I'm mostly interested in number of individuals divided by total party hours for the count. Joe
On Fri, Apr 13, 2018 at 2:15 PM, Diana Beatty <[email protected]> wrote: > While I do think participation count and participation man hours matter, > it only goes so far. For example, having 2 people in an area report 10 > birds does not mean that 4 people should have found 20 birds - either group > might do equally well at finding the same birds present. The ability of the > participants and how exactly they cover their assigned area also matter but > there is little to no accounting for that in the data. It is a complicated > nut. That 1476 year is an apparent outlier from the rest of the data set, > although i did not calculate if it actually meets the mathematical > definition at this point. You can see in your graph it is quite far from > the rest of the data and something interesting may have been going on that > year worth exploring but that year may not be a particularly good data > point for discovering trends. I don't think one CBC data set is going to > be enough to say with much certainty if there is a real population thing > going on, but it is intriguing to examine the data anyway. > > Here's hoping our CBC participation continues that trend. :) > > Thanks, > Diana Beatty > > > > On Fri, Apr 13, 2018 at 1:54 PM, Douglas Eddy <[email protected]> wrote: > >> Hi again, >> >> After beginning some attempts at correcting for effort (thanks for >> pointing that out, Joe Roller!), I'm still playing with different ways to >> quantify things. I can share two possible points of interest: >> >> --Diana's suggestion that the 2016 count may have been low due to poor >> weather and thus participation doesn't seem to be reflected in the data; >> the effort for 2016 was much higher than in 1953 (for example), when only >> half the number of people recorded the highest count in the Colorado >> Springs dataset, 1476 birds! There were many years with less effort and >> more birds, which leads me to believe the low count in 2016 might very well >> reflect a real population thing going on. >> >> --I did a very simple regression of number of participants vs. year. As >> you can imagine, participation goes up over time. But it's the rate that's >> the fun part: The Colorado Springs CBC adds almost exactly 1 person every >> year! >> >> Cheers, birds, and amateur data analysis, >> Doug, Laramie, WY >> >> On Fri, Apr 13, 2018 at 1:00 PM, Diana Beatty <[email protected]> >> wrote: >> >>> 2016's low count is likely a product of the weather that day - we had a >>> blizzard with temps around 0 degrees Fahrenheit - some areas of the circle >>> may not have had the usual level of participation due to that weather, as >>> well. In reading all these posts a few questions that occurred to me were >>> 1. Is there a successional change in habitat at some of these feeders where >>> people are now reporting lower numbers that could be at play? Newer >>> housing developments tend to have slightly different habitat than more >>> established ones, for example. 2. Is there any relationship between the >>> success of EUDO in traditional House Sparrow habitat and House Sparrow >>> population fluctuations? Incidentally, I have not noticed decline in the >>> Security/Widefield/Fountain area but I haven't been keeping close data, >>> either. >>> >>> Diana Beatty >>> >>> >>> >>> On Fri, Apr 13, 2018 at 11:34 AM, <[email protected]> wrote: >>> >>>> Hi all, >>>> >>>> First off, hi! I'm brand new to this list. As dumb luck would have it, >>>> the first post I ever received was yesterday from Diana Beatty. She had the >>>> wonderful idea to do a linear regression on Christmas Bird Count (CBC) data >>>> from Colorado Springs to see if there has been a decline in House Sparrow >>>> population size since 1950. Due to my burgeoning interest in House Sparrows >>>> as a graduate student, I asked her if she had any more details. In >>>> response, she sent the raw data for me to have a look at. A big thanks to >>>> her for sending that along! >>>> >>>> Diana's analysis was of course correct: that is, that when looking from >>>> 1950-2017, there has been no overall trend toward decline. However, my eyes >>>> wouldn't stop perceiving little peaks and dips in the cloud of data points. >>>> So I split the data up and found that there have been 3 cycles of >>>> statistically significant growth and decline since 1950. We're currently in >>>> the middle of a decline that began in 2001. >>>> >>>> It's no surprise that there have been fluctuations in the 67 years of >>>> CBC data that we have. All wild populations fluctuate. The interesting part >>>> is telling a story as to why they fluctuate. Often, growth and decline >>>> cycles have something to do with climatic patterns, possibly interacting >>>> with things like competition and selection. Unfortunately, I'm not sure >>>> that I have the expertise to attempt any associations with climate or other >>>> factors right now. But it's likely there's something of interest going on, >>>> even if we don't know what it is! >>>> >>>> I'm attaching a visual representation of the CBC data to this post. I >>>> color-coded each of the cycles. The x-axis shows passage of time with the >>>> far left side being 1950 and the far right being 2017. On the y-axis is the >>>> CBC count data, with lower values on the bottom and higher counts up >>>> higher. Note that the red dots, spanning the years 1950-1984, represent the >>>> longest and slowest decline. The last 2 declines (the second of which we're >>>> currently in right now) occurred on much smaller time scales, from >>>> 1985-2000 (black dots) and from 2001-present (blue dots). The lowest ever >>>> count in the entire data set was in 2016 with only 177 House Sparrows >>>> reported. >>>> >>>> While it's likely that a population ecologist could point out several >>>> ways I've poorly described these patterns, I think it's cool that Diana >>>> began all this with an analysis of publicly-accessible data and shared it >>>> on a bird listserv. Thanks a lot to all of you for reading this, and I'd >>>> love to continue the conversation if anyone is interested! >>>> >>>> Good birding, >>>> Doug Eddy, Laramie, WY >>>> >>>> >>>> <https://lh3.googleusercontent.com/-W4ZLspoVpXs/WtDp4O0kJaI/AAAAAAAAEHs/uDW1KB6HAxM4nTqWldzLFY3x87o-QtHxgCLcBGAs/s1600/HOSP%2BCBC%2BCol%2BSprings.png> >>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Colorado Birds" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> To view this discussion on the web visit https://groups.google.com/d/ms >>>> gid/cobirds/7a82d6bf-457f-4222-9b0f-721b2a2d358e%40googlegroups.com >>>> <https://groups.google.com/d/msgid/cobirds/7a82d6bf-457f-4222-9b0f-721b2a2d358e%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> >>> >>> -- >>> >>> ****** >>> >>> All that is gold does not glitter, not all those who wander are lost; >>> the old that is strong does not wither, deep roots are not reached by the >>> frost. >>> >>> >>> >>> >> >> >> -- >> Doug Eddy >> PhD student, Carling Lab >> Program in Ecology (PiE) >> Department of Zoology & Physiology >> University of Wyoming >> www.carlinglab.com >> >> > > > -- > > ****** > > All that is gold does not glitter, not all those who wander are lost; the > old that is strong does not wither, deep roots are not reached by the frost. > > > > -- > You received this message because you are subscribed to the Google Groups > "Colorado Birds" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/cobirds/CAM-_j9v3UhXKBR%2BcJU3iMCE40BaX8mpF0hguG36YszY > HbKN8wA%40mail.gmail.com > <https://groups.google.com/d/msgid/cobirds/CAM-_j9v3UhXKBR%2BcJU3iMCE40BaX8mpF0hguG36YszYHbKN8wA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. 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