This will build a csv file that attempts to model seasonality data based on an upload of a database (also in csv format).
Hopefully it's fairly self-explanatory. You need a file with names and dates at minimum. Select the file. Count the fields and find the one with the name and the one with the date and fill those numbers in. For example, an AviSys export is 1 and 5 and an eBird download is 2 and 11. Next, pick the months to include. Finally, pick how many segments to break each month into (1 means the whole month, 2 means 1-14 and 15-30/31, etc). If the month doesn't break evenly, the final segment will be slightly longer. Submit and you should download a file with the results. Name and then number of years reported per segment.