A Survey of Bath's Bats

In 2016, Bath & North East Somerset council commissioned Clarkson and Woods Ltd to carry out a survey of bats along the river Avon.
During the survey, observations of bat calls were collected from 10 sites along the River Avon around Bath. The recordings of bat calls were automatically classified into different species based on characteristics of the sounds. In addition to the automated classifications, some manual classifications were also carried out.
The data from the survey has been published as open data in our data store. This story summarises some of the data.
The map below shows the locations from which the observations were collected.

Bat Species

The survey identified 16 different species of Bath living near the river in 2016.
The table on the right list includes the names of all of the species and the codes used to refer to them in the datasets.
Some observations were not classified as Bats. These are marked as "Not identified", "Not applicable", or "Not a bat"!
Soprano Pipistrelle
Greater horseshoe bat

Number of observations by species

Counting the number of observations by species, we find that the Soprano pipistrelle (coded as PIPY) was most frequently recorded.
The next most common was the Common pipistrelle.
The rarest bat was the the Greater horseshoe (coded as RHFE). This bat is only found in the south west of England.

Which is our rarest bat?

But the numbers of observations just tell us how often the bats were heard along the river. They don't tell us how rare those bats are across the country.
With a bit of detective work you could use the data above to figure out which of the bats are the rarest.
This article from the BBC lists seven of the UK's rarest bats. It might help get you started.
The moon is low tonight, by Perry Harris