Hi BillD, I've been to this area a couple of times, but not in May - I have copied and pasted the relevant parts of a couple of posts from my trip reports for the relevant days; hopefully this is of a little help:
Hoya de Baza & Hoya de Guadix (late April 2016):
"From the main road, seeing the usual roadside / settlement type species seen yesterday on the way, I took the Canal de Jabalcon service road as a detour towards Benamaurel. A route I thoroughly recommend when you can drive along as slowly as the car will manage with the windows down looking and listening for anything interesting. My first stop was right at the start of the track to listen to the rattling of both Corn Bunting and Serin - a nice comparison - in the rough fields and track-side trees along with Linnet and the usual common species. A raucous call alerted me to a Great Spotted Cuckoo flying over close by. Patches of trees further along also added singing Nightingale and Blackcap. As the landscape became more arid Larks, Stonechat, Black Redstart, Rock Bunting, Iberian Grey Shrike and Northern & Western Black-eared Wheatear were all seen and Cuckoo & Hoopoe heard only again. Overhead a single Alpine Swift was noted in the flocks of other hirundines.
Beyond the underground rock-cut dwellings where cultivated land becomes dominant a small man made reservoir had a few each of Little Grebe, Black-winged Stilt, Common Sandpiper & Redshank around the edges plus a small flock of Yellow-legged Gull. There were also a couple of Great Spotted Cuckoo around the edges that gave even closer and better views and Red-legged Partridge in the fields. Further on in a more rocky section I stopped on hearing and seeing a group of 3 European Bee-eater fly over and whilst watching them a Roller flopped out of a nearby shrub and flashed vibrant blue as it joined another on a cliff. While scoping this pair I also picked out a Little Owl in its roosting hole on the cliff face.
Further drives along the minor roads on the route Benamaurel-Castillejar-Galera-Cullar produced similar species.
I then returned to Hoya de Guadix doing the route I did in October in reverse (Cenascuras-Gorafe-Alicun-Fonelas-Benalua). I had apparently missed feeding time on this occasion but there were still a few European Griffon Vulture around the feeding site cliffs. I walked along the track towards Gorafe thinking the habitat looked particularly 'larky' but saw only Crested / Thekla types. But I did add Black Wheatear and Sardinian Warbler for the day and had a small flock of Red-billed Chough enjoying the thermals off the outcrop edge and a passing Raven."
Hoya de Guadix (late October 2015):
"Cracking weather again today so I took advantage of it and headed to the high plains east of Granada with the 'usual species' seen on the journey. I took a slow drive around the minor roads in the Hoya de Guadix area, stopping & scanning where possible and the habitat looked promising. I had Blackbird, Chaffinch, Goldfinch, White & Grey Wagtails and Cetti's Warbler where the vegetation was more lush at a couple of water-course crossings plus Crested / Thekla Lark in the drier areas. But the birding was proving difficult on the move so I was on the look out for a place to stop & set off on foot. As I drove up out of a valley south of Gorafe, thinking the ridge may be promising, I saw a car park and pulled in. It proved to be a parking area for visiting a series of Neolithic dolmens so I walked the trails seeing Sardinian Warbler, Black Wheatear, Blue Rock Thrush, Red-billed Chough & Crag Martin in the scrub & around the crags.
A quick scan of the opposite side of the valley showed a flock of 20 or so Griffon Vulture circling distantly and relatively high up. Near the end of the route I heard a noise from the top of the adjacent near-by crag and looked up to see what it was, to have 10 or so vultures fly in very low overhead and land on the ridge. They continued to float in from all around, so low over that the wind could be heard whistling through their wings, and a slight change of position let me see a pile of meat had been dumped on top of the crag and they were swooping in to feed. More and more came in and the noise and squabbling increased. After 20 minutes or so of constant action it appeared that most of the food had gone and while some latecomers were still arriving and a few were sitting on the cliff top and digesting many of the vultures were taking off and moving up the valley and then circling back overhead to gain lift. It was not easy to get an accurate count, given the constant coming and going and with birds circling in all directions, but I estimate there were 80+ in the air above me as I lay back on a rock looking directly overhead. I started looking for other raptors in the kettle and picked up 3 Golden Eagle but they unfortunately stayed high up and drifted off. Eventually the Vultures had dispersed in various directions with only a few to still be seen in the distance. So I headed up to another car park on the ridge top and walked to the feeding station area where just part of a shoulder blade and the top end of a large leg bone was all that was left; with a few Magpie, Jackdaw & Carrion Crow lurking around on the surrounding plain, hoping for some scraps. Best birding experience of the trip by far!
Driving the area further only added a small flock of 3 Lesser Kestrel catching, presumably, insects in the air over a scrubby field."
The sites described were found using 'Where to Watch Birds in Southern & Western Spain' by Garcia & Paterson.