LISTSERV mailing list manager LISTSERV 16.5

Help for VTBIRD Archives


VTBIRD Archives

VTBIRD Archives


VTBIRD@LIST.UVM.EDU


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

VTBIRD Home

VTBIRD Home

VTBIRD  September 2019

VTBIRD September 2019

Subject:

Re: August swallow numbers .... a look at the eBird data

From:

Leslie Nulty <[log in to unmask]>

Reply-To:

Vermont Birds <[log in to unmask]>

Date:

Sun, 15 Sep 2019 18:12:16 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (201 lines)

yes - thanks

On Sun, Sep 15, 2019 at 9:39 AM Ian Worley <[log in to unmask]> wrote:

> Hi Leslie,
>
> When you enter the species, dates, and location into the eBird graphing
> tool, it produces graphs from which directly or indirectly you can
> determine these data: the total number of checklists, the number of
> checklists with the species, high and average bird counts, number hours
> spent birding, and probably one or two things I not thinking of just
> now.  Some of these data are directly accessed from the various graphs,
> or calculated.  The graphs also produce outputs such as frequencies,
> high counts, birds/hour, and so forth.  It is also possible to download
> the data the produced the graphs.
>
> Regarding the number of checklists, as you suggest that is critical in
> many analyses where a limited number of checklists makes unreliable
> results. Hence those necessary data types are usually readily available
> on the graph pages.  For example, there are separate bar graphs for
> either the total number of checklists (per week) or the total number of
> checklists with the species (per week).  As I pointed out, eBird's
> "abundance" does not work well the small the number of overall checklists.
>
> Only "complete" checklists are used in the graphs, and any species
> submissions under review are not included.
>
> As with any analysis, a first look at what the data show regarding a
> question of interest, usually begs for more detailed analyses.  This
> often will seek additional data sources.
>
> One of the first "next level" inquiries that would follow a use of eBird
> "abundance" data would be to parse out the contributions of number
> checklists with the species from the number of birds per checklist.
> With migrating species, such as swallows, one checklist of 1000, or
> 100,000 Tree Swallows, could completely nullify the use of "abundance"
> as a comparative number.
>
> Does this get to what you are asking?
>
> Cheers,
>
> Ian
> ========================================
>
>
>
> On 9/15/2019 9:05 AM, Leslie Nulty wrote:
> > How can you correct this for "reporting errors?"  Have you checked how
> many
> > checklists were submitted each year?
> >
> > On Sun, Sep 15, 2019 at 8:55 AM Ian Worley <[log in to unmask]> wrote:
> >
> >> Hello all!
> >>
> >> Near the end of August there were a number of birders wondering about
> >> swallow numbers in Vermont.  It seem as if there were not nearly as many
> >> as in previous years.
> >>
> >> To see if this was really the case, I thought I'd use eBird data to
> >> compare 2019 August data with the corresponding data for the preceding
> >> five years (2014-2018).  I chose the eBird "abundance", taking the data
> >> from the eBird graphs.
> >>
> >> "Abundance" is the average number of birds reported on all checklists
> >> within a specified date range and region (for us that means August and
> >> Vermont).  It is a rather esoteric number, good for the comparisons we
> >> are interested in here, though rather hard to relate the numbers to any
> >> one specific birding outing.  The principal caution in this analysis is
> >> that the fewer the number of checklists the less meaningful the
> >> "abundance" number.  This is one reason for looking at the whole state's
> >> numbers.
> >>
> >> Basically, a higher "abundance" number mean more birds in the
> >> geographical area of interest.  The higher the number, expect to see the
> >> species more often and/or in larger numbers.
> >>
> >> Details are below, but first the grand results ------
> >>
> >> ----- For all five species of swallows combined, August 2019 had fewer
> >> swallows than any of the five preceding Augusts.  The abundance of
