Chorthippus Chorthippus albomarginatus

Calling song (Figs 22–23, 28–29) The calling song of Ch. albomarginatus lasts for about 0.45–0.65 s. As a rule, a male produces 3–4, rarely up to 8 calling songs separated by intervals of 2–3 s. In albomarginatus , the legs vibrate synchro- nously in the very beginning of the calling song, whereas during the main part of the song, they move alternately, each leg at a rate of about 40/s. All the leg movements of the main part of the calling song are regular and of about equal amplitude. The sound pulses are produced during either up and down leg movements. Thus, the sound pulses follow rather regularly at a rate of about 70–80/s, separating by distinct gaps. Quite often, one loud pulse produced in the beginning of the song is separated from the following pulses. The calling song of albomarginatus may be distinguished from the song of all other spe- cies of this group by the lower pulse rate and the presence of distinct gaps between pulses.

Courtship song (Figs 50–55, App. 2) Among all European species of the group, Ch. albomarginatus produces the simplest song regarding the number of the song elements and other features of the courtship behaviour. The courtship song of albomarginatus starts with an alternation of two elements, the A and B elements. The A elements are produced with legs vibrating rapidly (at 52–54/s) in a high position, the B elements are produced with legs held in a lower position and vibrating much more slowly (at 20–22/s). The A and B elements contain the pulses repeated at a rate of the corresponding leg vibration. About 15–30 s after the beginning of the courtship, a third C element appears. The last B ele- ment (B1), preceding the C element, has always a pause at about half of its duration. The element C is produced while the legs are in an extra-high position vibrating in a complex pattern: the low-amplitude vibrations alternate with the high-amplitude ones. Element C contains three-throw pulses; each middle pulse is often louder than the other two. In the very beginning of the C element, one louder and longer pulse is produced, called the C1 element. After the end of the C element, the A and B elements alter- nate again. In a fully developed courtship, each C element follows after 3–7 pairs of A/B elements. During A and B elements, the two legs are moved synchronously. In the very beginning of the C ele- ment, the legs are moved synchronously as well, but in the main part of the C element, the legs are moved alternately. In the beginning of courtship, A and B elements are almost of the same loudness (Helversen 1986), however, in the fully developed courtship, A elements are louder than B elements. There is some geographical variability in the number of A/B pairs between C elements and in the degree of the loudness increase of A elements during each cycle (compare Figs 50–52). Relative loudness of pulses in the C element slightly varies as well. [1]

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