Are egg shells really necessary?

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ron20m
Posts: 446
Joined: Sat Jul 03, 2004 3:01 pm
Location: Oklahoma/Norman

I've been saving egg shells and putting them out because I saw it suggested here. But since most of the insects they feed on have exoskeletons why would they need extra calcium?
Robbo
Posts: 623
Joined: Tue Jun 09, 2009 2:53 pm
Location: Leduc, Alberta, Canada.

For egg laying, Oyster shells good too. All the songbirds seem to nibble on them at the feeder.
2009. 98 eggs, 66 hatch, 61 fledged.
2010. 114 eggs, 89 hatch,70 fledged.
2011. 96 eggs. 80 hatch,68 fledged.Heavy Merlin preditation.
2012. 89 eggs. 56 hatch, good fledge. Guards installed. Merlin not sighted at houses.
2013. First Egg May 24, first Baby June 13.
2014. successful.
2015. successful.
2016. Martin's population decline, suspect new housing in the neighborhood. Merlin eating well also!
2017.Population explosion :grin: . first egg May 25 in a BO-11
2018. Population stable.
Matt F.
Posts: 3894
Joined: Mon Feb 28, 2005 9:48 am
Location: Houston, TX

Hi Ron.
From what I've read, the exoskeletons of the insects the Martins eat, maybe void of any traceable levels calcium.
Eggs shells also provide a grit-like service, in the digestion process.
http://purplemartin.org/update/Eggshells.html
Ed Svetich-WI
Posts: 797
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.

For those of you who keep back issues of the Purple Martin Update, I suggest that you read the article in Vol.15(2) titled"Calcium Supplementation and Purple Martin Reproduction:..."by James R. Hill lll of the PMCA and Scott Rush of the University of Georgia. I do not know if the article is available on the PMCA website.

Quoting from the article, "Even if birds have enough calcium in their bodies for egg production,environmental factors can cause defects or, during breeding, improper development of the egg." They studied the collected data from purple martin landlords for over 2500 nests. "From the data. we were able to identify the number of eggs laid by, and the hatching success of,Purple Martins within the Eastern United States from 1995 to0 2000". The authors found"that provisioning supplemental calcium for Purple Martins leads to significant increases in both the number of eggs laid and the number of young hatched.Additionally, we found that the reproductive success was much greater among martin nests where calcium was provided in the form of crushed oyster shell as compared to those where crushed eggshell was provided.(emphasis mine).

The topic of calcium needs and supply is frequently raised here on the Forum.Unless these findings have been disproved, I suggest that we would be doing a service to the species by providing an ample supply of oyster shell during the period that the Purple Martin is breeding. Perhaps the PMCA can affirm the early work of these authors and put the question to bed(or nest).

I find the oyster shells to be convenient, inexpensive at about $10/50#, free of potential disease organisms and readily accepted by not only my martins but every bird in the area.

Ed
ron20m
Posts: 446
Joined: Sat Jul 03, 2004 3:01 pm
Location: Oklahoma/Norman

Thanks Ed very convincing
DebA
Posts: 1941
Joined: Tue May 04, 2010 7:43 am
Location: Pratt County/Kansas
Martin Colony History: Start 2009 with one pair. Upgraded from S&K houses to two Trendsetter 12's with gourds beneath in 2013. I have experienced job, pet, and parental losses since '13. The Purple Martins lift my spirits and remind me how life continues forward by flying their little selves from Brazil back to my yard. As one forum person once told me, chin up DebA, look at the martins. Danger all around but yet they soar in the sky without a care in the world.

I have a question. When do you offer the shells? Anytime? When nest building starts? When green leaves are brought in? I've done it when nest building but wonder if there is a benefit to do so now since my birds have paired up. No nests have started here.
Deb
PMCA MEMBER
Pratt County, Kansas
2016 34 PAIR
2015 27 PAIR
2014 23 PAIR
2013 13 PAIR
2012 6 PAIR
2011 4 PAIR
2010 2 PAIR
2009 1 PAIR
pmcharter1
Posts: 110
Joined: Tue Apr 03, 2012 2:59 pm
Location: iowa/madrid

i offer egg shells thru nesting, and summer, added calcium. now as they are migrating in the midwest, are wheather has been horrible, rain , cold temps, ect., i offer them scrambled eggs in their feeder trays as there are no insects for them, they love them, they need the noutrition, feed them, as they will remember it yrs to come.
pm charter1
lynnh
Posts: 389
Joined: Thu Jun 28, 2007 7:07 am
Location: Iowa, New Sharon

I use oyster shells only.Egg shells are such a pain anyway...Lynn.
2007 2 pair 8 fledged
2008 4 pair 18 fledged
2009 21 pair 87 fledged
2010 44 pair 174 fledged
2011 68 pair 244 fledged
2012 82 pair 364 fledged
2013 82 pair 359 fledged
2014 86 pair 415 fledged
2015 101 pair 427 fledged
Dave Duit
Posts: 1687
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 www.iamartin.org and join.

