The most remarkable migrants: Systematic analysis of the Western European insect flyway at a Pyrenean mountain pass

# The most remarkable migrants: Systematic analysis of the Western European insect flyway at a Pyrenean mountain pass [https://doi.org/10.5061/dryad.vq83bk40v](https://doi.org/10.5061/dryad.vq83bk40v) This dataset is four years of insect migration observations during the months of September and October moving through the 30m wide Pass of Bujaruelo, 2300m up in the Pyrenees. We collected this data using a video trap and a malaise trap. Meteorological data was collected from meteoblue forecasting. ## Description of the data and file structure The data is organised into an excel file with separate sheets for different aspects. These aspects are: Number of insects in the pass; Nutrient transfer calculations; Migratory strength data; Hoverfly species in the pass; Total assemblage; Butterfly migration data; Intercept trap data. **Number of insects in the pass** This dataset is an overview of the numbers of insects recorded migrating through the Pass of Bujaruelo. This contains all the data from the four years of data collection. The columns are: Year; Date; Ordinal date (an ordinal format for the multiples of a day elapsed since the start of year); Columns D to H are various environmental variables at the Pass of Bujaruelo obtained from MeteoBlue forecasts and models; Daily video counts (the number of insects recorded by the video camera each day); Small Insect Migratory Traffic Rate = (count/30m)/8hrs (this is the calculation of the migratory traffic rate in numbers of small insects per metre per hour moving through the pass); Daily butterfly counts; Butterfly Migratory Traffic Rate = (count/30m)/8hours (this is the calculation of the migratory traffic rate in numbers of butterflies per metre per hour moving through the pass). **Nutrient transfer calculations** This dataset contains a list of the species and families of migratory insects recorded moving through the Pass of Bujaruelo. An estimate for the weights of these insects were determined and listed in column D, the citation (if used) noted in column C. The total number of individual insects were then calculated in column E. The total biomass (in kg) of these insects calculated in Column F, then the estimated totals of Nitrogen and Phosphorous (nutrients limiting to plant growth) are in columns G and H. Finally, brief calculations on the biomass of the insects per day are included. **Migratory strength data** This dataset contains information on the migratory strength of the insects moving through the Pass of Bujaruelo. The southward score purports to the percentage of insects moving southwards on days when there is a headwind or a tail wind. 100% of the Pieris butterflies, for example, moved southwards during a headwind, and 100% moved southwards during a tail wind as well. The n/a values are because no insects representing the insect groups were recorded during tailwinds in the pass (it is thought that they were capable of migrating at higher altitudes during these weather conditions - see main manuscript). **Hoverfly species in the pass** This dataset contains a list of all hoverflies (Syrphidae) recorded migrating through the Pass of Bujaruelo including their estimated percentage of the total assemblage and their estimated numbers across the four years of data collection. **Total assemblage** This dataset contains an overview of the total assemblage of migratory insects in the pass. All recorded insects are listed here, including the ones deemed as non-migrants. Their percentage composition of the total assemblage is also included. **Butterfly migration data** This dataset contains a breakdown of the butterfly migration data collected each year. Including the raw numbers for headwind and tailwind days. Calculations for scaling the counts to account for the time between counts (*32) and to allow comparison with intercept trap data (/15) are also included. **Intercept trap data** This dataset contains an overview of the intercept (malaise) trap data. It contains raw counts for invertebrate families recorded including breakdowns for head and tailwind days for each year. The malaise trap was bidirectional which is why there are separate rows for south and north counts for each year. Blank spaces are present when that family was not recorded in the given year. Below the year by year breakdown are summaries of the total (four years) data collection. This includes breakdowns for head vs tail wind days, as well as north vs south trap direction collections. ## Code/Software R code is also provided for analysing the impacts of environmental conditions on the migration of the insects.