THE BOOM OF THE BITTERN
By ANTHONY BUXTON IHAVE been asked on a raw wet day in March to write something " springish " connected with birds. There is, and there has been for some time, a Missel Thrush bravely contending with the elements and pouring out his no doubt excellent but rather boring song. Song Thrushes are doing the same to better pm-pose, Robins and Hedgesparrows are chiming in, but anybody can hear them for themselves all over the country.
It seems to me more appropriate to talk of a mysterious bird not so accessible to the public, which even at 700 yards can make himself audible in a house with every door and window closed. No human being would be likely to give the name of song to the sound he produces, but to the cock Bittern, who makes it, and to his hen, it is presumably the song of songs. Despite its quality of resonance and penetration it is not really a loud noise, even at a distance of ten yards, and it is always difficult to be certain how far off its author is. A Bittern's boom is more like a young fog-horn than anything else, but it has also been mistaken for a surly bull. Starting with some practice grunts in February, tuning up in March, and in full force in April and May, the boom peters out just after the young are hatched. Despite constant attempts, I have never yet succeeded in seeing a Bittern in the act of " booming." The bird is a skulker and sticks to the thickest reed beds, where nothing can be seen five yards ahead, and where a noiseless approach is practically impossible.
I have been within five yards of a " boomer " and when at really close range three totally distinct sounds are always audible. First there is a sort of warning—a double tap or click made apparently by the grating of two hard surfaces, possibly caused by a double click of the bill or a sudden stiffening of the primaries after the manner of a turkey cock. After a little silence this warning is followed by the intake of air—producing much the same sound as a man makes just after his wind has been violently taken. This intake can be heard at about fifty yards on a still day; it is repeated several times and is followed by a series of blasts, or " oomps," repeated from two to six times. These blasts which constitute the boom proper are the sounds which can penetrate a closed house.
A Bittern nearly always looks ridiculous whatever it is doing, and its appearance whilst producing these three sounds is, I doubt not, weird in the extreme. Unfortunately although a cock Bittern has a very distinct booming area, which seems to bear little or no relation to the locality of the nest, he wanders about constantly in that area during his vocal periods. The booms are made as a rule from very thick covert, but not always, for I almost caught a Bittern performing last year on bare ground from which reeds had just been cut. A slow approach was made through standing reeds to a point which seemed to be within about twenty yards of the bird. Then apparently the bird heard something, for there was dead silence for half an hour, while I stood motionless. At last I gave it up and moved forward across an open space, when the bird rose from my feet, and all round the spot were freshly made oval hollows filled with water into which his body had clearly been depressed, probably in the act of booming. If I had succeeded in advancing a few more yards without detection the whole performance would have been visible.
Bitterns boom both by day and night and are partic- ularly vocal on a warm still evening. During the day time a spell of sunshine after cloud generally stirs them into song, but the most certain incentive of all is the sight of another Bittern, probably a hen, flying over their head. At such time I have heard even a 'boomer, who had just been reduced to silence by disturbance, go into a frenzy of hurriedly produced " oomps." From a hide situated at seven feet from a Bittern's nest, I have seen the effect of the cock's boom on the hen. She crouched flat and pointed her beak to the sky, with a look of intense concentration in her eye. She was clearly " moved " and indeed " transfixed," but whether with horror or admiration it was impossible to say. One Easter a Bittein had settled near a dyke where sailing boats were moored for the night ; gramophones were in full swing, plates were being washed up and banged about, laughter and conversation were general, and in the midst of all the noise of humanity on holiday there sounded at regular intervals boom upon boom from the centre of the reed-bed not thirty yards from the crowd.
A Bittern has a firm belief in its own invisibility, once it has assumed its "freezing" attitude, with elongated neck and nose pointed to the sky, and indeed the brown stripes on its plumage do closely resemble the reed stems surrounding it. On one occasion my miller found himself standing by the side of a Bittern in the middle of a reed- bed, and informed a companion of the fact. The latter ran to a boat, rowed home for a camera, returned in forty minutes to find the miller and the Bittern still standing side by side. During his absence the Bittern had once shown signs of desiring to depart, but the miller had stamped his foot in protest and the bird had at once desisted from any attempt to move.
In 1911, after 43 years of absence as a breeding species from the Broads, a pair of Bitterns are known to have nested in Norfolk. Since that date the increase has been amazing, and last year seven cock Bitterns were-heard from one spot booming simultaneously. Indeed it is probable that the birds are already finding that there are too many beaks for comfort engaged in eel-fishing on the waters of the Broads. If they have not done so already, the surplus anglers will soon be spreading to other parts of these islands, in reach of fresh reed-beds and less crowded waters whereon to ply their favourite sport.
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