Hi All,
First, let me apologize for posting this on the listserv. I know these discussions are what the forum was created for and my initial response was to help address the questions that Laura posted to the list. I hope folks don't mind too much.
While Breeding Bird Survey (BBS) trend data between 1966-2005 seems to suggest that Kestrels have been decreasing across the United States by 0.1 % per year, interestingly the Ohio BBS data actually suggests that they've been increasing by 1.4 %/per year (see: http://tinyurl.com/2lnonj <http://tinyurl.com/2lnonj> ). If anyone wants to check the trend data themselves they can visit the Breeding Bird Survey page for Kestrels: http://tinyurl.com/3byge3
One of the things we have to remember is that BBS data is looking at abundance of breeding individuals, whereas Breeding Bird Atlas data is only looking for presence or absence of breeding indviduals. So in a Breeding Bird Atlas you could have 10, 100, 1000 individuals and it would only show up as present or absent. Breeding Bird Atlases are helpful in understand where birds are breeding in the state, whereas Breeding Bird Surveys help us get an idea of how many individuals are breeding. So if preliminary Breeding Bird Atlas data is suggesting that they've disappeared in some locations (for example in urban areas or areas undergoing development), it may also mean that they're breeding in other locations they may not have bred previously OR they are breeding in some locations in higher densities OR it may mean it's only the first year of a five year study and we need more observations to get a better picture of what is happening.
Jim's observation of CBC data regarding numbers of participants on CBCs and Kestrels is an interesting one. Unfortunately, we can't always assume that because there are more people out looking that we will see more birds. Additionally, just comparing two points is problematic because one point might have been from an unusual year where we had an influx of Kestrels into the state, or an outflow of Kestrels. For example, the 1995-96 count had 1399 Kestrels with 1300 observers, but the 1999-2000 count had 1390 Kestrels with 1251 observers. Additionally, the 1998-99 count had 928 Kestrels with 1095 observers and the 2005-2006 count had 975 Kestrels with 1437 obsevers. For these reasons it's better to look at trends, and take into consideration effort which is reported as party hours on CBCs.
I think before we can make claims about the impact of agriculture on Kestrels we have to get some better data on changes in land use for agricultural purposes as well as agricultural practices (no till vs. till, pesticide usage, etc.). Anecdotally, agriculture has been changing in the state. Medium-sized farms are disappearing either due to purchase by big industrial farms, or division into housing developments. That being said, small individual or family farms are also increasing, as are organic farms. Again, this is all anecdotal and would need to be supported by some actual data.
Interestingly, in September there will be a one-day symposium titled "Are American Kestrels in Decline?" that will explore this very issue. The symposium is being held in Pennsylvania. It will be interesting to see what comes out of that conference.
There's also a group called Kestrels Across America that has been working to promote the installation of Kestrel nest boxes. You can check them out here: http://www.kestrelsacrossamerica.org/
Obviously, regardless of whether they're decreasing or not anything that you can do, like the installation of a Kestrel nest box on your property and reducing use of pesticides, is beneficial for them and should not be discouraged. It's a good way of ensuring that you'll see them locally more often.
Again, I'd be more than happy to share the data analysis I generated with folks who are interested.
Thanks!
Casey Tucker
Columbus, OH
-----Original Message-----
From: Ohio birds on behalf of Jim McCormac
Sent: Sat 1/27/2007 12:38 AM
To: [log in to unmask]
Cc:
Subject: Re: [Ohio-birds] Am. Pipets in Holmes Co. & some thoughts on Kestrel populations
Hi Casey and all,
Wow! I hope you are right, but this conclusion flies in the face of much
research that has been done on American Kestrels in the Midwestern and
northeastern U.S. Many of us who spend lots of time traveling about and in
the field began noticing what seemed to be lower numbers of this beautiful
little falcon some years ago, and while this is less obvious in winter, when
there is an influx of wintering birds to Ohio, it is dramatic in many areas
during the breeding season. Kestrels really seemed to have dropped
dramatically or even disappeared in many areas of the state as breeders, and
Aaron Boone had looked at preliminary Breeding Bird Atlas data that seemed
to bear this out, although it is still too premature to make definitive
statements based on that data.
A quick analysis of Christmas Bird Count data, which anyone can do at:
http://www.audubon.org/bird/cbc/hr/index.html showed a statistically
significant drop in kestrel numbers in Ohio as a whole over the last decade.
Last year's counts produced a total of 975 kestrels, with a total of 1,437
observers on 56 counts. In contrast, one decade earlier the 1995-96 CBC's,
which also had 56 counts but only 1300 observers, produced 1,399 kestrels!
So, in spite of an equal number of CBC's and 137 more observers, 424 FEWER
kestrels were found last year as compared to ten years prior. This jives
with much of the anecdotal observations that I've heard from active field
reporters in Ohio in recent years.
