Bluebird Eggs (Part 5)

In addition to Messages that have appeared in the Bluebird Mailing Lists on this topic, the following are on the Audubon Society of Omaha website:  Predators and Problems On The Bluebird Trail

From: Simon [mailto:simon"at"bowecho.com] |
Sent: Thursday, June 17, 2004 1:31 PM
RE: strange....

LOL I did make a little nest of some hay to provide a bumper from the sides of the box, and the floor... I e-mailed a lot of you privately about it, but I want to come clean here in public. ;-) I checked the box today, and there are still four lovely BB eggs in the new nest (I think one disappeared, but I am not sure, I don't handle the eggs unless I have to, so there may be one buried in my make-shift nest), and as I saw activity there last night, I am pretty sure that I did not run them off. I noticed a box not far from there with a nest in it that looks pretty much like a BB nest, but no one has used it in over a month. I wonder if that was her original nest, and she left for some reason. I'm glad if she did because she moved TO the house with the predator guard and the hole extender. "good thinking, mom!" I ALSO think that I have another pair nesting in another box... this would be my first time having two mothers in labor at the same time :-) I'm really getting excited. Thanks for the feedback. Theresa"at"BowEcho.com

From: Glenn Williams [mailto:glenwill"at"chilitech.net]
Sent: Saturday, June 19, 2004 12:25 AM
Subject: Pic of 2 day old EABL!

Sadly it appears that the 5th hatchling has had a problem, I held it in my palm and sensed no movement but I used my fingernail to chip, a large portion, more of the shell away and then put it back in the nest. I hope it is still alive. I guess I'll find out tomorrow.

From: Dick Stauffer
Sent: Monday, June 14, 2004 10:05 PM Subject: Unusual behavior

Hello Don: I have attached a picture ( Box 132 ) of a very early bluebird nest with some unusual behavior. Two eggs were remove from the nest cup and placed up on the edge of the nest. I had this happen in two boxes  (Box 8 &132) that had early nests. The box (132) in the picture had 5 eggs by May 12. The other box (8) had 2 eggs on April 28. Both of these nests failed, I believe that it was weather related. I have data loggers in both boxes. The picture shows the gray cable from the data logger to the nest cup. The other box (8) has had the logger removed, the logger shows that temperatures recorded in the nest cup were as low as 27F. I checked box 8 on the cold & snowy May days, the eggs were covered with snow. I still have the logger in 132 as the box has now been taken over by Tres, seems they built over the Mobl nest. Dick Stauffer

You might remember that I posted a few weeks ago that I had eggs in a nest-box with no nesting material in it. I added some hay to the nest-box, and carefully replaced the four eggs. I checked on the eggs between then and now, and noticed that one egg was off to the side. I think the female pushed this one away, but since she accepted the others, I didn't push it back. Today three baby bluebirds hatched! ...

I checked my bird book the other day, and noticed that when I moved here three years ago, I wrote in my bird book that there were no birds visible except for HOSPs…. I have a huge selection of birds now – probably 20 species. Just a little work makes a huge difference.

Theresa 

From: Dottie, Hickory Hollow, Brown County, Indiana [mailto:yumyumkatts "at"voyager.net]
Sent: Sunday, November 28, 2004 9:07 PM
Subject: Re: Strangely marked bluebird

I thought Barry [Whitney barryw"at"therock.mcg.edu] might come back on the List since his recent post but I haven't seen any posts from him since. I was hoping Dan would share his dwarf BB egg he had but he hasn't yet.   He had pixs of it at our BB club meeting.  He said he had e-mailed Keith about it and Keith said he had only seen a few dwarf BB eggs.  It was cute but strange.
Dottie, Hickory Hollow
  Brown County, Indiana

From: jwick "at"tds.net [mailto:jwick "at"tds.net]
Sent: Tuesday, November 30, 2004 12:26 AM
Re: Strangely marked bluebird

I have experienced only 1 dwarf bluebird egg in my 20+ years of monitoring nestboxes. I do have a photo of it! :) Ann Wick Black Earth, WI

Hi All, I have a question about egg laying. We have a nest that has 4 egg so far but this is what is strange...

One egg was laid on the 7th ..then 9th then.. 11th...then...13th

I thought they laid one a day period...they could drop one on the outside...but this is a bit odd isn't it?

