I have seen many references to the idea that buckthorn causes diarrhea in
birds. Not this note but other articles. So here is a link to an article
that refutes that belief. I also have copied a relevant passage from the
article.
http://net-results.blogspot.com/2011/11/myth-busting-birds-buckthorn-and.html
Quote from article below.
"Wherever it occurs, buckthorn tends to be distributed by birds. There are
two commonly held and frequently repeated notions about buckthorn fruit:
that it causes diarrhea in birds, and that birds in North America don't
"know" not to eat unripe fruit and can become very sick or even die from
eating it. (Actually, there is a third notion, that buckthorn fruit is "junk
food." That isn't entirely true either, but it a subject of a future post.)
Jeff Stephenson
1323 28th ST SW
Rochester, MN 55902
Cell: 507 254 8194
Home: 507 289 7635
-----Original Message-----
From: Wayne
Sent: Friday, December 7, 2018 9:41 AM
To: [email protected]
Subject: Re: [mou-net] Winter Robins
Before I removed the buckthorn on my property, I had periodic flocks of
waxwings feeding on berries in January. I did some research and found the
following: While birds do eat buckthorn berries, it's often because it's the
only available seed source. But buckthorn berries are not a good food
source. They're low in protein and high in carbohydrates and produce a
severe laxative effect in some animals.
Wayne Swanson Minnetonka
On Thursday, December 6, 2018, 10:40:50 PM CST, Terence Brashear
<[email protected]> wrote:
I know when I ran the CBC for the Audubon Chapter of Minneapolis we found a
huge flock feeding on Buckthorn berries in Island's of Peace Park in
Fridley, MN in 2001. It was a flock of over 1000 birds. I think their
winter numbers are tied to food, and temperature.
On Thu, Dec 6, 2018 at 6:18 PM JULIAN SELLERS <[email protected]> wrote:
I think hackberries play a role. I don't know when the cities began
planting hackberry trees on boulevards, but I think it was not many
decades
ago. Most of the trees do not look very old. Did large crops of
hackberries begin to appear within the last 10 or 15 years?
On the 2008 St. Paul (North) CBC, my team had the area west of Cleveland
Avenue and south of Marshall Avenue/Lake Street, extending south to the
Ford Dam and west past the Hiawatha grain elevators in Minneapolis. We
counted 808 American Robins. As I recall, about 650 of them were feeding
on Hackberries on the Summit Avenue median in the two blocks between
Cretin
and Cleveland Avenues.
It seems to me that robins become scarcer in late December, as the
hackberry supply is depleted.
Julian
________________________________
From: Minnesota Birds <[email protected]> on behalf of Rebecca Field <
[email protected]>
Sent: Thursday, December 6, 2018 6:21 PM
To: [email protected]
Subject: Re: [mou-net] Northern Raven/Number Winter Robins
I just heard this evening that Robins eat Buckthorn berries. Of course, we
are trying to eradicate that invasive. I hope that isn’t causing less food
for the robins.
Becky Field
Sent from my iPhone
> On Dec 6, 2018, at 5:36 PM, Jason Frank <[email protected]> wrote:
>
> It would be interesting to compare the data of outstate CBCs as well.
> I haven't lived in Minneapolis during winter since 1997, and it seemed
> noteworthy to me to see large numbers of robins in the winter. A few
> years ago I visited Minnehaha Falls around Christmas and couldn't
> believe how many there were, though I just figured they were local
> birds who stayed for the open water along the creek and had reliable
> food sources nearby. Those numbers from Val show a pretty stark
> increase, which to my eyes fits the trend of climate change.
>
> But... having lived in the Lac qui Parle area since 09, I can't say
> I've seen many impressive winter flocks except during the mildest
> winters of the last decade, and those birds were usually seen in town
> or at parks, and not out in the countryside for the most part.
>
> Since the Twin Cities urban heat island effect means the temperature
> averages there would be trending warmer than elsewhere in the state, I
> wonder if outstate robins have gotten into the habit of migrating into
> cities and towns, rather than further south? Collating banding data
> with rural CBCs might shed some more light on the case.
>
>> On 12/6/18, GREG ELIZABETH CLOSMORE <[email protected]> wrote:
>> Buckthorn!
>>
>>> On Dec 6, 2018, at 4:32 PM, Val Landwehr
>>> <[email protected]> wrote:
>>>
>>> I was intrigued by the discussion of whether in recent years
>>> more robins are being seen during winter in the Twin Cities(Charles
Neil,
>>> Mary White and J. Baumann). I think that I
>>> have seen more robins, particularly in large flocks, in
>>> recent years. To put this hypothesis to the test I looked at the
>>> results from four Christmas Bird Counts over the years that are
>>> online at the Minnesota Ornithologists' Union website. The
>>> Christmas Bird Counts I checked were Bloomington CBC, St. Paul
>>> (North) CBC, Excelsior CBC and the Minneapolis (North) CBC.
>>> I found a distinct trend of more robins being counted during
>>> the counts since the winter of 1996 than were in prior years.
>>> The numbers vary widely each year, but there is a distinct
>>> inflection point around 1996 for a larger number of robinssince that
date
>>> than prior to it. Since 1996, the number ofrobins counted varies
greatly
>>> from year to year, but I don't
>>> see any clear evidence that the numbers are continuing to
>>> increase.
>>> Average number of robins counted at Twin Cities CBCs:
>>> Bloomington St. Paul (North) Minneapolis (North) Excelsior
>>> Pre 21.2 17.1 2.5
>>> 5.3
>>> 1996
>>> 1996- 367.4 420.5 114.6
>>> 181.2
>>> 2017
>>>
>>> Median number of robins counted at Twin Cities CBCs:
>>> Bloomington St. Paul (North) Minneapolis (North) Excelsior
>>> Pre 5 6 0
>>> 1
>>> 1996
>>> 1996- 278 255 26
>>> 132
>>> 2017
>>> I considered that the increased number of robins might reflect
>>> more birders participating in these Christmas counts as well
>>> as an increase in birding skills. If there are more skillful
>>> birders involved in these counts I would expect a similar
>>> increase in the counts of other species. So I looked at the
>>> counts reported by the Bloomington CBC for the black-capped
>>> chickadee, blue jay and dark-eyed junco. I didn't find any
>>> trends or long term changes in the number of these species.
>>> Therefore, I'm convinced that the increased number of winter
>>> robins is real.
>>> I didn't attempt to see if there is a link between the increasein the
>>> number of robins counted and weather/climate.
>>> That leaves a question in my mind. Are the larger counts just
>>> a reflection that the Twin Cities population of robins has
>>> increased but the same proportion of that population is
>>> overwintering as in the past or have the overwintering habits
>>> of the robins changed?
>>> The CBC data speaks only to the presence of robins in December.
>>> Maybe the only change is when the robins migrate to warmer
>>> regions. Maybe if we had many years of counts for January and
>>> early February we would find that the number of robins in
>>> those months hasn't changed much over the years. As Manley
>>> Olson pointed out, once the robins exhaust the availability of
>>> crab apples, perhaps they head south and are now just as
>>> uncommon in January and February as they were back in the
>>> 1950s through 1980s.
>>> Val Landwehr
>>> Minneapolis
>>>
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>
>
> --
> Jason M. Frank
> Ortonville Public Library
> Founder & Vice President
> Luddite Ornithologists League (LOL)
> Big Stone County, Minnesota
>
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