This decline is supported with data from elsewhere. For instance, the
Breeding Bird Survey routes, which have been run since the 1960's, show a
drop of about 1.4% a year for the northeast region, of which Ohio is on the
western periphery of. Big hawk watches like Cape May and Hawk Mountain have
been documenting statistically significant declines in kestrel numbers in
migration in recent decades, too. An enlightening but somewhat depressing
report issued by Hawk Mountain can be found here
http://www.hawkmountain.org/raptor_conservation/CSR_AMKE.htm and seems to
largely mirror what we are seeing in Ohio.
Obvious problems for these little raptors include changes in overall
agriculture which have led to conditions that aren't so conducive to
providing good raptor habitat, and outright development. Regarding the
latter, a look at the last ten years of the Columbus CBC - an area typical
of rampant development associated with many bigger Ohio cities - shows a
real kestrel decline. Ten years ago, 23 kestrels were found on the Columbus
CBC; in 2005, only 8 were found.
American Kestrels are cavity-nesters, and a lack of suitable nesting sites
is probably hurting them, in addition to other factors. Placing nest boxes
in suitable sites will help, and Dick Tuttle of Delaware, Ohio has done this
in numerous sites and seen good results. The Ohio Ornithological Society has
been working with American Electric Power to explore the possibility of
erecting kestrel boxes in some of the vast reclaimed strip mine grasslands
of SE Ohio, and hopefully that effort will bear some good results
eventually. We are also looking at some other ways in which we might work
with organizations to help kestrels via nest box placement in good habitats.
Jim McCormac
Columbus, Ohio
-----Original Message-----
From: Ohio birds [mailto:[log in to unmask]] On Behalf Of
TUCKER, Casey
Sent: Friday, January 26, 2007 11:25 PM
To: [log in to unmask]
Subject: Re: [Ohio-birds] Am. Pipets in Holmes Co. & some thoughts on
Kestrel populations
Hi Laura,
I wanted to follow-up on your question regarding Kestrels in Ohio. After
the last discussion on the listserv about the status of this species in the
state I started looking at some Audubon Christmas Bird Count data to see if
I could discern any patterns in population trends.
I looked at Kestrel data (birds per party hour) from almost all of the CBCs
in Ohio between 1960 (61st count) and 2005 (106th count). Using this data I
was able to come up with a statewide trend for Kestrels in the state.
I went through each count in the state and categorized them into one of four
categories based on a rough estimation of the predominant habitat type
within each count circle. The four categories were rural, urban, areas
undergoing sprawl, or communities that have pretty much remained the same.
I then looked at Kestrel trends for each of the four habitat types and
compared them against the statewide trend.
My rough analysis of CBC data suggests that over-wintering Kestrels are
increasing statewide. However, they're increasing more in rural areas, and
slightly more in communities that have not undergone much change. They seem
to be decreasing pretty dramatically in urban areas. In communities
undergoing change (i.e. development) Kestrels seem to be leveling out.
Because over-wintering Kestrels seem to be increasing, based on this study,
in rural areas irrespective of region of the state or agricultural type
(which I did not examine) would potentially suggest that crop type or
herbicide use may not be a factor.
Again, this was just a rough analysis without any special statistical
analysis to determine significance, etc., and it's only looking at birds
recorded during the Christmas Bird Count period (mid-December to early
January). I can send copies of the graphs in a microsoft word document to
anyone who is interested in seeing them for themselves.
Hope this helps answer your question a little,
Casey
-----Original Message-----
From: Ohio birds on behalf of [log in to unmask]
Sent: Fri 1/26/2007 7:15 PM
To: [log in to unmask]
Cc:
Subject: [Ohio-birds] Am. Pipets in Holmes Co. & some thoughts on
Kestrel populations
Returning from our cottage in Coshocton Co. today, Tim & I drove
some back
roads in Holmes Co. & were lucky enough to find a flock of 10-20
American
Pipits feeding on some freshly spread manure. They were on CR 58
just west of
the intersection with T122 & T128. (Delorme 60A4--right above
the"N" in
Mechanic Township). Also saw a Rough-legged Hawk on T157, just
outside of Charm
(DeLorme 51D4).
While driving these roads we saw quite a few kestrels, more than we
have
seen in similar habitat in other rural areas of Coshocton, Stark,
Summit &
Portage counties. (The counties we drive most often). Remembering
the discussions
we have seen on this list-serve regarding possible kestrel
population
declines, we wondered what might be different in Holmes Co. Could
the use of
Round-up Ready crops that has become so popular in recent years be
a factor? It
is quite likely that these Round-up treated seeds are not used as
heavly on
Amish farms. These treated seeds result in less weeds, which
should mean less
insects & therefore less food for kestrels. Or could the insects
that are
present have toxins in them from the treated seeds? Would any of
this
hypotheses result in kestrels either dying or moving to other
areas, such as Holmes
Co.? Has anyone else noticed more kestrels in some counties that
have less
soybean/corn row crop production where Round-up Ready seed is more
prevelant?
Laura Dornan
Louisville, Stark Co.
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Our thanks to Miami University for hosting this mailing list.
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