The largest of the Spanish marismas, and those best known to the authors, are those of the Guadalquivir. If the reader will look at a map of Spain, there will be noticed on the Lower Guadalquivir a large tract totally devoid of the names of villages, &c. From Lebrija on the east to Almonte on the west, and from the Atlantic almost up to Seville itself, the map is vacant. This huge area is, in fact, a wilderness, and in winter the greater part a dismal waste of waters. For league after league as one advances into that forbidding desolation, the eye rests on nothing but water—tawny waters meeting the sky all round the horizon. The Guadalquivir intersects the marisma, its triple channel divided from the adjacent shallows and savannahs by low mud-banks. The water of the marisma is fresh, or nearly so—quite drinkable—and has a uniform depth over vast areas of one or two feet, according to the season. Here and there slight elevations of its muddy bed form low islands, varying from a few yards to thousands of acres in extent, covered with coarse herbage, thistles and bog-plants, the home of countless wild-fowl and aquatic birds. In spring the water recedes; as the hot weather sets in it rapidly evaporates, leaving the marisma a dead level of dry mud, scorched and cracked by the fierce summer sun. A rank herbage springs up, and around the remaining water-holes wave beds of tall reeds and cane-brakes.
In winter the marshy plains abound with wild-fowl, ducks, geese, and water-birds of varied kinds; but of the winter season in the marisma, its fowl and fowlers, we treat fully hereafter.
The spring-months abound in interest to the naturalist. Imagination can hardly picture, nor Nature provide, a region more congenial to the tastes of wild aquatic birds than these huge marismas, with their silent stretches of marsh-land and savannahs, cane-brake and stagnant waters, and their profusion of plant and insect life. Here, in spring, in an ornithological Eden, one sees almost daily new bird-forms. During the vernal migration the still air resounds with unknown notes, and many of those species which at home are the rarest—hardly known save in books or museums—are here the most conspicuous, filling the desolate landscape with life and animation. The months of February and March witness the withdrawal of most of the winter wild-fowl. Day after day the clouds of Pintails and Wigeon, of Shovellers, Pochards, and Teal, and fresh files of grey geese wing their way northwards; while their places are simultaneously being filled by arrivals from the south. April brings an influx of graceful forms and many sub-tropical species, for which Andalucia forms, roughly speaking, the northern limit; while in May is superadded a "through transit," which renders the bird-life of that period at times almost bewildering.
But before attempting to fill in the details, it is necessary to explain the mode of travel and the methods by which these wildernesses can be investigated. Uninhabited and abandoned to wild-fowl and flamingoes, and lying remote from any "base of operations," the exploration of the marismas is an undertaking of some difficulty. They cannot, owing to their extent, be worked from any single base; hence, thoroughly to explore them and penetrate their lonely expanses, necessitates a well-equipped expedition, independent of external aid, and prepared to encamp night after night among the tamarisks or samphire on bleak islet or barren arenal. Some of our earlier efforts, twenty years ago, resulted in total failure. Setting out by way of the river, the light launches suitable for the shallow marisma proved unequal to the voyage up the broad Guadalquivir; while, on the other hand, the larger craft in which that exposed estuary could be safely navigated were useless in the shallows. One attempt was frustrated by sunstroke; on another our Spanish crew "struck" through stress of weather, leaving us at a lonely spot some thirty miles beyond Bonanza with no alternative but to submit, or go on alone. We had, however, some reward for this enforced tramp in discovering the Dunlin (Tringa alpina) nesting at a point over a thousand miles south of any previous record of its breeding-range. Finally, we chartered at San Lucar a large fishing-yawl, bound up-river, and after a long day in that malodorous craft, beating up against wind and stream, and with our three punts in tow, we at length succeeded in launching them on the waters of the middle marismas.
The geese and wigeon had entirely disappeared—this was early in April—but passage-ducks still skimmed in large flights over the open waters. These were chiefly Mallards, with Pintails and Pochards (both species), a few Teal, Garganey, and probably other species. We also shot Shovellers out of small "bunches," and among the deep sluices of some abandoned salt-pans (salinas), where we spent the first night, three or four Tufted Ducks, and a pair of Pochards. I killed a single Scoter drake as late as April 13th, and was shown as a curiosity a Cormorant which had been killed by some fishermen on the river a day or two before.
One cannot go far into the marisma without seeing that extraordinary fowl, the Flamingo, certainly the most characteristic denizen of the wilderness. In herds of 300 to 500, several of which are often in sight at once, they stand like regiments, feeding in the open water, all heads under, greedily tearing up the grasses and water-plants that grow beneath the surface. On approaching them, which can only be done by extreme caution, their silence is first broken by the sentries, which commence walking away with low croaks: then the whole five hundred necks rise at once to full stretch, every bird gaggling his loudest as they walk obliquely away, looking back over their shoulders as though to take stock of the extent of the danger. Shoving the punt a few yards forward, up they all rise, and a more beautiful sight cannot be imagined than the simultaneous spreading of their thousand crimson wings, flashing against the sky like a gleam of rosy light. Then one descends to the practical, and a volley of slugs cuts a lane through their phalanx.
In many respects these birds bear a strong resemblance to geese. Like the latter, Flamingoes feed by day: and quantities of grass, etc., are always floating about the muddy water at the spot where a herd has been feeding. Their cry is almost indistinguishable from the gaggling of geese, and they fly in the same chain-like formations. The irides of the oldest individuals are very pale lemon-yellow: the bare skin between the bill and the eye is also yellow, and the whole plumage beautifully suffused with warm pink. In the young birds of one year (which do not breed) this pink shade is entirely absent, and even their wings bear but slight traces of it. The secondaries and tertiaries of these immature birds are barred irregularly with black spots, and their legs, bills and eyes are of a dull lead colour. In size flamingoes vary greatly: the largest we have measured was fully six feet five inches—there are some quite seven feet—while others (old red birds) barely reached five feet.
The further we advanced into the marisma the more abundant became the bird-life. Besides ducks and flamingoes, troops of long-legged Stilts in places whitened the waters, and chattering bands of Avocets swept over the marshy islets: around these also gyrated clouds of Dunlins in full breeding-plumage: smaller flights, composed of Kentish plovers and Lesser Ring-dotterel mixed, with Redshanks and Peewits: the two latter paired. One morning at daybreak, a pack of two hundred Black-tailed Godwits pitched on an islet hard by our camp, probably tired with a long migratory journey, for these wary birds allowed two punts to run almost "aboard them," and received a raking broadside at thirty yards.[19] On April 11th we obtained a single Grey Phalarope (Phalaropus fulicarius), swimming like a little duck on an open arroyo, and the Sanderling, Green and Common Sandpipers, were all abundant, together with Ruffs and Reeves, though in mid-April the former still lacked the full nuptial dress. Greenshanks and Knots we did not meet with then; though a month later (in May) swarms of both these species, together with Whimbrels, Grey Plovers, and Curlew-Sandpipers, all in perfect summer plumage, poured into the marisma, to rest and recruit on their direct transit from Africa to the Arctic.