Stridulators

August is a quieter month for birdsong but there are still plenty of subjects for the enthusiastic sound recordist. For example, Roe deer are rutting this month and all the stridulating Orthoptera have attained their adult stage.

Undoubtedly, the best way to treat these insects is to capture them and record in the controlled conditions of a bio-acoustical laboratory and that is how the commercial sound guides were produced. If this sounds like too much trouble, it is quite feasible to record the calling songs in the field.

The grasshoppers are diurnal and stridulate best in sunshine. They are terrestrial and easy to locate.

Obviously, they will go quiet if you cover them with a shadow, but the polycarbonate reflector on a Telinga is transparent. Remove the dark wind cover and hover over the target using headphones. The transparent material acts as a greenhouse and the insects quickly respond as the sun warms them.

A good tip is to carry a pair of scissors and trim any projecting stems that inevitable cause handling noise.

It is easy enough to record and learn the calling songs of the local species; ideal for basic survey work and simple pleasure.

My short clips were recorded in this way although mp3 compression has compromised the quality.

Listen here to Corthippus brunneus, our Common Field Grasshopper. This species is gregarious and males ‘chirp’ in chorus. Hence, the French call it le criquet duettiste.

      Chorthippus brunneus

The bush-crickets are slightly different, many are crepusclar and nocturnal. However, advertising males are easy to locate and you can use a bat detector if you suffer from presbycusis. They keep still when stridulating and it is easy to maintain a steady level by ‘close miking’.

My tip is to increase your sampling rate to 96 kHz to accommodate their higher frequencies which may extend into the ultrasonic range.

Here then is a Short-winged Conehead, recorded this month in the field. This bush-cricket is both diurnal and terrestrial, which is not typical. Its characteristic output is recognisable by the regular change of pace as it slows down to a ticking rate before speeding up again. 

      Conocephalus dorsalis

Good hunting.

Prolix

Leave a Reply