[BCNnet] Henslow's abundance
judymellin
judymellin@netzero.net
Mon, 1 Dec 2003 18:17:16 -0800
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I looked at the BCN eBird site and found some amazing statistics- and =
they don't look good. I also used the main Cornell eBird site, focusing =
on IL., and it doesn't look any better. But please know that statistics =
are not my forte!
For those not familiar with these sites, Cornell Lab of Ornithology =
established a wonderful site (http://www.ebird.org/) for listing species =
by date that allows birders and others (especially scientists) to track =
what they are seeing- for free! =20
BCN then had Cornell establish a separate site for IL. postings =
(http://www.ebird.org/BCN/); however, at this time, one system does not =
"talk" to the other so, unless folks input into both Cornell and BCN, =
the results show only on one site or the other.
In BCN, I looked at 1999-2003 and simply divided the number of times =
Henslow's sparrows were seen in June by the total number of observations =
posted for the month of June. I did notice that, without exception, the =
vast majority of sightings were in June. This would be indicative of =
the emphasis that is put on the Grassland Blitz in June beginning in =
2001 but, over the years, there were only one sighting in April, four in =
May, two sightings in July and one in August so, either the birds are =
not nesting here or we as birders are not following up with input on =
observations later in the season. I don't think trying to figure out =
numbers of individuals per observations would be valid unless it was =
computed as birds/person hour of monitoring as we do on the various Bird =
Counts.
1999 11 sightings/19 observations 58%=20
2000 34 sightings/91 observations 37%
2001 40 sightings/714 observations 6%
2002 49 sightings/725 observations 6%
2003 44 sightings/228 observations 19%
On the main Cornell site, I found only a total of nine sightings from =
1999-2003, although there were 5 in June, 2003 (5 sightings/146 =
observations- 3%) as opposed to one or none in previous years. I'm not =
sure there is any way to merge the data from one website to the other as =
some of us have posted in both.
I tried to look at 1998 for both sites but, on BCN, there were only two =
observations and, on Cornell, only 18 (these early years on Cornell =
reflect only the data I have input from Poplar Creek) with no Henslow's =
sparrows reported.
But, as usual, these stats raise lots of questions:
1. The huge drop in percentages in 2001 and 2002 directly relates to =
the huge increase in observations. Yet the number of sightings in 2003 =
is very comparable to the numbers in the previous two years while the =
number of observations dropped by 2/3s. Does this mean that the prime =
sites for Henslow's sparrows were being monitored all along and that =
monitoring more sites does not turn up more birds? =20
2. Why did the number of observations drop so dramatically in 2003?
3. Do these numbers indicate that possibly the stability/increase in =
numbers is actually occurring on CRP land that is being monitored =
separately from our sites?
4. Are the numbers outside the Chicagoland area really as poor as those =
being reported in Cornell's eBird?
I have the breakdown on numbers of this species seen on the Cook County =
Spring Bird Count for about 15 years and, as soon as I get the most =
recent few years, I will post those numbers.
I believe the BCN site reflects mainly observations in the Chicagoland =
area while the Cornell site would be used more by folks in other parts =
of the state. Of course, I think we all put inputting data at the =
bottom of our list of favorite things to do but, I believe, at times =
like this, we are truly lacking good information.
