Bumping this to show people who may not know about it that the
eBird Polygon Tool exists.
I've made several improvements to it since starting this thread. Most significantly, because eBird removed the 50 location limit on barchart queries, I added support for specifying the maximum number of locations, up to 1500. The actual number of locations returned depends on how many can fit within the maximum URL length, but for non-enormous polygons, it can often return
all locations rather than just the top ones. See the
changelog for the full list of changes.
Also, be aware that there is a bug in eBird's bar chart functionality, where if you are logged on to eBird, the types of bar chart URLs returned by the Polygon Tool (which include not just hotspots, but personal locations as well) will usually fail to load properly, and show only a tiny subset of the data (or even a completely empty bar chart). I reported this bug to eBird support back in Aug 2018 but they did not reply, and did not fix the bug. So to make proper use of the Polygon Tool, you should either be logged off eBird or use a Private/incognito browser window.
Since Oct 2018, eBird has been archiving their database once a month (instead of the previous 4 times per year) and I have been taking advantage of this to update the Polygon Tool's location database once a month.
This would not be possible given the way the tool currently works. It would have to be interfaced with your eBird account, whereas currently it has no knowledge of which user you are and does not connect directly to eBird's site (rather, leaving it up to you to open the URLs it provides).
One way this could
almost work would for a browser extension to do the following two queries:
- Your list of target species (which could come from a query to eBird's existing Target Species function, over an area that is a superset of the desired polygon)
- The output of the bar chart query from following the URL provided by the existing Polygon Tool.
This browser extension would parse the data from these two queries, and create a page (that mimics the Target Species results page) containing an intersection of the species contained both in the Target Species result and the bar chart result. This wouldn't be correct though, which is why I said
almost. Since the Target Species query would have to be done to an area that is a superset of the polygon, it will omit species that you have seen within the larger area (e.g. county) but have not seen in the polygon (e.g. local patch).
The only way this could
truly work (short of eBird integrating polygon functionality) is for a locally executed tool to take the data returned by eBird's
Download my Data function (you'd have to manually give it the MyEBirdData.csv file you received over email), intersect that with the desired polygon and time period, and invert the resulting list of species. You'd have to re-download your eBird data via the "Download my Data" function every time you wanted an up-to-date polygon needs list. It wouldn't need any location database, because the latitude and longitude data is already in the MyEBirdData.csv file; it'd only need a species database. Would anybody be interested in a tool that does this?
Correct. The list of locations in the bar chart URL is from a snapshot of the eBird database (which, as of the more frequent updates, can be anywhere from 15 to 52 days out-of-date), but the bar chart itself is from the current database
