EFFECTS OF SUPPLEMENTAL CALCIUM ON THE GROWTH RATE OF AN INSECTIVOROUS BIRD: THE PURPLE MARTIN (Progne subis)

Dave Duit · Fri Feb 22, 2019 3:43 pm

For those wanting in depth research of the purple martin. Good reading.
http://www.collectionscanada.gc.ca/obj/ ... q30537.pdf

Enjoy,
Dave Duit

C.C.Martins · Fri Feb 22, 2019 8:45 pm

Interesting! I think we all have found stange things in the cavities after seasons end. We live on the coast and find broken bits of shells left behind, the ones left are fairly large, almost half an inch long...too big to injest id imagine.
What i found most interesting was the early nestlings grew faster and left earlier than those of later clutches. Tough to take into account weather, drought, overabundance of rain, parasites, parent experience, etc, on chicks overall growth, but he specifically mentioned early arrival birds to me those are ASY. Makes you wonder if that plays a factor in the ASYs rush to get to prime breeding grounds they remember from seasons prior.
Thanks for sharing,
Tom

Spiderman · Sat Feb 23, 2019 10:30 am

I save my eggshells all year as well.

I know some people don't believe in it, but I feed mine a dozen egg shells a day once nesting is in full swing.

It is the only thing I have seen them react to so quickly. You must break them up into small pieces but they go Crazy over them. They will land around me and not let me get out of their way. They feed a lot of pieces to the Fledglings as well. It seems to be as important as insects at times.

Dave Duit · Tue Feb 26, 2019 2:10 pm

Good to see some people have read this research post. My martins readily take to egg shells and well as oyster shells. I think it is a great source of calcium and grit for digestion and growing strong shells. Thanks everyone.

Chris B · Tue Feb 26, 2019 5:27 pm

I have a limestone rock driveway and the birds like eating off it when egging, I think.

flyin-lowe · Tue Feb 26, 2019 7:39 pm

Some time last year I started a thread after seeing a lot of my Martins flying down into my neighbors fire pit. I wasn’t sure if they were dust bathing or not but noticed in the attached research they mentioned ash as a source, maybe they are consuming some ash??

Dave Duit · Wed Feb 27, 2019 4:04 pm

My best guess is as another source of grit. Instead of the ash, they may be going for charcoal bits. I'm not an expert and in no way should this be considered set in stone as 100% correct.

Badger · Thu Feb 28, 2019 1:25 pm

I feed egg shells to. I microwave mine. Is there a good way to keep eggshells all year until needed?

KathyF · Thu Feb 28, 2019 6:18 pm

Badger wrote: ↑
Thu Feb 28, 2019 1:25 pm
I feed egg shells to. I microwave mine. Is there a good way to keep eggshells all year until needed?

I bake mine at 225 deg. for 12-15 minutes. With all the recent problems with e.coli, etc., I decided to not take the risk that a microwave wouldn't kill the bacteria.
Then, I crush and store in a Ziploc freezer bag in my Freezer, so that no bacteria can get restarted if there is any left.

clivia98 · Thu Feb 28, 2019 9:06 pm

I have crushed oyster shells. Where can I put them for the birds. I remember a post suggesting to put eggshells and crushed oyster shells on the porches. Will that work? Or should I scatter them on the ground beneath the houses?

Dave Duit · Fri Mar 01, 2019 9:56 am

Hi clivia98,
You can spread the crushed egg shells or oyster shells on a raised platform near your colony, a shingled roof nearby or lastly on your driveway. Some people to the same for crickets and scrambled eggs for supplement feeding during cold wet days.

Dave Duit · Fri Mar 01, 2019 9:59 am

I do believe martins feel less secure if oyster/ eggs shells are scattered on the ground, due to ground predators,(cats, snakes, raccoons) and less chance to get away or exit from cooper and sharp shinned hawks attacks. I put mine on a raised platform feeding tray.

TheSmiths · Fri Mar 01, 2019 9:21 pm

clivia98 wrote: ↑
Thu Feb 28, 2019 9:06 pm
I have crushed oyster shells. Where can I put them for the birds. I remember a post suggesting to put eggshells and crushed oyster shells on the porches. Will that work? Or should I scatter them on the ground beneath the houses?

The PMCA store sells feeding trays — https://www.purplemartin.org/shop/58/su ... n-feeding/

We have the "Royal Wing 3-in-1 Platform Feeder" mounted from the bottom using the method shown below.

clivia98 · Fri Mar 01, 2019 9:42 pm

Thank you. Where did you buy it?

TheSmiths · Fri Mar 01, 2019 10:35 pm

clivia98 wrote: ↑
Fri Mar 01, 2019 9:42 pm
Thank you. Where did you buy it?

You're welcome. We picked up the feeder at Tractor Supply and the mounting supplies at Lowes in the electrical section. Menards also carries the same feeder under the brand name "Stokes".

Dave Duit · Mon Mar 04, 2019 9:27 am

Hi,
I built my own raised platform feeding tray using ideas of google images found on the internet.