Judy Mellin
Bird Monitor
Poplar Creek Forest Preserve=20
Hoffman Estates (Cook County)
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<DIV>I looked at the BCN eBird site and found some amazing statistics- =
and they=20
don't look good. I also used the main Cornell eBird site, focusing =
on IL.,=20
and it doesn't look any better. But please know that statistics =
are not my=20
forte!</DIV>
<DIV> </DIV>
<DIV>For those not familiar with these sites, Cornell Lab of Ornithology =
established a wonderful site (<A=20
href=3D"http://www.ebird.org/">http://www.ebird.org/</A>) for listing=20
species by date that allows birders and others (especially =
scientists) to=20
track what they are seeing- for free! </DIV>
<DIV> </DIV>
<DIV>BCN then had Cornell establish a separate site for IL. =
postings (<A=20
href=3D"http://www.ebird.org/BCN/">http://www.ebird.org/BCN/</A>); =
however, at=20
this time, one system does not "talk" to the other so, unless folks =
input into=20
both Cornell and BCN, the results show only on one site or the =
other.</DIV>
<DIV> </DIV>
<DIV>In BCN, I looked at 1999-2003 and simply divided the number of =
times=20
Henslow's sparrows were seen in June by the total number of observations =
posted=20
for the month of June. I did notice that, without exception, the =
vast=20
majority of sightings were in June. This would be indicative of =
the=20
emphasis that is put on the Grassland Blitz in June beginning in =
2001 but,=20
over the years, there were only one sighting in April, four in May, two=20
sightings in July and one in August so, either the birds are not nesting =
here or=20
we as birders are not following up with input on observations later in =
the=20
season. I don't think trying to figure out numbers of individuals per=20
observations would be valid unless it was computed as birds/person hour =
of=20
monitoring as we do on the various Bird Counts.</DIV>
<DIV> </DIV>
<DIV>1999 11 sightings/19 observations 58% </DIV>
<DIV>2000 34 sightings/91 observations 37%</DIV>
<DIV>2001 40 sightings/714 observations 6%</DIV>
<DIV>2002 49 sightings/725 observations 6%</DIV>
<DIV>2003 44 sightings/228 observations 19%</DIV>
<DIV> </DIV>
<DIV>On the main Cornell site, I found only a total of nine sightings =
from=20
1999-2003, although there were 5 in June, 2003 (5 sightings/146 =
observations-=20
3%) as opposed to one or none in previous years. I'm not sure =
there is any=20
way to merge the data from one website to the other as some of us have =
posted in=20
both.</DIV>
<DIV> </DIV>
<DIV>I tried to look at 1998 for both sites but, on BCN, there were only =
two=20
observations and, on Cornell, only 18 (these early years on Cornell =
reflect only=20
the data I have input from Poplar Creek) with no Henslow's sparrows=20
reported.</DIV>
<DIV> </DIV>
<DIV>But, as usual, these stats raise lots of questions:</DIV>
<DIV> </DIV>
<DIV>1. The huge drop in percentages in 2001 and 2002 directly =
relates to=20
the huge increase in observations. Yet the number of sightings in 2003 =
is very=20
comparable to the numbers in the previous two years while the number of=20
observations dropped by 2/3s. Does this mean that the prime sites for =
Henslow's=20
sparrows were being monitored all along and that monitoring more sites =
does not=20
turn up more birds? </DIV>
<DIV> </DIV>
<DIV>2. Why did the number of observations drop so dramatically in =
2003?</DIV>
<DIV> </DIV>
<DIV>3. Do these numbers indicate that possibly the =
stability/increase in=20
numbers is actually occurring on CRP land that is being monitored =
separately=20
from our sites?</DIV>
<DIV> </DIV>
<DIV>4. Are the numbers outside the Chicagoland area really as =
poor as=20
those being reported in Cornell's eBird?</DIV>
<DIV> </DIV>
<DIV>I have the breakdown on numbers of this species seen on the Cook =
County=20
Spring Bird Count for about 15 years and, as soon as I get the most =
recent few=20
years, I will post those numbers.</DIV>
<DIV> </DIV>
<DIV>I believe the BCN site reflects mainly observations in the =
Chicagoland area=20
while the Cornell site would be used more by folks in other parts of the =
state. Of course, I think we all put inputting data at the =
bottom of=20
our list of favorite things to do but, I believe, at times like =
this, we=20
are truly lacking good information.</DIV>
<DIV> </DIV>
<DIV>Judy Mellin</DIV>
<DIV>Bird Monitor</DIV>
<DIV>Poplar Creek Forest Preserve </DIV>
<DIV>Hoffman Estates (Cook County)</DIV></BODY></HTML>
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