The Grasshopper Warbler in North Worcestershire
THE GRASSHOPPER-WARBLER (LOCUSTELLA
NÆVIA) IN NORTH WORCESTERSHIRE.
By H. Eliot Howard.
Very few birds interest me as much, I might almost say none more, than the Grasshopper-Warbler, and the following notes are the result of many years' observation in this county. Probably, owing to the habits of birds varying so widely in different districts, these notes will not be found to agree entirely with the experiences of other naturalists who have studied this Warbler in different parts of the British Islands to myself.
The dates of arrival in this county for the last four years (leaving out 1898, when I was absent) are as follows: 1896, April 19th; 1897, April 23rd; 1899, April 20th; 1900, April 19th. It is certainly much more regular in its time of arrival than the other summer migrants, the dates, as will be seen, varying very little. No matter what the weather is when it first arrives, its note is sure to be heard in the morning—cold, frost, or rain seeming to have very little effect in preventing it singing. As a rule, they will be found at once in the spot where they intend to breed, but I have sometimes found them for the first few mornings after they arrive in hedges by the side of a road. One which I especially noticed last year was singing in a hedge which was absolutely bare, and opposite to which was a farmyard; but they all pass on in a day or two to more suitable breeding haunts.
There are certain places where I can always be sure of finding one or two pairs, and these are for the most part osier-beds which have been cut down two or three years previously. The osiers are then about four feet high, intermingled with hazel, and with very thick undergrowth. These sort of places they seem to prefer for breeding purposes more than any other; but I have found them fairly plentiful in large woods, where the undergrowth is very thick, but in almost every instance there has been water somewhere near. A few breed in thick hedges, and it was in one of these that I found the only pair breeding away from water of some kind that I have ever found. This was in 1897, when a pair bred in a thick hedge next to a field of corn. They are plentiful enough in this county—you might almost call them common—but, on account of their shy and retiring habits, they are little known and easily passed over.
In the number of arrivals there is great variation—more, I think, than with any of the other migrants; and, if they are plentiful one year, and the young are successfully reared. I have as often as not found that they come in exceptionally few numbers the next year. The year 1897 I remember well, as they visited us in greater numbers than usual. In one osier-bed, about a quarter of a mile long, I found six different pairs; the next year, in the same osier-bed, only one pair, although the conditions appeared to be just the same. In order to see the Grasshopper-Warbler at its best you must watch it for the first few hours after dawn—and indeed this may be said of all birds during the summer months; but at no time is Locustella nævia so lively as during the first two hours of daylight, and at no time of the year is it so amusing as during the last week in April and the first week in May. It is then that the females arrive, and they begin to mate. It will repay anyone to sit still for an hour or two at dawn to watch them. The female then walks along amongst the undergrowth, threading her way in and out, sometimes pecking or pretending to peck at something; the male follows a few feet behind, at times picking up a dead leaf in his bill, and carrying it for some distance while following the female, apparently with no object, unless it is a gentle reminder to her that he wishes to commence nesting operations. These operations are generally disturbed by the appearance of another male on the scene, and at once they set to and chase one another, now and then in their excitement settling on a bush and singing for a few seconds; the flight when this goes on is, as a rule, very rapid, and it is not long before he returns to the female and again commences to walk after her, varying the operation at times by crawling up to the top of a bush and commencing to sing.
Directly they are paired they commence nesting operations, the male at this time singing a great deal in the mornings, sometimeson the top of a bush, sometimes low down. When the sun first rises they are fond of sitting on dead branches in order to preen their feathers. If when at the top of a bush he happens to see you, he dives down into the middle and disappears immediately, only to reappear presently, if there is nothing to alarm him, crawling up the middle of the bush and walking along the branches until he gets back to his original perch, when he will again commence to sing. The habit they have of crawling up the bushes is so like that of a Field-Mouse, that I have more than once mistaken the one for the other, the Field-Mouse also being very fond of creeping up the stem of bushes.
The female seems to be more fond of walking along the ground than the male, and when disturbed off her nest slips quietly down amongst the thick undergrowth that generally surrounds the nest, shortly to return providing there is no noise or movement to frighten her.
I have never heard the female utter a note of any kind, though I have many times watched both when mating, and when the young were hatched. She is more difficult to watch than the male, on account of her habit of creeping along the ground; in fact, the only times I have seen the females at all lively is for the first hour after dawn during May and June. At that time the male and female chase one another, and I have seen the female when tired of this sitting quietly on a dead branch of a nut bush, but by sunrise she was off back to her nest. The male in this county sings at most hours of the day and night until the female begins to sit, when he is almost silent, and remains so till the young are out of the nest, then he commences to sing again—that is to say, from the middle of May till about the third week in June.
This habit is curious—in no other bird have I noticed it—and I should be interested to know if others have observed the same thing. I said almost silent, because I once heard one singing very quietly on a hot afternoon early in June. From the time he arrives till the middle of May he sings continuously in the morning, and certainly at times he is very hard to locate, owing to his note sounding farther off than it really is, and vice versâ, the result of a habit he has of turning his head from side to side when singing. He is also fond of singing at night; but I cannot say I have ever heard him in the middle of the day, although I have early in the afternoon.
The nests I have found are few, and I remember the first one was by consequence of luck—or rather ill-luck—for I trod on it. It was in the middle of some bent, practically on the ground, and this is the spot they seem to be most fond of for breeding purposes. One very pretty nest I came across about three years ago was between two and three feet from the ground, amongst a lot of long dead grass; the nest itself was built entirely of the same grass, but this is the only one I have found so far off the ground.
The young leave the nest soon after they are hatched. Whether or not two broods are reared here in the year I cannot say, never having found a second one; but the old birds sing during most of July, so probably, in some cases, two broods are reared.
The earliest date at which I have found the young hatched is June 6th, but that was exceptional. In September the young males make an attempt at singing, but it only results in a curious crackling noise; they are certainly more easily approached than the old birds, and at this time of the year I have often seen them basking in the sun on dead branches, when they will allow a very near approach before disappearing into the bushes with that curious habit they possess of flirting their tail.