DIY Big Year: Finding Hidden Treasure In Your Data

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Oct 5, 2017 | by Greg Miller

Awesome male Chestnut-collared Longspur in rich, breeding plumage – photo by Greg Miller

In my last post I introduced you to some different ways to look at the data that I have collected from eBird between 2006 and 2016 as of September 2016. Here it is a year later and I’m just writing about my findings. The data collected comes from 299 Counties in the U.S. having the greatest number of checklists submitted into eBird, an online database of checklists of birders from around the world.

As one grows older, one becomes acutely aware of how important time is. And how little of it exists to do everything you want to do. We live in an impatient society racing around trying to get things done. And our money gets stretched thin in trying to cut corners to save time. Add to all this a desire to do something fun. A hobby, like birding. How does one fit in that on top of all the responsibilities and obligations of life?

And if you’re reading this, you probably have at least a remote idea that you would like to do a Big Year—to see as many species as you can in one calendar year. But you lack, time, money, or health, or you face some other obstacle to keep you from doing it competitively for a whole year.

This is the why I am writing this series of posts. I want to help those who are tinkering with doing a personal Big Year. You want to break your own record. Where can you go to see the most species in the shortest amount of time? What time of year should you go?

EBird is a fabulous resource. You can look at data for a specific area. You can look at data for a specific species. You can look at bar charts of species for anywhere in the world. But it is not a complete picture of where all the birds are. What it does represent is the intersection of birders and birds. This data provides insight into how and when birders go birding as well as what birds they encountered.

One of my big assumptions for collecting data from the most eBirded Counties in the US was that these counties represent where birders go most often. If it is close to a populated area, then the reason is probably convenience. If it is a place without many people and there are still a lot of checklists, then this location probably merits a special trip.

Let’s see what we can find out from our data. Where and when do most birders go (when submitting eBird checklists, that is)?

Rank Location Most Checklists Submitted in a Week
1 Lucas County, OH 9,332 (May 8-14)
2 Galveston County, TX 4,835 (Apr 22-30)
3 Los Angeles County, CA 4,813 (Feb 15-21)
4 Cook County, IL 4,705 (May 1-7)
5 Pima County, AZ 4,196 (Apr 22-30)
6 Ottawa County, OH 3,844 (May 8-14)
7 Middlesex County, MA 3,826 (May 8-14)
8 Tompkins County, NY 3,750 (Apr 22-30)
9 San Diego County, CA 3,590 (Mar 1-7)
10 Essex County, MA 3,387 (Jan 22-31)

From the eBird data we can see that there are lots of birders who go to Lucas County, Ohio the second week of May. Many of you are probably familiar with The Biggest Week in American Birding. I suspect that festival has a large part to play in our data. But, it still stands to reason that birders like to hit a migration hotspot in pursuit of those little gems of the birding world called warblers. This is arguably one of the very best places to see a large number of warblers up close and personal. And if you were from Ohio, you would recognize this as one of the best times to see the most species of birds in the State.

The total number in the third column (9,332) is the total number of checklists submitted for Lucas County, Ohio during May 8-14 for all the years 2006-2016. That would mean roughly an average of 900 checklists are submitted to eBird for Lucas County, Ohio every second week of May. Does that make sense? I hope so.

You’ll notice Ranking #6 is Ottawa County, Ohio. This is a neighboring county to Lucas County, Ohio. It is also the same week as Lucas County. And both counties are affected by the festival.

This list is a pretty valuable cross section of good birding places and the times when many birders go there. But just because it is a popular place doesn’t mean it is necessarily the best or most efficient place to go. They are all good. But we want the best possible locations and times, don’t we?

Rank Location Most Recorded Species in a Week
1 Los Angeles County, CA 356 (Apr 22-30)
2 San Diego County, CA 345 (Oct 8-14)
3 Galveston County, TX 333 (Apr 15-21)
4 Cameron County, TX 320 (Apr 22-30)
5 Cochise County, AZ 316 (Apr 22-30)
6 Nueces County, TX 313 (Apr 22-30)
7 Monterey County, CA 311 (Sep 22-30)
8 Marin County, CA 310 (Sep 22-30)
9 Orange County, CA 307 (Jan 1-7)
10 Santa Barbara County, CA 305 (Sep 22-30)
10 San Francisco County, CA 305 (Oct 1-7)

Ok. Cool. Now we have more of what we really want. This is where and when the most species have been recorded between 2006 and 2016. The first thing that my eye sees is that every one of these counties has recorded over 300 species during one week of the year over the period of time between 2006 and 2016. The next thing that sticks out is the number of counties in California that are on this list. And Texas, too. Why is this so?

I bet some of you are already one step ahead of me. This includes all the birds ever seen during that one week between 2006 and 2016, including all the rare, only-seen-one-time birds. But if you go to Los Angeles County, California during the last week of April then you probably already know that you are not going to see all those 356 species of birds. You probably will not see 300 species either. And this only begs the question, “How many species can I expect to see in one week?” How does one get the answer to that question? Because that is the question that we really wanted to know from the beginning. Are you ready? Here we go.

