Western Cleddau: Sand Martins and Kingfishers

I have spent a fair time on the river in the last c.3 weeks (the curse of the elusive sewin), and have been very pleasently surprised by the river's water (and so weed) quality, and the massive variety of insect life. The most obvious beneficiary of this is the large number of swifts seen over the adjoining meadows, and the colonies of sand martins, which appear to be well-populated. The largest of these that I have found has 30+ holes, and is where the river does a sharp turn north of Crow Hill (GR 951 179).
As reported elsewhere there is also a very healthy population of Kingfishers: based on my exploration of the river between, roughly, Haverfordwest and Wolfscastle, I would estimate that the population could easily be one pair per kilometre of river, and possibly an even higher density on the lower reaches. Of the birds that I have been seeing, over half have been carrying fish, so there should be a good number of young to be seen on the river in the next month or so.