eBird 6% Rule

Before I go on a trip outside my local patch, like the recent London trip, I check eBird to see what species might be seen. For most birding spots eBird gives a good overview. You can do this if you are registered with eBird or not.

Before I go into details let me say this might look complicated, but it isn’t. If you have basic spreadsheet experience the following takes less than 5 minutes. If it isn’t clear leave a comment and I’ll try to clear it up.

The first thing is check to see if the area as caught on in eBird. Go to the EXPLORE DATA tab and choose EXPLORE A REGION. Then scroll down to London, England.

eBird - Explore London

Choose BAR CHARTS.

BarChart

London’s Bar Chart comes up.

LondonBarChart

By looking at the bar chart you can tell if the area has caught on in eBird. If the green lines are mostly narrow you know not many people have submitted eBird lists. In this case the green distribution lines are thick so we can tell it has been birded. You could go through the bar chart and make your own list but what I like to do is download the data.

Go to the bottom of the chart and select DOWNLOAD HISTOGRAM DATA.  This will download a CSV text file that you need to open with your favorite spreadsheet software. I’ll be using Microsoft Excel.

HistogramData

This is how the histogram looks when it’s opened.

HistogramInfo

Then manipulate the spreadsheet as follows:

  1. Delete rows 1-9

Instructions 1

2. Delete all the columns except for the week before the trip, the actual week, and the week after, leaving 3 weeks. In this case the last week of March and first two weeks of April.

Instructions 2

3. Insert a new column and number all species in ascending order.

Instructions 3

4. Sort on column D in Descending order Largest to Smallest

Instructions 4

5. Change the values to 2 decimals.

Instructions 5

I found out Eurasian Coot is the most common bird seen in London the first week of April. Sometimes I add all 3 columns and take an average.

I then look for birding spots where I could probably see most of these species and see if the spots fit the timing and logistics of the trip. I did the previous steps with 4 or 5 London eBird Hotspots and right or wrong came up with Hyde Park and the London Wetlands Centre.

My final list had 64 possible birds between the two sites with a frequency of 6% or greater. I ended up seeing 55 of the 64 or 86%. Plus I saw 2 species not on the list. A Common Buzzard and a bird which will be the topic of the next London blog.

Of the 9 I didn’t see there were 3 I probably could have seen with a little more time – Great Spotted Woodpecker, Eurasian Jay, and Mistle Thrush. But they’ll be there on the next trip.

On trips involving more birding than vacation, like last years Colorado trip, the percentage level can easily be pushed down to the 2-3% level.

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