After I started using eggs shells and oyster shell years ago I saw an noticeable increase in clutch sizes and an increase in successful fledge rate.
Mite control, heat venting, predator protection and additional feeding during bad weather add up to success.
DebA
Posts: 1941
Joined: Tue May 04, 2010 7:43 am
Location: Pratt County/Kansas
Martin Colony History: Start 2009 with one pair. Upgraded from S&K houses to two Trendsetter 12's with gourds beneath in 2013. I have experienced job, pet, and parental losses since '13. The Purple Martins lift my spirits and remind me how life continues forward by flying their little selves from Brazil back to my yard. As one forum person once told me, chin up DebA, look at the martins. Danger all around but yet they soar in the sky without a care in the world.

I first used them last year and noticed my egg shells seemed thicker, less translucent. My question is should I go ahead and offer...mine haven't started nest building yet.

I started to type we haven't started nest building. Like I am out there doing it too. I do incorporate myself into their lives!

Deb
PMCA MEMBER
Pratt County, Kansas
2016 34 PAIR
2015 27 PAIR
2014 23 PAIR
2013 13 PAIR
2012 6 PAIR
2011 4 PAIR
2010 2 PAIR
2009 1 PAIR
pmcharter1
Posts: 110
Joined: Tue Apr 03, 2012 2:59 pm
Location: iowa/madrid

again, its a prefrence, i offer egg shells, my local restaraunt saves them for me, a good resource, i use them before they start nesting in feeding trays, it seems to help the clutch,( larger) more calicium the better.provide it, its like this spring, our migrationhas been cold, rainy, ect. i use scrambled eggs on feeders, and rooms, as no insects around. the martins dont forget the hand that feeds them--- so to speak, remember that, its true!
pm
Ed Svetich-WI
Posts: 797
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 have not seen this question posed yet this year. Thought I would revisit this instead of going over this again from the beginning.

Ed
Glynn B - LA
Posts: 322
Joined: Fri Feb 03, 2012 3:59 pm
Location: Louisiana West Monroe

Bet most, like me, didn't realize mealworms were calcium depleting.

Information from Sialis

http://www.sialis.org/calcium.htm#cal
2019 26 pair 116 fledged
2018 20 pair 76 fledged
2017 19 pair 82 fledged
2016 13 pair 48 fledged
2015 3 pair 13 fledged
2014 1 pair 4 fledged
2013 2 pair 6 fledged
2012 0 pair
2011 0 pair

I don’t have the perfect site. One open flyway with trees within 80 ft. I do have a small pond they utilize during the heat of Summer. (2017) HEAVY HAWK PREDATION
Ed Svetich-WI
Posts: 797
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.

The article specifically references feeding nestlings with mealworms. In this situation, there may be an issue with the quantity fed a nestling at the precise time that bone development is critical.In some wild birds, such as bluebirds, mealworms are promoted as an attractant and may cause issues with depleted calcium if they are then fed heavily to nestlings. It is something to consider.

I may be wrong, but martins are infrequently fed mealworms at a time when nestlings are present. Thus calcium depletion should be a moot point. At any rate, it emphasizes the importance of supplemental calcium for our martins. The best source being crushed oyster shell, according to the research provided in my earlier post.

