CHAPTER XXXVIII

THE "CORROS," OR MASSING OF WILDFOWL IN SPRING FOR THEIR NORTHERN MIGRATION

The withdrawal of the wildfowl at the vernal equinox affords an unequalled scenic display. It forms, moreover, one of those rare revelations of her inner working that Nature but seldom allows to man. Her operations, as a rule, are essentially secretive. A little may be revealed, the bulk must be inferred. Here, for once, a vast revolution is performed in open daylight, _coram populo_--that is, if the authors and a handful of Spanish fowlers be accepted as representative, since no other witness is present at these scenes enacted in remote watery wilderness.

Up to mid-February the daily life of the marisma continues as already described. From that date a new movement becomes perceptible--the seasonal redistribution. Daily there withdraw northward bands and detachments counting into thousands apiece. But no vacancy occurs since their places are simultaneously filled by corresponding arrivals from beyond the Mediterranean.

It is at this precise epoch that there occurs the phenomenon of which we have spoken.

Towards the close of February, dependent on the moon, a marked climatic change takes place. A period of sudden heat usually sets in--a sequence of warm sunny days, breathless, and at noontide almost suffocating. But each afternoon with flowing tide there arises from the sea a S. W. breeze, gentle at first and uncertain but gaining strength with the rising flood.

Already, shortly before this change, the duck-tribes had partially relaxed their full mid-winter activities--owing to abundant spring growths of food-plants, had become more sedentary; if not sluggish, at least reluctant to move. After the brief morning-flight not a wing stirred. But now, scan the mirror-like surface of some great _lucio_ and you will recognise a new movement distinct and dissimilar from regular hibernal habit. There float within sight (and the same is happening at a score of places beyond sight) not only the usual loose flotillas, but three, four, or five concrete assemblages of densely massed fowl whose appearance the slightest scrutiny will differentiate from the others. These are not sitting quiescent. The binoculars disclose a scene of perpetual motion, well-nigh of riot--one might be regarding a feathered faction-fight. Hundreds of units fight, splash, and chase, or throw up water with beating wings till surf and spray half conceals the seething crowd. That flicker of pinions and flying foam are, moreover, accompanied by a chorus of myriad notes--a babel of twirling sound blended in rising and falling cadences, comparable only to the distant roar of some mighty city. A more singular spectacle we have not encountered.

Inquiry from one's companion elicits the reply that these assemblages are _hechando corros para irse_ (literally, "forming choruses preparatory to departure")--an expression which conveyed no more significance to us than it can to the reader.[64] We decided to return at daybreak to see this thing through, and after watching the phenomenon a score of times can now explain it.

During the morning hours there are established focal points whereat assemble those units already affected by the emigrant furor. These (at first, perhaps, but a score or two) rapidly increase in numbers till each focus becomes the nucleus of a corro. The seasonal infection spreads, and as its influence impregnates the surrounding masses, these, singly or in scores or hundreds as the passion seizes them, hasten to join one or other of the mobilising army-corps. Within an hour or two the insignificant original nucleus has developed into a vast host all in a ferment of agitation, and being constantly reinforced by buzzing swarms of recruits from without.

All this procedure, remember, has been taking place during the blazing noontide heat. Now the hour is 2 P.M., and the first gentle breath of the daily sea-breeze--the _viento de la mar_--is becoming perceptible. This breeze springs from the S. W., and let us here admit that, being fowlers as well as naturalists, our observance of the phenomenon has usually been carried out upon a _lucio_ which happens to terminate towards the N. E. in a long narrow bight fringed by tall reeds and bulrush, where, concealed in friendly covert, we can continue the observation while glancing along the barrel of a punt-gun. That secondary fact is merely incidental and, it so happens, facilitates the main object.

A mile to windward three such armies are mobilising separately within the scope of our view; and now the gentle force of that sea-breeze begins to impel those unconscious hosts, too preoccupied with all-absorbing passion to notice detail, directly towards the point whereat we lie concealed.

By this time the sun has three or four hours of declension and the thin dark line representing thousands of surging atoms has drifted down to within 200 yards. We can study at short range an amazing phenomenon. In weird exuberance they fight and flirt, chase, cherish, and flap till churned water flies in foam and a discordant roar of sibilant sound fills to the zenith the voids of space. The volume of voices defies description since these assembling multitudes belong to no single species, but include a promiscuous agglomeration of all that care to enlist, and each adds its own distinctive element to the general uproar.[65] Around the floating host new-comers buzz like swarming bees, each seeking some spot to wedge itself into the crowd.

To-night the main _corro_ that we had been awaiting drifted past our front a trifle beyond effective range. The two that followed both "took the ground" and remained stationary, away to the right. The chance of making a great shot had failed; but we were content to watch the phenomenon to its finish.

Now the sun dips. The western sky is filled with golden glory; in twenty short minutes darkness will have enveloped the earth. Then in a moment, as by word of command, silence, sudden and impressive, reigns where just before that torrential babel had raged. Such, now, is the stilly silence that by comparison the pipe of a passing redshank sounds well-nigh scandalous! A few seconds pass. Then, dominated by a single impulse, the concentrated mass on our front rises simultaneously on wing. The spell of silence is broken; the roar of pinions reverberates far and wide. They're off--bound for Siberia!

Yet unperplexed as though one spirit swayed Their indefatigable flight.

Holding the same massed formation, the fowl in three or four broadening circles quickly attain a considerable altitude--say 100 yards--and then head away on their course, _ALWAYS_ (so far as they remain visible) to the _SOUTH-EAST_--diametrically opposite to the direction one would expect. As in deepening darkness we set forth on our homeward voyage, the heaven above pulsates at intervals with the beating of wings as yet more north-bound _corros_ pass overhead.

Certain notable facts are observable in this vernal exodus. For upwards of twelve hours prior to departure the outgoing fowl take no food. That period is devoted exclusively to preparation and overhaul, _and_ to pairing. Plumage is preened and dressed till each unit is spick and span, speckless, and not a feather misplaced. All, moreover, are absolutely empty--in best and lightest travelling trim.

When ducks are _acorrados_--that is, formed into _corros_ (the term is used thus in verb-form)--their normal watchfulness is relaxed. All thought and energy are concentrated on the impending event. Hence, at these periods they are apt to fall an easier prey to the fowler and on wholesale lines. The native gunners with their trained _cabresto_-ponies sometimes unite and enormous totals are secured as the result of a single joint broadside. The fowl thus obtained afford proof of the facts just stated, being all absolutely empty; besides which many different species will be killed at the one shot.[66] These men also state that the ducks start already paired and flying side by side; this, they say, explains the ferment and commotion of the previous hours--courting and sorting. Adult ducks, as previously indicated (p. 110), apparently pair for life; but since some species (such as wigeon) take at least two years to gain maturity, it is probable that the sexual phenomena which are so conspicuous in the _corros_ represent the first pairing of the newly adult two-year-olds.

The most favourable time for the assembling of corros is on those days when great heat and calm at midday is succeeded towards evening by an extra strong sea-breeze. On such occasions very large numbers will leave between sundown and dark. Northerly winds will almost absolutely arrest the exodus.

For the season of 1900-1901 our game-books showed a total of 4849 wildfowl (4674 ducks and 175 geese)--a record for which we were good-humouredly taken to task by our venerable friend the late Canon Tristram, who thought it looked excessive. The figures certainly are big, but the next entry in the book reads:--

_March 15._--This evening between fifty and seventy _corros_ left within half an hour--say 50,000 to 70,000 ducks. Next morning the marisma appeared as full as ever.

Our toll of 5000 seemed by comparison but as a drop in the bucket!