Rank Location Highest Number of Expected Species in a Week
1 Cameron County, TX 193 (Apr 22-30)
2 Cameron Parish, LA 179 (Apr 22-30)
3 Brazoria County, TX 170 (Dec 15-21)
4 Galveston County, TX 168 (Apr 15-21)
5 Nueces County, TX 166 (Apr 15-21)
6 Hidalgo County, TX 164 (May 1-7)
7 Socorro County, NM 163 (May 1-7)
8 Monmouth County, NJ 162 (May 8-14)
9 Jackson County, MS 161 (Apr 15-21)
10 Grand Forks County, ND 158 (May 22-31)

Shazam! Now we are getting somewhere! Maybe. First, the best place to go birding is Cameron County, Texas. And the best time to go is the last week of April. Using my estimation (wait, what?) you should see approximately 193 species of birds. Note the use of estimation and approximately. Why would I use those when I have hard data? Great question.

How does one predict how many species a birder can see in one week? And by one week, I mean 7 days. Two days are for travel—the first and last days. I don’t know where any birder is coming from, so I cannot predict exactly how much time you’ll have at your destination. The next question—and the harder one—is how to predict how many species any birder is going to see in those remaining 5 days.

Here is where I wave my magic wand and poof! I produce answers. Well. It’s almost what I do. I don’t have a magic wand. But I have met thousands of birders of varying skills and abilities. The number I wanted to predict is what I “feel” is about what an average birder of average skill or ability might see in those 5 days.

EBird uses a metric they call Frequency of Checklists. The is the percent of positive checklists for a specific species for a particular week of the year. For example, we’ll say 1,000 checklists were submitted to eBird from the previously mentioned Lucas County, Ohio during May 8-14. Of those checklists 600 of them had recorded one or more Yellow Warblers. This does not differentiate between 1 Yellow Warbler or 35 Yellow Warblers. It’s a boolean yes-or-no kind of thing. The resulting Frequency of Checklists would be 600 divided by 1,000 or 60%. This number gives us a probability of seeing a particular species.

EBird also requests that birders submit checklists for each visit to each location. If you go birding at 3 locations in one day, you will submit 3 checklists to eBird. In 5 days at 3 locations per day you would submit 15 checklists. Knowing how this works leads us to the next step.

Here is how to translate Frequency of Checklists into number of trips required to see a species. Take the Yellow Warbler example above. The Frequency of Checklists is 60%. So 100% divided by 60% would equal 1.67 random trips during May 8-14 in Lucas County to see a Yellow Warbler. And really, no one takes 1.67 trips. One plus a fraction equates to 2 trips in real life. But if you knew where to go or at least visited the right habitat your chances would increase.

My goal is to give birders reading this information enough of a chance to get to the 3% level of Frequency of Checklists. If you plan well and are familiar with your targets then you will be far more successful. (For you fellow geeks out there, the 3% level of Frequency of Checklists means a birder would have to visit 33 random locations in 5 days or about 7 locations per day).

The count of 193 species for the last week of April for Cameron County, Texas represents all the species that have a Frequency of Checklists of greater than or equal to 3%. This is the yardstick—the standard of measure that I will be using throughout the rest of these blogs about doing your own Big Year.

A skilled birder with well planned itinerary and lucky migration conditions can see over 200 species of birds here. If you don’t plan, don’t know birds, and/or hit cruddy conditions you may find 180 species or less.

So my eBird data pointed me to Cameron County, Texas during the last week of April. Does this make sense? Yes, it does. Maybe you thought Cameron County, Texas was where High Island is located. Nope. High Island is in Galveston County, Texas. It’s on the list and ranked #4. Cameron County is the southernmost county in Texas. It’s on the Rio Grande River and borders the Gulf of Mexico. The county seat is Brownsville. It is home to the Rio Grande Valley Birding Festival in Harlingen each fall. Laguna Atascosa NWR is in Cameron County and so is South Padre Island. So Cameron County has lots of those incredible Rio Grande Valley specialty birds as well a good number of migrants that show up on South Padre Island. The beaches are great for shorebirds and the marshes hold an amazing variety of rails. Eastern and Western migrants pass through here. It can be amazing.

So now you have your best location to visit and the best week to go. And you get to see all 193 species that are expected. Where do you go next? The best time for #2 Cameron Parish, Louisiana is also the last week of April. To be at both places at the same time would be hard as they are several hundred miles apart. Unfortunately, there is no app for that…yet. If you look at the other locations, many are along the Texas Coast and they are also roughly the same time period. You may get a few new birds. But a lot of those species are going to overlap.

And the next post? It is to answer “Where do I go next?” The longer, more specific question is “Where is the best place to go to get the most new species of birds that I have not already seen?” And now you’ll have some time to think about how one should come up with an answer to this.


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