slipped away for me over the years. when I was in South America, there was a juvenile Buteo in the jungles near Baños, Ecuador, and we were in no way certain of what to make of it at the time. It wasn't until several months later after I was back in the states that I finally figured out it was a young White-rumped Hawk (Buteo leucorrhous) outside of the typically expected elevational range (full checklist here). Even then, I was reliant on guides that were not available to me in the field, and that I did not even know existed while I was scouring my Ecuador field guide in the damp jungle.
This feeling of helplessness of hawks quickly returned to me as I arrived in South Africa. So far, the most common bird for me has been the "Steppe" Common Buzzard (Buteo buteo vulpinus), considered by my field guide to be separate from the nominate Common Buzzard. Indeed, some insular subspecies of this hawk have recently been upgraded to full species status, and some of the more distinctive mainland forms may follow in the near future. My knowledge with these birds is limited at the present time, and I mostly know that if a see a variably brownish bird flying over campus of the open karoo near Stellenbosch, that opening my book will inevitably lead me to this hawk.
While on the slopes of Stellenboschberg, I encountered yet another Buteo which was completely foreign to me but, luckily, extremely distinctive: the Jackal Buzzard (Buteo rufofuscus). These birds have red-tails much like the hawks I'm familiar with at all, but are ink black under the wings and across their mantle, making them extremely distinctive.
Today, in an attempt to beef up my world hawk list, I ventured through an extensive Eucalyptus plantation near town (complete birdlist here). My goal bird was one of two Buteos: the South African endemic "Forest" Mountain Buzzard (Buteo oreophilus trizonatus) and the so called "Elgin" Buzzard. The "Elgin" Buzzard, more commonly called the "Mystery Buzzard," is an enigma. A pair of largely rufous hawks was found nesting near Table Mountain a few years back, and now these birds are common in plantations and farm areas in extreme southwest South Africa (and according to the website listed below, occur "around Jonkershoek near Stellenbosch)." As of yet, no one is really sure where they come from either, with hybrid origin being one possible explanation I have read. So, when I finally did scare up a pair of Buteos, I got extremely excited about what they could be, but through the minimal views and even after photographing them I am left shaking my head. Their wing pattern was similar to that of a "Steppe" Common Buzzard, ruling out "Forest" Mountain Buzzard, but the head was pale, which did not necessarily line up with the Common Buzzards I had seen previously. Similarly, "Elgin" Buzzards are usually pretty uniform and usually largely rufous, which, though uniform, this bird was not rufous. Classes start tomorrow, but as soon as I am able I intend on heading out and looking for them again. In the meantime, I have a lot of studying I'll have to do for classes, and a lot I will have to do before I can fully appreciate and understand this variable genus.
In the meantime, some homework for whoever reads this blog: what do you think this hawk is?
Cape Mystery (Elgin) Buzzards: http://mysterybuzzard.blogspot.com/p/identifying-mystery-buzzard.html
"Steppe" Common Buzzard photos: http://www.google.co.za/search?q=steppe+buzzard&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=GY4uT_C8JcPBhAfo0eTjCg&ved=0CD8QsAQ&biw=1280&bih=685
"Forest" Mountain Buzzard photos: http://www.google.co.za/search?um=1&hl=en&biw=1280&bih=685&tbm=isch&sa=1&q=forest+buzzard&oq=forest+buzzard&aq=f&aqi=g1&aql=&gs_sm=e&gs_upl=1801l1933l0l2792l2l2l0l0l0l0l200l200l2-1l1l0