[CT Birds] Calcium in Blue Jay diet

Kathy Van Der Aue kathyvda at gmail.com
Mon Mar 14 12:43:04 EDT 2016


I found the following abstract of the article David Spector referenced, in
case anyone is interested.  Passerines don't store calcium for egg-laying,
according to this, which must be why they crave it at this time of year.

"During the breeding season birds need increased amounts of dietary calcium
during egg laying and nestling rearing. Passerines acquire calcium shortly
before and during laying and do not store calcium for egg formation. Many
passerines need to cat extraneous calcium in the form of snail shells or
calcareous grit to acquire the element. However, very little is known about
variation in the dependency of birds on extraneous calcium, and where this
calcium is acquired. Using reports from volunteers who provided extraneous
calcium sources at feeder sites across North America we documented that (1)
the use of extraneous calcium varied during the breeding season; (2) the
location in which species preferentially took the calcium varied with
typicalfeeding location, aside from swallows which, somewhat surprisingly,
favored calcium offered on the ground; (3) Brown-headed Cowbirds (Molothrus
ater)did not visit calcium sites more often than other blackbirds; (4)
calcium use varied among species with thrushes, wrens, and woodpeckers
taking calcium only rarely, and swallows, pigeons, and corvids taking
calcium frequently. The most surprising result perhaps was the very high
frequency of calcium use in jays; Blue Jays (Cyanocitta cristata) may hoard
calcium in the fall."


Kathy Van Der Aue
Southport, Connecticut
Visit my Blog at http://naturaliststable.wordpress.com

On Sun, Mar 13, 2016 at 10:23 PM, Spector, David (Biology) via CTBirds <
ctbirds at lists.ctbirding.org> wrote:

> One study* found that indeed Blue Jays took supplemental calcium sources
> at bird feeders to a much greater extent than did other birds.  The reason
> for this apparent need for calcium by Blue Jays is not clear; I wonder if
> it has something to do with the chemistry of an acorn diet high in tannins.
>
> I have doubts as to whether providing Blue Jays with eggshells cuts down
> on their predation on the eggs of other birds; it could have the reverse
> effect if the supplements increase survival and reproduction of Blue Jays.
> Determining the effect, if any, would not be easy.
>
> David Spector
> Belchertown, Massachusetts
>
>
> *Dhondt, A. A. and W. M. Hochachka. 2001. Variations in calcium use by
> birds during the breeding season. Condor 103(3):592-598.
>
>
> ________________________________________
> From: CTBirds [ctbirds-bounces at lists.ctbirding.org] on behalf of Kathy
> Van Der Aue via CTBirds [ctbirds at lists.ctbirding.org]
> Sent: Sunday, March 13, 2016 9:54 PM
> To: Sue Lavallee; List CT Birds
> Subject: Re: [CT Birds] They're Coming!!
>
> I should have mentioned that I do microwave them, although only until the
> insides boil, about 45 seconds.  I particularly like the fact the Bluejays
> get them as I think they may take other birds eggs for the calcium and the
> eggshells may cut down on that.  They may have a greater need for calcium
> than other birds, but I have absolutely no science to back this up.  They
> are the prime customers for my eggshells though.
>
>
> Kathy Van Der Aue
> Southport, Connecticut
> Visit my Blog at http://naturaliststable.wordpress.com
>
> On Sun, Mar 13, 2016 at 7:31 AM, Sue Lavallee <suelavallee at charter.net>
> wrote:
>
> > HI Kathy,
> > Thanks for sharing the hbird map!  The earliest I've ever seen one in my
> > Canterbury yard is April 15th, although I put my 5 feeders out a week
> > before
> > that just in case.
> > I put eggshells in my compost pile for the calcium that they contain but
> > more often than not, Blue Jays make off with them. If you do put
> eggshells
> > out for the birds or in your compost pile, please be sure to sterilize
> them
> > first. Unsterilized egg shells may contain harmful Salmonella bacteria.
> I
> > put them on a plate in the microwave for 2 minutes just to cook any
> > leftover
> > egg whites.
> > Best!
> > Sue
> >
> > Sue Lavallee
> > Regional Sales Manager
> > Coast of Maine Organic Products, Inc.
> >
> > Cell 860-884-0611
> > Local phone / fax  860-546-6517
> > suel at coastofmaine.com
> >
> > 145 Newbury Street, Portland  ME  04101
> > 800-345-9315 ext. 107    Fax 207-879-0554
> > www.coastofmaine.com
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: CTBirds [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of
> > Kathy Van Der Aue via CTBirds
> > Sent: Saturday, March 12, 2016 6:44 PM
> > To: List CT Birds
> > Subject: [CT Birds] They're Coming!!
> >
> > http://www.hummingbirds.net/map.html
> >
> > Another note, put out those eggshells.  Mine are going like hotcakes!
> >
> >
> > Kathy Van Der Aue
> > Southport, Connecticut
> > Visit my Blog at http://naturaliststable.wordpress.com
> > _______________________________________________
> > This list is provided by the Connecticut Ornithological Association (COA)
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> >
> >
> >
> _______________________________________________
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>
> _______________________________________________
> This list is provided by the Connecticut Ornithological Association (COA)
> for the discussion of birds and birding in Connecticut.
> For subscription information visit
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