We did have a couple days of terrible cold for us...and then we had one day of bad cold rain....can they stop laying like this?

Christy

Subject: RE: Egg Laying - Days
Date: Sun, 13 Mar 2005 14:30:30 -0600
From: Evelyn Cooper <emcooper"at"bayou.com>

Last year, I did have one female skip the second day and resumed the laying the third day. The weather was wretched. First time I witnessed that.

Evelyn

Subject: Re: Egg Laying - Days
Date: Sun, 13 Mar 2005 14:49:36 -0600
From: mrtony8 <mrtony8"at"cox.net>

not a problem at all. strange things happen in these boxes. i have seen them skip one or two days between eggs.
Phil Berry

Subject: Re: Egg Laying - Days
Date: Sun, 13 Mar 2005 12:55:39 -0800 (PST)
From: <bookfanaticef-bluebird"at"yahoo.com>

Christy,
Birds are highly variable in many ways. While bluebirds usually lay one egg a day, it may be that laying one egg every other day may be normal for your female. It doesn't seem as though she's delaying laying because of the weather, since she's been regular in the intervals, just that her cycle is slightly different from the "norm."

When you read things like "such-and-such bird lays 3-5 eggs, one every day until clutch is complete, etc" it is not an absolute. Such information is compiled from data collected by people over many nests for many years, and is more of an average than an absolute (of course the more data collected, the better such statements become). In nature, *nothing* is absolute--there is always some variance, sometimes a bit unexpected. Even if such anomolies have been noted, there is usually not enough space to list them all thoroughly, especially since most people are interested in what they would typically see for that species anyway. One "anomoly" I have often seen in reference to bluebird nesting though, is that sometimes they lay eggs that are white or partially white, rather than blue. Apparently, this is a more frequent occurrence than something like an unusual laying interval, and so merits mention.

On a similar note, I have spent a couple summers searching for & monitoring bird nests for scientific studies, and I know that what is published in some field guides and books does not always refer to the average seen everywhere--only in those places that species has previously been studied (and some species have been studied very little). For instance, Eastern Towhees are said to nest on the ground, with a cup in a slight depression in the ground (I think in both Peterson's Guide to Eastern Birds' Nests and in the Guide to North American Eggs, Nests, and Nestlings by Baicich & Harrison)--but in a scrubby south Florida pine flatwoods, we *never* found an EATO nest actually on the ground--they ranged from shin to waist height, nearly always in one species of small bush. Guess the birds didn't read the books!

Hope your eggs become fledglings soon!
Elizabeth Farley
Gainesville, FL

Subject: Re: Egg Laying - Days
Date: Mon, 14 Mar 2005 02:09:15 GMT
From: Maynard Sumner <m-r-sumner"at"juno.com>

Yes, the birds most of the time know what to do. In Michigan the cold can some times stop them for a week or more.

Maynard Sumner
Flint, MI

Keith Kridler Mt. Pleasant, Texas
There are quite a few volunteers working with Cornell this year installing
Temperature Data Loggers in nestboxes, one in with the eggs and one in the
top of the nestbox to monitor the exact temperature of the eggs and the heat
or cold inside the nestbox. This is the third year I think. They do have
some published data on this program already.

They are trying to see exactly what temperature range eggs in "wild bird"
nests can tolerate under "normal" conditions. You can tell almost to the
minute when the female is incubating the eggs and when she has left the
nest. Just because the female is inside the nestbox DOES NOT mean she is
incubating the eggs!

Texas A & M University TAMU had an excellent brochure on eggs that was also
available on line that gave optimum temperature, humidity and time required
to hatch out about 50 different species of birds from parakeets to
ostriches. It gave the effects of heat and cooling and high and low humidity
on the viability of the eggs. Most agriculture extension offices also have
USDA brochures on hatching out eggs. MOST research has been done with
domestic birds used commercially but temperature and humidity requirements
are almost identical from a parakeet to a chicken only the days required to
hatch the eggs vary. I believe optimum temperature was 99. something *F.
According to USDA brochures, bird Embryo's actually begin slowly forming in
the egg when the egg reaches 75*F or above in the core. It rapidly speeds up
forming as the temperature approaches 90*F.