Ed
pmcharter1
Posts: 110
Joined: Tue Apr 03, 2012 2:59 pm
Location: iowa/madrid

ED,
Last yr was unusal for Iowa, we had snow in late march, cold temps, in april.The birds made their trip, but you could tell they were worn out and ragged. with the cold and no insects to eat, i supplelmented scrambled eggs, placed them in front of their porches, , with egg shells.for calcium, nourishment, they had a long flight.Lucky for me i had nesting matatieral in place, but i still lost 4 pairs, they were to worn down, i even brought a pair in my house in nesting boxes, as they would have died to, we had temps in the 20s- 30s, , they flew thru the worst, to come home to the worst. My two i nested made it, , others made it, but my colony will be cut in half this year i know.
but as my scouts started coming back, as ragged as they looked, it was to cold for any insects to be found for them, as for meal worms, they may have worked, but it takes a second to microwave two eggs in a bowl, mix them up til there fluffy, , mash them in peices and feed them. as for the egg shells, i rinse the halves, place them on a cookie sheet in the oven for like 150 , for 15 minutes, til dry, crush them, they love them, i even do this thruout the summer in a feeder, they enjoy them, they wont forget the hands that feed them! good luck
pm charter 1
mikeinkaty
Posts: 28
Joined: Sun Mar 23, 2014 9:54 am
Location: TX/Katy

Being raised on a farm I know that chickens will lay soft shell eggs If they don't get enough calcium. I imagine the same thing would hold true for any bird. For chickens, mom always bought grit made from oyster shells.

As well as providing calcium the oyster grit would enable the chickens to grind up food in their gizzard. That grit though would probably be to big for PM's unless you pounded it up finer.

Mike
Katy TX
Steve Martin
Posts: 68
Joined: Sun Feb 23, 2014 9:38 am
Location: Tx/Bastrop

pmcharter1 wrote:i even brought a pair in my house in nesting boxes, as they would have died to, we had temps in the 20s- 30s,
So the birds were inside of a nesting box and the box was inside your house. Was the nesting box a gourd? was it a multi unit birdhouse? Did you shut up the nesting box so they could not get out when you were moving it? Did the birds freak out when you were moving around there "house" while they were still inside?
pmcharter1
Posts: 110
Joined: Tue Apr 03, 2012 2:59 pm
Location: iowa/madrid

Steve,
first, i want you to know how deep my passion runs for these birds., ive had colonies for yrs, when you enjoy somthing about their morning song, and how magestic they are , and how far they fly to come home, if they are able to make the effort to come back, - to your home, you take care of them, and you do with housing, ect
It was cold last spring in ia, i found 4 pairs, dead, in my house, with proper bedding ect. , they were-so weak, supplimental feeding never worked. a week later two more showed up, not in good shape., so weak, they couldnt fly, i lowered the house and scraped off the snow, i have trios.,
i placed them in 4x6 pine rooms, with lids, and caps, i put pine straw in there, and went outside lowered my trio, they were so weak, i used gloves to place them in the house, brought them inside, in my hunting room, and waited the night out, feed them scrammbled eggs, it took a day or two till they come out of it, they did not freak, the window was there, got light, and dark, , so they wernt in the dark24-7, as far as my den , its dowstairs, where i wanted them, ( less traffic), they were fine , slept during the night, got more active during the day when they got thier strenght back, when they got better after 2 days, i lowered my trio, opened a room, they went in,i used cotton gloves. i still supplilmental fed for two weeks as our wheather was cold there were 2, that made itI have two trios 12 room houses, 80 percent in both, for yrs, even expanded to gaurds, i ended with only 4 pairs that made it, one pair was the one i saved.
my trios were maxed out, so i fabricated my own pole, 10 gourd, design, which i can add on , now, im wondering if ill fill my trios.
Good luck to you, hope your colony is great.
your on our website, Dave duit and i started - with help of others to create the first Purple Martin chapter , in Iowa, Dave has a slide show at the fair, and we are working hard to promote our birds!, in iowa, we have a pot luck,yearly thats posted on this site, and have had people attend from surrounding states, we are excited to educate others about the Purple Martin, housing, mite control, feeding ect.
this site has moderators for some counties, in iowa, your questions can be directed to this site, or me pm charter 1 if i can help- from this site
Ed Svetich-WI
Posts: 797
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.

Seems appropriate to bring this discussion back.
lynnh
Posts: 389
Joined: Thu Jun 28, 2007 7:07 am
Location: Iowa, New Sharon

Thanks for bumping this thread back up, Ed.

I dont understand why so many folks insist on eggshells when oyster shells
are better for the birds not to mention easier.

:roll: :roll:
2007 2 pair 8 fledged
2008 4 pair 18 fledged
2009 21 pair 87 fledged
2010 44 pair 174 fledged
2011 68 pair 244 fledged
2012 82 pair 364 fledged
2013 82 pair 359 fledged
2014 86 pair 415 fledged
2015 101 pair 427 fledged
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