[CT Birds] Calcium in Blue Jay diet

Spector, David (Biology) spectord at ccsu.edu
Sun Mar 13 22:23:22 EDT 2016


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
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