Eggs can be held for several weeks under the right storage conditions. They
must be cool and humid. Egg shells are permeable and allow moisture to
escape from the time the egg is laid until it hatches. Weight five bluebird
eggs when laid, wait a week and weight them again and they will be lighter.
Wait another week and they are lighter still.

Freshly gathered eggs when boiled stick badly to the shell. For easily
peeled boiled eggs buy and date your eggs, store them in the refrigerator
for two weeks then boil them, they will lose enough moisture to peel easily.

They actually have charts for chicken eggs and for optimum hatching numbers
out of an incubator they know exactly the percentage of weight these eggs
should be losing each week. If these eggs are incubated a couple of degrees
too cold and the humidity is too low baby chicks will slightly dehydrate and
stick to the egg shells and not be able to peck out of the shell because
they cannot rotate all the way around inside the egg shell. If the eggs are
kept too warm and the humidity is too high the embryo's form faster, don't
give off enough moisture and a higher percentage of the young birds hatch
out with poor muscle quality and too high a body weight percentage of water.
Some are actually too big to rotate all the way around inside the egg shell
to break out.

American's consume about 6 billion chicken eggs a month. Hens average laying
about 23 eggs every 30 days. Do the math to see how many hens are in cages
laying eggs for you today. It takes three men or women now to feed, water
and gather the eggs, wash the eggs and crate them up in cartons from 300,000
laying hens. They gather eggs 365 days a year and are responsible for
getting the egg into the refrigerated trucks. They work for minimum wage and
receive no overtime pay no matter how many hours a week they work.

Many birds hatch out with birth defects and the adult birds often will
remove them within the first few hours or days of hatching. People cull baby
chicks coming out of incubators.

Baby chickens and turkeys are now all given a combo vaccination shot before
going to the growers farms. A good woman can vaccinate thousands of chicks a
day. They often vaccinate one of their own fingers so vaccines must be safe
for humans. Many of the newer untested vaccines are applied to the egg
shells before they go in the incubator for 21 days as a "patch". This means
that any pesticide, herbicide, fungicide, oil ETC. that get on the females
brood patch or belly feathers from the bird bath or sewer lines or oily,
anti-freeze tainted puddle in a parking lot, can and will be carried by a
brooding female that bathes in the puddle back to her nest and applies this
to her eggs.

Soap cuts oils on a birds feathers. Soap when it dries on an egg shell will
reduce the permeability of the shell limiting the amount of air and moisture
entering and leaving the embryo. To kill Canadian Geese eggs you remove the
eggs from the nest and roll the eggs in vegetable oil to apply a super thin
layer of this oil to the shell. The oil plugs up the pores in the egg shell
and the embryo smothers before it has a chance to form.

Our government when they want to kill huge flocks of birds will wait until a
very cold night and then spray the nuisance flocks of birds on their roosts
right after dark with soapy water. Soap removes the oils or really allows
the water to soak the birds feathers reducing the amount of insulation
quality of the feathers. Overnight many of the birds will freeze to death.

For those wanting to keep the House Sparrow or Starling eggs from hatching
in their nestboxes you could actually see if applying hand soap, dish soap,
septic tank water, diluted round up or what ever you or your neighbors
commonly use in your yards, gardens or kitchen to brush on the egg shells of
these House Sparrows. 80% of them should hatch out normally, you could test
to see what reduces the viability of the eggs. (Of course suggesting this
type "research" is mostly tongue in cheek for this would have to be done
with collected House Sparrow eggs that are placed inside an incubator to
control variables! Also Cornell would boot me off the list for telling you
to go out and do this!!!:-))

Back in the 60's or 70's researchers subjected House Wren eggs and young
baby wrens to heat and that is how they published that 104*F for X number of
hours (I think four hours) was lethal to "eggs and baby birds". When the
core temperature of an "egg" reaches 107*F for 20 minutes or so irreversible
nerve damage is inflicted on the developing embryo and it will not survive
to become an adult bird. This is similar to humans who cannot tolerate a
core temperature of 109*F without suffering brain damage and or nerve
damage. KK

Keith Kridler Mt. Pleasant, Texas
About this time of year people post to the list about "white streaks" on
their bluebird eggs.

Freshly laid eggs early in the year OFTEN have blood stains on the egg
shells. That is an awfully large object to pass from a small bird, I hear
kidney stones are REALLY bad! But anyway very often blood vessels break and
the egg shell ends up stained.

