Purple Heron (Ardea purpurea)
The Purple Heron (Ardea purpurea) is a passage migrant to the Canaries, with records from all islands except El Hierro. It is classed as a P2 migrant in the checklist of the Field Guide to the Birds of Macaronesia (Eduardo García-del-Rey, Lynx Edicions), meaning that the estimate of probability of observing this species during migratory periods is "medium", in a grading system where P1 indicates "high", and P3 "low" probability.
From my own experience on La Palma, I would tend more towards a P3 rating ("low probability"), since this is only my third sighting of Ardea purpurea on the island, the first being back in April 2011, the second in April 2014. On the first occasion two birds were seen at irrigation ponds in Las Martelas (Los Llanos de Aridane), and photographs of one of the herons appeared in the April 20 blog post. The 2014 record was at an irrigation pond in Tazacorte.
The present individual was first encountered at an irrigation pond in Tazacorte on March 31, when the second and third photos in the present post were taken.
After checking the area again on April 1 and 3, the Purple Heron was eventually relocated this evening, April 4. On this occasion, various images of the bird in flight were captured, including the one above.
Also present on the island at the moment is a Black-crowned Night Heron (Nycticorax nycticorax), which I accidentally flushed on April 3. The Night Heron and the Squacco Heron (Ardeola ralloides) are also classed as P2 migrants to the Canaries in the above-mentioned field guide, but in contrast to the Purple Heron, I have recorded around 8 of the former species and 14 of the latter on La Palma in the same period (2009-2015). Almost all sightings have been in the period April-July.