Scout Scar: mining bees, fly orchid, mountain everlasting

Mining bee

Mining bees responded to bursts of sunlight on a day of louring cloud, flying over entrance holes the colony had burrowed in soft soil mid-track, quickly disappearing below ground.  On my second day of bee-watch I felt the rhythm of their behaviour and was poised to photograph the moment a bee approached its entrance. If I listened intently I could just catch the vocalisation of hovering bees.
Some years at this season, in warm dry weather,  neat holes appear at intervals on the track where there's a south-facing slope.  1st June saw rain much of the day, sometimes heavy showers, so what happens to the colony then? Holes appear, then they're gone. Soil all around their entrances has been finely worked, with little mounds made during excavation.  What we see and what we do not see. The bees are colonial, communicating with each other, somehow working together- so do those entrances link up and is there an underground chamber- what's the structure? And if they store pollen, have eggs and larvae, will other insects predate them-  one or two ants show in my images.

Every man and his dog who walked this way at the end of May must have walked through these colonies of mining bees. I wonder how many noticed them.  Often, walkers detoured to avoid us, mid-track and intent on studying bee behaviour.  Being mid-thoroughfare does not seem to trouble the bees and they went about their business seemingly undisturbed by our presence.  Tiny bees, hovering low over their holes,  the buzzing sound so faint you'd  only hear it if you stopped to study them.

The mining bees have black wings and antennae, a bright yellow abdomen and yellow legs.  Their bodies seem dusted with pollen. It's suggested they're hawthorn bees and the shrub is common beside the track, flowers now somewhat fading.  I have not seen them foraging and they're so tiny they'd be hard to spot. 
On Saturday I photographed tiny, slender bees, perhaps males.  Next day, Sunday, I think I have the females- larger and with a larger, yellow abdomen. 
Are they mining bees, or leaf-cutters?  ID is challenging.
I wonder if they attract predation. I notice a few ants close by.
​Up on Scout Scar escarpment the sky grew dark, with louring clouds.  Hoary rock rose is heliotropic, its flowers closing until the sun shines.  Common rock rose is at its most abundant and lavish, flowers fully open. So the two species are easy to distinguish on such a day.
Close by the track were about four fly orchid. And a few mountain everlasting fully open, some budding and to come.  

More detective work for a nature writer is afoot.   The limestone grassland of Scout Scar has a scatter of gorse, juniper, blackthorn, rose, hawthorn. It's habitat for nesting birds and there are skylark and meadow pipit that are ground-nesting- not much of a nest, just something amongst grass tussocks with a degree of shelter.  The ground has a scatter of anthills.  One, just one, was littered with egg shells, from some five eggs.  One or two larger, buff coloured with brownish flecks. And smaller bluish shells.  A few feathers, saturated after rain, were strewn beside the shells.  Looking closely, the picture was grisly. There were dark mystery objects.   Were they pellets disgorged by an owl?  Or scats, something excreted.
And what creature had brought predated eggs to this spot, and what was the timescale.   If this debris had been there for some days it would be dried out, saturated, and decomposing.   I've seen stoat in this location.  There could be owl,  will be corvid, magpie, and fox.
Naturalist Jeff Holmes thinks fox is the likely predator here.  Feather shafts have been chewed, typical of a mammal predator. Although a fox might eat the whole egg, leaving no shells.