Effects of nocturnal celestial illumination on high-flying migrant insects
Data files
Apr 15, 2024 version files 274.24 KB
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analysis_of_heading_r-value.xlsx
112.47 KB
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analysis_of_height_vs_variables.xlsx
58.20 KB
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analysis_of_number_vs_variables.xlsx
100.32 KB
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README.md
3.26 KB
Abstract
Radar networks hold great promise for monitoring population trends of migrating insects. However, it is important to elucidate the nature of responses to environmental cues. We use data from a mini-network of vertical-looking entomological radars in the southern UK to investigate changes in nightly abundance, flight altitude, and behaviour of insect migrants, in relation to meteorological and celestial conditions. An abundance of migrants showed positive relationships with air temperature, indicating that this is the single most important variable influencing the decision to initiate migration. In addition, there was a small but significant effect of moonlight illumination, with more insects migrating on full moon nights. While the effect of nocturnal illumination levels on abundance was relatively minor, there was a stronger effect on the insects’ ability to orientate close to downwind: flight headings were more tightly clustered on nights when the moon was bright and when cloud cover was sparse. This indicates that nocturnal illumination is important for the navigational mechanisms used by nocturnal insect migrants. Further, our results clearly show that environmental conditions such as air temperature and light levels must be considered if long-term radar datasets are to be used to assess the changing population trends of migrants.
https://doi.org/10.5061/dryad.sn02v6xb5
Description of the data and file structure
In our research, we use data from a mini-network of vertical-looking entomological radars in the southern UK to investigate changes in nightly abundance, flight altitude, and behaviour of insect migrants in relation to the celestial conditions. This upload database contains three data files involved in the study; each data file corresponds to a section of the analysis, including the impact of the moonlight illumination on the number, flying height, and headings of the large and small migratory insects.
Dataset1: analysis of number vs variables.csv
It contains four sheets:
‘large_spring’: the related number analysis parameters for large insects in spring
‘large_autumn’: the related number analysis parameters for large insects in autumn
‘med_spring’: the related number analysis parameters for medium insects in spring
‘med_autumn’: the related number analysis parameters for medium insects in autumn
X: The radar site name and sampling date
number: the number of large or medium insects in each day over a radar site
temp: ground-level temperature
moon illumination percentage: percentage moon illumination (%)
moon rise_hr: the hour of moon rising time
season: sampling migratory season spring or autumn
Dataset2: analysis of heading vs variables.csv
It contains four sheets:
‘large_spring’: the related orientation analysis parameters for large insects in spring
‘large_autumn’: the related orientation analysis parameters for large insects in autumn
‘med_spring’: the related orientation analysis parameters for medium insects in spring
‘med_autumn’: the related orientation analysis parameters for medium insects in autumn
X: The radar site name and sampling date
number: the number of large or medium insects in each migration event over a radar site
r.BA: the r value from the Rayleigh test for insect headings in each migration event which show common orientation
p.BA: the p value from the Rayleigh test for insect headings in each migration event which show common orientation
mean.BA: the mean value(degree) of the insect headings in each migration event which show common orientation, 0 is north, 180 is south
moon illumination percentage: percentage moon illumination (%)
moon rise_hr: the hour of moon rising time
cloudcover rate: the cloud cover rate(%)
season: sampling migratory season spring or autumn
Dataset3: analysis of height vs variables.csv
It contains four sheets:
‘large_spring’: the related flying altitude analysis parameters for large insects in spring
‘large_autumn’: the related flying altitude analysis parameters for large insects in autumn
‘med_spring’: the related flying altitude parameters for medium insects in spring
‘med_autumn’: the related flying altitude parameters for medium insects in autumn
number: the number of large or medium insects in each migration event over a radar site
moon illumination percentage: percentage moon illumination (%)
cloudcover rate: the cloud cover rate(%)
season: sampling migratory season spring or autumn
Two vertical-looking insect radars (VLRs) located at three sites in southern England between 2000 and 2009 collected insect abundance and flight behaviour data. One VLR was located at Rothamsted Research, Harpenden, Hertfordshire, for the whole 10-year period. The other VLR was at Malvern, Worcestershire, from 2000 to 2003 and then at Chilbolton, Hampshire, from 2004 to 2009. All statistical analyses were conducted in the R software environment (version 3.6.3).