White streaks: Birds feces and urine pass through the same pathway as do
their eggs. Freshly laid eggs often are streaked with the white or urine
from the bird. Freshly laid eggs are "eggshell" dull sheen. They can nearly
be seen through before the blood vessels begin forming. You can easily see
the air sack in the large end of most bluebird eggs.

The longer the female incubates the eggs, the more she turns them, the more
she turns them the cleaner the eggs get wearing off the urine or blood
stains from the egg shells. You can almost tell the age of the eggs by how
shiny the egg is becoming. As the embryo forms inside the egg the egg will
become harder to see through and the air sack will slowly get squeezed down
to nothing or about nothing and the baby will depend on outside air
penetrating the egg shell more and more.

Counting newborn birds is fairly easy, whistle or make a squeaking noise and
the young birds will struggle to open their mouths to beg for food. Normally
you can get five out of six to "beg for food".

Saturday at a cemetery a lady was cleaning a plot and she walked over to see
a nest full of "baby bluebirds", when I whistled all five baby birds
wriggled around getting untangled from each other and tiny yellow rimmed
bird mouths begged for food. They blindly, weakly waved on tiny threads of
pink necks like tall stemmed flowers blowing in the wind.

After a few seconds one by one they dropped their heads from this exhausting
task! Again I sharply whistled and once again, quicker this time tiny heads
shot up and tiny squeaks came begging out of this "clump" that looked more
like fishing worms than baby birds. This older lady was totally amazed!

I have been blessed with watching more than forty generations of bluebirds
"Beg" for food. We tend to forget that these birds have evolved over millions of generations to be here and give modern day humans the Peace and Joy that only the Bluebird of Happiness can bring.

Me thinks folks need to back off and go sit and enjoy these birds more, they need to share a nest full of eggs and baby birds with old folks and young alike more often. Peace and Joy to all who will listen:-)) KK

We might be missing an egg from one nest (EABL). Scott checked it out (we'll double check on the count tomorrow) but couldn't find any egg shells or any other signs of predation, including any obvious human disturbance. If the egg cracked, or the female otherwise didn't think the egg was "fit", might she have eaten the egg/shell? just removed it from the nest? In case it matters, the eggs have been incubating for
12 days today.

Kathy Haines
Central Ohio

From: Laurel Baty [mailto:laurelbaty"at"comcast.net]
Sent: Sunday, May 08, 2005 8:54 PM
Subject: Candling Bluebird eggs

Can anyone tell me what to look for in candling a bluebird egg? I have a pair of bluebirds that laid 5 eggs. The first egg was destroyed by a house sparrow--I caught him coming out of the box. I trapped several sparrows including the one that destroyed the egg and the bluebirds laid four more eggs. The female has been incubating for 22 days now and the eggs have not hatched. I took out an egg today and candled it--I saw nothing in it but there were 2 distinct layers, an upper dark layer and a lower light layer. The female continues to incubate and spends very long periods in the box.
I once had a bluebird incubate a clutch for 60 days (it was her 3rd clutch). Should I remove the eggs, even though the female is actively incubating?

Thanks
Laurel in Maryland

My favorite website on candling eggs is http://www.homestead.com/shilala/candling.html because there are some really good pictures.

Good job trapping the sparrows, clearly the bluebirds appreciated it.

Weather here has been cold and rainy so there has been some delay in hatching, don’t know about your way. Sometimes the female doesn’t start incubating right away when weather is a factor. I assume you are counting the 12-14 typical days from the date the LAST egg was laid.

I think I’d wait maybe 10-14 days after when they were expected to hatch before removing eggs, just in case. It’s still early in the season, so they’d probably try again.

Bet from CT

Hi All, I had a new to be Monitor call today and report that in her small
Tampa FL area yard, that she has been seeing Bluebirds. She has two boxes
up, but she never thought she would get BBs, but they did use the box.

The poles are 8 ft up and too close to feeders, and she has never monitored
them. She she did go look after they used one box and then mover 20' over
to the other. Then they left there too. She looked and in the second box
was a nest and One While egg, but that egg only had half a shell but the
whole membrane.

She then went to the first box and found the same thing...one white egg full
membrane in tack but only a half shell.

So what do ya'll think... is this going to be something the Mom outgrows or
does she have an egg making problem that will never get better?

