AudioMoth metadata in R

 The latest release (0.0.4) of SonicScrewdriveR is now on CRAN and includes two new functions for reading metadata from AudioMoth devices. 

audiomoth_config() parses the CONFIG.TXT written to the microSD card during device operation.

audiomoth_wave() parses the metadata written in the Comments field of the wave file metadata. This allows easy access to time, date, temperature (if supported by firmware) and other metadata as an R list.

Please raise GitHub requests with any issues (or even requests).

Bioacoustics and military history

My Bioacoustics and military history blog post on BioAcoustica.

Audubon Core Updates: Public Review of Proposals to Update Existing Standards

The Audubon Core Maintenance Group is advancing six proposals to update terms in the Audubon Core. A 30 day period for public comment is now open. It closes at the end of September. Three of the proposals create controlled vocabularies that were envisioned during the initial formulation of the Audubon Core, but were incomplete when the vocabulary was ratified. Three proposals are for adding new terms to Audubon Core that are important for biodiversity sound descriptions (i.e., metadata for biodiversity sound files).  To view the proposals, visit https://github.com/tdwg/ac/milestone/2 and view the individual proposal issues and their associated documents. To comment on the proposals, leave comments on the relevant proposal issue. If you are unable to create GitHub comments, send them to the Maintenance Group convener at steve.baskauf@vanderbilt.edu .

Generating a swept sine wave in R

This uses functionality from the sonicscrewdriveR package:

install.packages("devtools")

library(devtools)

install_github("edwbaker/sonicscrewdriver")

library(sonicscrewdriver)

Generate a Wave object with a sine sweep from 0 Hz to 1kHz over two seconds:

w <- sweptsine(f0=0,f1=1000, sweep.time=2, output="wave")

So good they named it once

Oecanthus pellucens (Scopoli, 1763) - the Italian tree cricket - was recently found breeding in Dungeness, Kent, UK (Sutton, Beckmann & Nelson, 2017).

There are a number of recordings of this species in the BioAcoustica repository: recordings of Oecanthus pelluscens on BioAcoustica.

Like many tree crickets it has a certain translucent quality, and it is this that Giovanni Antonio Scopoli alludes to when giving it the specific name pellucens. Torre-Bueno's A Glossary of Entomology gives the definition:

pellucid, pellucidity, pellucid, transparent, whether clear or coloured.

(This definition is somewhat incorrect, something transparent is clear, it can be coloured or colourless, but I digress)

 That Scopoli refers to this property is clear in the original description: "Caput album, subpellucens". Subpellucens is best translated as opaque.

All very well, but so far not particularly interesting. The (minor for most) interest comes from an alternative definition of pellucid, here borrowed form the Oxford English Dictionary.

Of music or other sound: clear and pure in tone.

Crickets in general are known for their pure bell like songs, and that of Oecanthus pelluscens is no exception. Shown below are three chirps from the recording above (time on x-axis, frequency on y-axis). This shows a strong resonance frequency, with three clear, regularly spaced, harmonics: a clear and relatively pure tone indeed.

Oecanthus pelluscens, a cricket so clear and pure it could be named just once.

Orthoptera Culture Group

Google Group for discussing the lab/zoo Culture of Orthoptera (grasshoppers/crickets/bush-crickets).

Churr-worms, Eve-churrs & Mole crickets

Churr-worms, eve-churrs and mole crickets are (of course) all the same creature:

"Few country people today are acquainted with the Mole Cricket, but formerly, when presumably it was commoner, it went by such names as "Churr-worm" and "Eve-churr". These concern its strange jarring "note" which is heard chiefly during the evening in the spring." 

- G. E. Hyde. (1961) Teach Yourself Entomology. The English Universities Press Ltd, London.

But what is a churr? The Oxford English Dictionary (OED) describes it as "expressive of a somewhat deeper and hoarser sound than chirr", and chirr as "to make the trilled sound characteristic of grasshoppers, etc."

The Mole Cricket (in this case Gryllotalpa gryllotalpa - there are many others outside the UK) produces its churr in the evenings and nights, so Eve-churr seems appropriate. This vernacular name is shared, however, with the nightjar (Caprimulgus europaeus). As the name seems obsolete for both species the chances for confusion are currently minimal. Nightchurr is also an obsolete (regional) name for both these species (OED).

The OED also distinguishes a chirr from a chirp, the chirr being "often nearly equivalent to chirp , but properly expressing a more continuous and monotonous sound." As a side-note many authors in bioacoustics have followed Broughton (1976) in using the precisely defined neologism echeme in place of chirp.

There are no doubt other regional names for the Mole Cricket in the UK, John George Wood in his 1866 book Homes without hands: being a description of the habitations of animals, classed according to their principle of construction gives the delightful Croaker.

The status of the Mole Cricket in the UK has not improved and it is confined to the New Forest. Until recently the only confirmed recent record was several sound recordings, one of which is below.