May is Undoubtedly one of the best months of the year for birding in Doñana. The influx of birdwatchers is not as numerous as that in April, temperatures are better and the chance of rain much lower, although you should take in account not to coincide with the celebration of El Rocío Annual Festival, when the tours to the park are suspended and it’s difficult to move around in the area by car and get accommodation unless you pay an exorbitant price.
Spring moves restless across forests and marshes in Doñana. In the meadows among the trees in Coto del Rey Pine Forest green is fading away now day by day and grasses dominate over other plants, although the wild gladiolus (gladiolus italicus), the Italian bugloss (anchusa calcarea), and the large Spanish iris (iris xiphium) stand out of the green putting notes of colour in it.
Black kites and booted eagles continue their nesting duties and are often seen perched by their nests. With a bit of luck we will be able to see their chicks; they are just small balls of white feather, but in a few weeks they will be exercising their flying technique through the skies of the forests. Antlion traps abound in the roadsides and sandy areas with little transit of animals and vehicles. Wrens, Sardinian warblers, Cetti´s warblers, short-toed treecrepers, chanffinches, serins, goldfinches, greenfinches, great and blue tits, fill the woods with their songs. Rollers and orioles still pass through Doñana, along with alpine swifts. In forests and meadows abound other species like bee-eater, woodchat shrike, red-necked nightjar, rufous bush robin and nightingale; melodious and Isabelline warbler also become very common.
In Matasgordas Cork Oak Woods is the halimium halimifolium which dominates now filling with its yellow flowers the undergrowth; the long stems of the echium gaditanum and those of the armeria gaditana are the only ones who discuss its dominance. It is now when most of female red deer leave the protection of the herd to give birth to their fawns in a hidden spot of the woods and when first partridge chicks come out.
Large areas of the marshes have dried out by now as temperatures rise. Here many thousands flamingos occupy the shallower areas, feeding on small invertebrates whose density increases as the water level drops. It is an impressive sight when they all fly away coloring the marsh in pink. Below them large numbers of glossy ibis, purple herons and cattle egrets on their way to the breeding colony, loaded with food for their chicks. Black-winged stilts and collared pratincoles share a plot of dry clay near the water edge, defending aggressively their nests from black kite and gull attacks. The first chicks must be about to hatch, same as the small numbers fo Kentish plovers and lapwings who share with them the changing borders of the dry islands of the marshes. Pintail sandgrouse begin with reproductive tasks so it becomes easier to spot them. It is still possible to see numerous species of waders on passage and also the last short-toed eagles, black storks (normally young ones), garganeys, pied flycatchers and wheatears.
Species like, little bittern, squacco heron, purple heron, cuckoo, collared pratincole, gull-billed and whiskered terns, increase their numbers. White-headed duck, red-knobbed coot and marbled teal are common sights at Caño Guadiamar and Dehesa de Abajo lagoon. Other species like black-necked grebe, red-crested pochard, avocet, purple swamphen, great reed warbler, reed warbler, Savi’s warbler, red-rumped swallow, short-toed lark, and yellow wagtail become very common and the chances to see them increases in lagoons, caños and marshes.
It is now in May when the bulk of reproductive activities take place in Doñana and the breeding colonies at José Antonio Valverde and along Caño Guadiamar are a cacophony of squawks and cries with the constant coming and going of birds. The number of chicks in the colonies increase day by day. The views of the colony from inside the visitor centre are great, making it one of the most interesting experiences in Doñana throughout the year. Black kites and marsh harriers fly over the colonies daily in search of an easy snack. In the open waters at Caño Guadiamar great crested grebes and little grebes are still carrying their babies on their backs and they will do while their size permits. Sharp-ribbed salamanders and frogs abound in the waters of the channel but only to see on the peaks herons and egrets before eating.
This is when the rice paddies start getting flooded. Cattle and little egrets, gull-billed terns and whiskered terns are normally the first to arrive to feed on the small insects that move away from the flood.