Christy

Have any of you ever seen a Bluebird remove the egg shells and drop them on the ground by the nestbox? There is a discussion going on with another forum and they have stated that the female throws them out the nestbox and on the ground.

From what I have read and experienced, they either eat them or carry them a distance from the nestbox. The carry the fecal sacs a good ways from the nestbox also as a safety precaution against predators. One person insisted that Bluebirds do throw them out of the nestbox as a common way of discarding them.

What do you think?

Evelyn Cooper

I'm no expert, like a lot of you are...but I have NEVER seen bluebird egg shells anywhere, let alone, right outside the nest box. That has been my observation.

Cristy
Lenexa, KS

I have witnessed the mama bb removing the egg shells and carrying them away.
Elaine Hebert
Lake Charles, La.

Yes, I have seen the Bluebirds remove the eggsshells and carry them a long ways away. I had Bluebirds hatch out July 19 and July 20 and no eggsshells are under the box.

Maynard Sumner
Flint, MI

I've never seen the bluebirds actually carrying the eggshells off, but I've never found them in the nest, either. The only time I've found shells by the nestbox is when the HOWR attacked the nest. I believe they carry them a distance away, as they do the fecal sacs, to prevent predators from locating the nest.

Barbara, in Cloverdale, CA

From: Dottie, Hickory Hollow, Brown County, Indiana [mailto:yumyumkatts"at"voyager.net]
Sent: Sunday, July 31, 2005 11:57 AM
Subject: Bluebird Eggshells

We watched a tape at out BB club meeting this month of mom BB doing both. Removing and eating the BB eggshells. Mostly eating.

Dottie, Hickory Hollow
Brown County, Indiana

Bluebirds carry the eggshells (as they do fecal sacs) far away from the nestbox so as not to alert predators to the nestlings. I've not ever seen egg shells deposited under or near a nesting site (for any species of songbird, actually).

Diane Seward
Potomac, MD

Ditto here. I am no expert either and have only been trail monitor for 4 years, but have never seen discarded EABL egg shells under box. I was unfortunate enough to see some smashed discarded ones under a box once, but these contained yolk etc. from attempted HOSP takeover.

I would imagine that the EABL might accidentally drop a couple near the box while taking them farther out, but I have never observed this, so I doubt it is common if it occurs. Good nestbox hygiene for safety of young would imply taking egg shells and fecal material a distance from the box so predators will not be drawn to it I would think.

Paula Z
Powell (Central) Ohio

From: KimMarie Markel [mailto:auroramn"at"verizon.net]
Sent: Saturday, July 23, 2005 9:16 AM
Subject: Update on Dented/Damaged Eggs

My friend Jackie in North Carolina is the person who had the dented/damaged eggs (caused by a lawnmower hitting the nestbox pole). She's been writing to me and keeping me up to date on the box, here's an update:
the eggs (four) were initially damaged on the 17th, parents removed three of them on the 19th and the female left the nest/stopped incubating the remaining egg. The male stayed in the yard, calling for the female for two days, but no sign of her. Jackie checked the box on the 21st, the last egg was cold and definitely cracked so she removed it and some of the nesting material. Yesterday (the 22nd) the female came back (to lot's of wing flapping and singing from the male *grin*) and when she checked the box this morning she found material added, the nest tidied up and a new cup formed. I don't know if they'll renest, but I've learned that you never say never.

She and I would like to thank everyone for their comments and advice. Hubby is no longer allowed to mow that close to the box :)

kimmarie :)
Buffalo/Varysburg, Western NY

I have a nest finished three days ago and the pair dive bomb me like crazy.
I am hoping she will lay. If she does lay, it will be up in late August for
fledging. I have 11 others with eggs and babies hatching every day.

Evelyn Cooper
Delhi, LA

In my 2nd year of Bluebirding, my husband was mowing with our tractor and bushhog. His seat --which was a new one but defective and unknown to us--almost threw him out causing him to lose control of the tractor. The bushhog hit my BB box with five babies and destroyed everything.

Mom and pop BB flew around the yard looking for their babies which was a sad thing for us to see. However, we thanked God that my husband wasn't killed or injured.

We put up a new pole and box the next day and mom and pop BB nested right away and had another family which fledged AOK.

