Data summary – 1
The following animation shows bat activity for each survey site over time. The size and colour of each bubble represents the number of bat passes in each five minute period with the time of each recorder normalised to ‘time after sunset’ (displayed in the top-left of the video).
Notes
- All the recordings for a particular site/survey are aggregated together so effectively what you will see is an average across the week.
- The data includes all species grouped as Common Pipistrelles, Soprano Pipistrelles and ‘others’ so you may see multiple bubbles at the same location at the same time.
- Some sites had surveys completed multiple times, again you may see multiple bubbles for the same location.
Data Summary – V2
The issue with the animation above is that although it aligns to sunset to show emergence, it will distort the view of returning bats before sunrise because the days are differing lengths. This can be seen in the following histograms:
Bat detection time data aligned relative to sunset (showing emergence behaviour):
Bat detection time data aligned relative to sunrise (showing returning behaviour):
The first graph shows a more accurate view of bat emergence, whereas the second graph gives a more accurate view of bats returning. This is because the bat behaviour will correspond to sunset/sunrise and the survey data has been recorded over multiple nights of differing duration.
To try to account for this, the following animation splits the survey data in two halves. It first counts up in intervals ‘after sunset’, and at 4:30 (four and a half hours after sunset) switches to count down in intervals ‘before sunrise’. There will be some inconsistencies in the middle (duplication), but should better show both emergence and returning behaviours.
Recorded Data
Common Pipistrelle Passes by Street
The following histograms show the number of recorded bat passes aggregated by street in each five minute interval. They are all normalised to be relative to sunset. Note: these have been recorded over different weeks, so are not directly comparable but do give an idea of the level of activity in a specific area.
Soprano Pipistrelle Passes by Street
The following histograms of Soprano Pipistrelles generally show a small number of sporadic passes with a couple of exceptions. The most notable of these is Fryth Mead which clearly has a population roosting close by.
