<div dir="ltr"><div class="gmail_default" style="font-size:large;color:#073763">John Fitzpatrick of Cornell Lab (retired now?) spoke in broad strokes about eBird's Trends methodology at a WOS talk a couple years ago (during the pandemic shutdown). I think it's not recorded. </div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763">The biggest challenge, as you might imagine, is that eBird use increases about 30%/yr, or at least did at some point, and they are calculating trends from 2007 to 2021. Many didn't start using ebird until about 2012 or much later. So, using raw numbers, every bird is probably increasing dramatically. They had to correct for a massive increase in observer effort over time. </div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763">I remember they used presence/absence data only, not counts, so they're focusing on the odds of detecting a bird on a checklist ("frequency"). That's crude, but over time probably approximates "abundance." And, most importantly, they only used eBird checklists from certain experienced observers going to the same places repeatedly -- and these were chosen by a computer algorithm. The computer knows which species you should be seeing with what frequency, and at some point it cuts off checklists that don't meet some criteria. So basically they mined the data for the most comprehensive checklists. </div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763">He implied their methods would be published, but I'm not sure if this is that publication or a later one, and perhaps the original one is out there. Let me know if you find it! </div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763"><br></div><div class="gmail_default" style="font-size:large;color:#073763"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Aug 15, 2023 at 1:15 PM Robert O'Brien <<a href="mailto:baro@pdx.edu">baro@pdx.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Wow, thanks. I did not know that was so easily available. <div>As a test I just compared Rufous vs. Anna's Hummingbirds</div><div>No great surprise that Anna's are on the increase, most especially around urban areas. SeaTac and then PDX</div><div>Sadly Rufous is the reverse-strong decrease everywhere. I have certainly observed this here SE of Portland over the last 50 years.</div><div>I could describe further, but very easy for interested birders to check for themselves</div><div><br><div>But, do you know of a scientific paper or report that describes how they arrive at the trends? Correction for observer effort, accuracy and precision over time, etc.?</div><div>Thanks again, Bob OBrien Portland</div><div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Aug 14, 2023 at 1:16 PM Steve Hampton <<a href="mailto:stevechampton@gmail.com" target="_blank">stevechampton@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)">Ah, this is the science paper behind eBird's amazing Trends maps. They are remarkable. In some instances I was able to compare them with other data (e.g. surveys or even CBC data) and they lined up pretty well. </div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)">To see them, go to <b>eBird</b>, click the <b>Science </b>tab, then <b>Status & Trends</b>, and then type in a species name. </div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)">It defaults to the <b>Abundance </b>map, which is a basic range map color coded for abundance -- by season. You can then click on <b>Trends </b>and see the red, white, and blue dots. If you hover over them, the detailed trend appears. </div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)">For example, if I hover over the dot nearest Seattle for Spotted Towhee, it says declined 28%. That is since 2007 (there's a legend on the upper right). </div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)">These are wonderful maps -- each dot on each map is like a survey of its own. </div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div><div class="gmail_default" style="font-size:large;color:rgb(7,55,99)"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Aug 13, 2023 at 2:01 PM Alan Roedell <<a href="mailto:alanroedell@gmail.com" target="_blank">alanroedell@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">Interesting article. My impression after living in Seattle for 80 years, is that most species have declined. Crows and accipiters buck the trend.<div dir="auto">I miss the swallows most.</div><div dir="auto">Alan, Seattle </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Aug 13, 2023, 12:52 PM Dan Reiff <<a href="mailto:dan.owl.reiff@gmail.com" target="_blank">dan.owl.reiff@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
<a href="https://phys.org/news/2023-08-machine-learning-method-population-trend-bird.html" rel="noreferrer noreferrer" target="_blank">https://phys.org/news/2023-08-machine-learning-method-population-trend-bird.html</a><br>
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