Dottie, Hickory Hollow
Brown County, Indiana

From: Gretchen Hughes [mailto:lghughes"at" joink.com ]
Sent: Saturday, July 23, 2005 1:04 PM
Subject: crazy blues

Hi all,
Just a crazy story--on one of my trails, I had a box with 12 day old babies, and the female was found dead in the box, I told the folks where the box is located, that the male would feed and fledge the babies. At the time of fledging, the people were in the yard with their cell phone reporting what was going on. We cleaned the box out and with in a week, papa blue had a new Mrs.. and a full nest with 4 eggs. A couple days later, there was another nest built over the 4 eggs, with 2 eggs. So I carefully removed the 4 eggs from the lower nest and put them in the upper nest with the 2 eggs. She evidently didn't like that so she built another nest on top and laid 4 eggs. those she sat on and hatched 3 of them. This was a new experience for me. Had never seen anything like it in 9 yrs of monitoring.(I do 243 boxes) I have had a nest built on top of the old one, between weekly monitoring, but this was so funny, I just had to share.
Loren Hughes-Pres. East Central IL Bluebird Society
1234 Tucker Beach Rd
Paris, IL

From: Pamela Ford [mailto:jpford"at"comcast.net]
Sent: Sunday, April 09, 2006 1:23 PM
Subject: First egg in backyard box in MD

The first egg in my backyard boxes was laid yesterday, April 8, 2006. There is a second one today, and now that there are two side by side, I can see that one of the eggs is significantly larger than the other. I haven’t seen this before. It is not likely to be a different female as there would be three eggs in the box today. Both eggs are the same blue shade.

Have anyone seen this before?
Pam in Harford County, Maryland

From: Amy Louise Marr [mailto:MARR_AMY_LOUISE"at"Lilly.com]
Sent: Tuesday, April 11, 2006 7:11 AM
Subject: Re: The 3 abandoned eggs & what I'm doing...

Hi
I have worked with chickens and chicken eggs, and wanted to comment on the egg storage and attempted fostering of the abandoned eggs. Broiler eggs are routinely stored for short durations prior to setting. However, extended periods of storage will result in dramatic decreases in % hatch.
Here is an excerpt from a U of Florida cooperative extension paper. Consider that these eggs were stored under ideal controlled temp and humidity conditions.

If your eggs have been stored several weeks, unfortunately I don't think they're going to hatch.

I would suggest removing the fostered eggs from the new nests. This will reduce the chance of having one of them exploding ( it does happen!) and spreading bacteria. Overall, removing the old eggs will give the fresh eggs a better chance....

Management of Hatching Eggs and Broiler Performance
G. D. Butcher, DVM, Ph.D., Amir H. Nilipour, Ph.D.

University of Florida Extension

Duration of storage of hatching eggs can have a dramatic impact on percent hatchability. The results of two large studies, conducted by the authors, demonstrated that fertile eggs held under recommended conditions of temperature and humidity completely failed to hatch when held in storage for more than 25 days. Even after 7 days storage, a significant reduction in hatchability was noted (Table 1). To achieve maximum percent hatch, the authors recommend to store eggs not more than 3 days in the egg room and maintain the egg holding room at a temperature of 65°F and relative humidity (RH%) of approximately 78%. These temperatures and RH% settings need to be adjusted when egg storage periods are prolonged in an effort to conserve the internal integrity of the eggs. As a rule of thumb, as the egg storage time increases, storage room temperature should be decreased and the relative humidity increased to prevent dehydration.

Table 1. The effect of egg storage on % of hatchability.
Days of storage Trial 1 Trial 2
3                            87       90
8                            70       76
12                          60       50
16                          26       17
20                          17       13
23                            7         3
26-35                       0         0

Amy Marr

Greenfield, IN 46140

From: "roy pischer" <tlp4456"at"msn.com>
Sent: Wednesday, April 12, 2006 8:20 PM
Subject: Re: TRES colors

Torrey and list, we have one box with what appears to be very light blue
colored EABL eggs. What do TRES eggs look like? I have seen EABL in
the vicinity, but could it be TRES?

Trudy Pischer
Willard, MO

Trudy,
The shade of blue in Bluebird eggs varies quite a lot,
in my experience. Keith: Do you know any reasons for this variation?