> >> swallows in August 2019 was only 67% of the average August abundance of
> >> swallows over those five preceding years.
> >>
> >> ----- Species by species, the abundance of birds in August 2019 was
> >> sometimes greater and sometimes less than during one or more of the
> >> previous five years.
> >>
> >> ----- Otherwise, the numbers from year to year show no abundance trends,
> >> either for the individual species or for all swallows as a whole (albeit
> >> this look is only six years).  For example, the abundance numbers for
> >> all species of swallows for the whole state from 2014 to 2019 are:
> >>
> >> 2014    9.64
> >> 2015    11.01
> >> 2016    8.55
> >> 2017    11.83
> >> 2018    7.81
> >> 2019    6.55
> >>
> >>
> >>
> -----------------------------------------------------------------------------------------------------------
> >> Here are comparisons for each of the species from the most abundant
> >> specie to the least, as per 2019.
> >>
> >> Barn Swallow [2019 August abundance 0.91]
> >> --- 2019 fewer than two years, greater than three years
> >> --- 90% of previous five year average
> >> --- Most abundant in 2014; least abundant in 2017
> >>
> >> Tree Swallow [2019 August abundance 0.56]
> >> --- 2019 fewer than all five previous years
> >> --- 42% of previous five year average
> >> --- Most abundant in 2017; least abundant in 2019
> >>
> >> Bank Swallow [2019 August abundance 0.03]
> >> --- 2019 fewer than one year; greater than four years
> >> --- 53% of previous five year average (data skewed by very large
> >> abundance in 2018)
> >> --- Most abundant in 2018; least abundant in 2014
> >>
> >> Northern Rough-winged Swallow [2019 August abundance 0.013]
> >> --- 2019 fewer than three years, greater than two years
> >> --- 108% of previous five year average
> >> --- Most abundant in 2018; least abundant in 2016 and 2017
> >>
> >> Cliff Swallow [2019 August abundance 0.01]
> >> --- 2019 fewer than all five previous years
> >> --- 30% of previous five year average
> >> --- Most abundant in 2017; least abundant in 2019
> >>
> >> All species combined [2019 August abundance 6.17]
> >> --- 2019 fewer than all five previous years
> >> --- 63% of previous five year average
> >> --- Most abundant in 2017; least abundant in 2019
> >>
> >>
> >>
> -------------------------------------------------------------------------------------
> >> I thought I'd take a peek at county-level data, wondering if 2019 county
> >> August abundance values different from the state as a whole values.
> >> Here are three county comparisons.  As suspected, the counties vary in
> >> terms of the number birds per species; to get the full picture for the
> >> distribution and abundance of the swallow species one really needs to
> >> look at all the counties.
> >>
> >> Barn Swallows
> >> --- Vermont  0.91
> >> --- Chittenden County  0.87
> >> --- Windham County  0.60
> >> --- Washington County  0.03
> >>
> >>
> >> Tree Swallows
> >> --- Vermont  0.56
> >> --- Chittenden County  0.35
> >> --- Windham County  0.34
> >> --- Washington County  0.10
> >>
> >>
> >> Northern Rough-winged Swallows
> >> --- Vermont  0.013
> >> --- Chittenden County  0.12
> >> --- Windham County  0.00
> >> --- Washington County  0.00
> >>
> >>
> >> Bank Swallows
> >> --- Vermont  0.03
> >> --- Windham County  0.05
> >> --- Chittenden County  0.01
> >> --- Washington County  0.0
> >>
> >>
> >> Cliff Swallows
> >> --- Vermont  0.01
> >> --- Chittenden County  0.02
> >> --- Windham County  0.00
> >> --- Washington County  0.00
> >>
> >> Best to all ...............
> >>
> >> Ian
> >>
> >
>


-- 
Best regards,

Leslie

Leslie Nulty
P.O. Box 1121
Jericho Center, VT 05465
home office: 802-899-4582
cell: 802-324-1496

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
September 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
November 2003
October 2003
September 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
November 2002
October 2002
September 2002
August 2002
July 2002
June 2002
May 2002
April 2002
March 2002
February 2002

ATOM RSS1 RSS2



LIST.UVM.EDU

CataList Email List Search Powered by the LISTSERV Email List Manager