Crushed Oyster Shells ??

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Hanover Bill
Posts: 601
Joined: Thu May 14, 2009 3:10 pm
Location: Pennsylvania/Hanover Township
Martin Colony History: 2009 & 10 - 0
2011 & 12 - Visitors
2013 - 2 pr. fledged 9
2014 - 3 pr. fledged 13
2015 - 7 pr. fledged 27
2016 - 15 pr. fledged 72

I don't eat a lot of eggs, so thus I am short on egg shells to place on the bed & breakfast for the Martins. I picked up some crushed oyster shells the other day, but they use the word "crushed" pretty liberally. They are quite large pieces. I'm not sure if the Martins will be able to ingest them or not. Is there an easy way to further crush these into smaller pieces or are finer crushed ones available for sale somewhere?

Hanover Bill.
2009 & 10 - 0
2011 & 12 - Visitors
2013 - 2 pr. fledged 9
2014 - 3 pr. fledged 13
2015 - 7 pr. fledged 27
2016 - 15 pr. fledged 72
Posts: 47
Joined: Mon May 04, 2020 5:13 pm
Location: Texas

You could put them in a cloth and gently whack with a hammer or use the smooth side of a meat tenderizer as a hammer. I made a platform feeder a week ago and placed it about 25 feet from our gourds. I put dried mealy worms on the platform, I've had some of them show interest but they haven't landed.
JJ Ranch
Texas Hill Country
Posts: 412
Joined: Wed Mar 16, 2016 9:17 pm
Location: Raymore, MO

I crushed the oyster shell with a hammer as well. Don't overdue it and make powder. :)
Ed Svetich-WI
Posts: 782
Joined: Tue Jan 13, 2004 10:05 pm
Location: Brooks, Wi (McGinnis Lake)
Martin Colony History: 24 Super and Excluder Gourds on two gourd racks, all SREH. Full occupancy. My philosophy is to maximize fledge % with existing cavities rather than adding gourds to grow colony, thus providing opportunities for new colony expansion. Fledge over 100 nestlings yearly from 24 gourds. Band nestlings in cooperation with state university. 2019 Adendum: Reduced colony size to 12 gourds to focus on more intensive management regimen.


I'm surprised. You must have seen my long thread on the advantages of oyster shell over egg shells in providing calcium for larger clutches of martins in the past several years.You can search it here on the Forum. I won't rehash the study here. Since most do not have access to whole oyster shells, a 50# bag of pullet or chick size oyster shell can be found for about $10 at most farm stores. I know Tractor Supply carries it. They also have it in smaller quantities. Just be sure it is oyster shells and not coral. The coral has a lot of dust.

Produce a lot of martins this year.

Thanks and God Bless our veterans.

Dave Duit
Posts: 1656
Joined: Tue Nov 25, 2003 2:02 pm
Location: Iowa / Nevada
Martin Colony History: In 2019, 54 pair with 218 fledged youngsters. 83 total compartments available, 58 Troyer Horizontal gourds and 4 modified trio metal house units, owl cages around all units. Martin educator and speaker. President of the Iowa Purple Martin Organization. Please visit and join.

Yep, the hammer and cloth do the trick. Also, I want to thank Ed for bringing the attention to the oyster shells and its benefits. I use a combo of oyster shells and egg shells.
Mite control, heat venting, predator protection and additional feeding during bad weather add up to success.
Posts: 41
Joined: Fri Apr 10, 2015 1:35 pm
Location: MN/Foley

....try sweet talking the cook at your local café/ 11am, she/he, will have saved you more eggshells than you can probably use......mrk
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