Hi Trudy,

Eastern Bluebirds can lay white eggs (about 10% do), & i've seen very pale blue eggs as well. My boss says that the blue color fades during incubation, but i haven't really noticed this. (Due, no doubt, to the fact that i'm checking a trail of 100+ boxes once a week. If i had a backyard box...)

Tree Swallow eggs, as people have said, are pure white, sometimes with a pinkish tinge, & are smaller & pointier. TRES nests, tho, nearly always have a lining of feathers. Mine tend to use white feathers, probably from swans. (It always makes me think they're raiding a chicken farm. :-])

Good luck on getting a TRES nest. They're very fun to watch. (Especially when they call in their neighbors to help defend their box by dive-bombing the monitor.
...

Torrey Wenger
Kalamazoo Nature Center

From: Maria Pino [mailto:mfpino"at"comcast.net]
Sent: Sunday, April 16, 2006 8:35 PM
Subject: Bluebird egg question

Hello,

Three weeks ago I found a nest in one of my nest boxes that contained 4 eggs. A week or so later I thought the nest may have been abandoned. The eggs felt cold to the touch. Now a female is sitting on the eggs. Can these eggs still hatch after 3 weeks if she had stopped sitting on the eggs and then returned?

Thanks for your help.

Maria Pino
Norton, MA

Maria,

Maybe she was not setting on them before and now she is. They can go two week or more before setting on the egg.

Maynard Sumner
Flint, MI

Hi Pam,

I know this is kind of late, but i'm finally getting last week's e-mail answered. It's been one of those kind of weeks! :-)

---You wrote:
The first egg in my backyard boxes was laid yesterday, April 8, 2006. There is a second one today, and now that there are two side by side, I can see that one of the eggs is significantly larger than the other. I haven’t seen this before. It is not likely to be a different female as there would be three eggs in the box today. Both eggs are the same blue shade.

I have seen weirdly sized eggs before. Once or twice a year (out of 100+ boxes, so it's pretty rare), i find a "runt" egg, maybe 1/4 or 1/2 the size of the rest of the eggs in the clutch. I'm guessing that type of egg doesn't have a yolk, just the albumin. I have not seen a larger-than-normal egg, tho. What does the rest of the clutch look like?

Let us know how this all turns out.

Torrey Wenger
Kalamazoo Nature Center
Kalamazoo, MI

Hi Torrey,

I know how the email backs up!

The first egg was laid on 4/8. Four eggs were laid total (normal clutch size for here) and incubation started on 4/11, the fourth day.

The clutch consists of 3 normal-sized eggs and one larger one - I think. I guess it could be 3 smaller eggs and one normal-sized one, but I think that is less likely. As I said, the larger egg did not appear larger than normal until there was a comparison egg.

Unfortunately, this nest is in a box that I had mounted higher than normal in order to try to attract TRES. While I can reach it to monitor and stand on tiptoe to peer in, I cannot easily photograph the nest. It is on a hill so I can't use a chair or stool.

The nest is also the one that has some downy feathers and a chunk of rabbit fur in the cup. I've had the feathers before, and even horse tail hair, but the rabbit fur was a first for me.

This female bluebird is also much different than most that I have. She has been extremely wary of people and has not acclimated to us in the yard like most do by this time. Even with mealworms being fed during cold rainy weather, the male comes to the feeder, but she stays behind and begs for him to bring them to her.

I am fascinated at the extra observations that I am able to make for backyard boxes. The back wall of my house is almost entirely windows so I can watch them while working in the kitchen or eating in the dining room or just reading in the sun room.

Pam

Hi Pam,

....

I would think that if any egg was going to bigger than normal, it would be the first one. Wonder if it will hatch a larger-than-normal chick. I should ask our volunteer who raises chickens & ducks...

Torrey Wenger
Kalamazoo Nature Center
Kalamazoo, MI

The pigment is applied as the egg is laid, so sometimes there are white
splotches where the pigment did not cover.

Kate Arnold
Paris, TX

My female EABL finally decided to lay her first egg this morning. It is the
usual blue color but it has two good sized white blotches on it. What does
this mean?
I also have a Black-capped Chickadee that has finished a nest in another
box. No eggs yet.
Tree Swallows have put two claim "feathers" in a third box. No nest yet.
So far we have captured 45 HOSP. A grand RECORD for a season so far.

Ruth
Souderton, E. PA

Ruth,

I think Keith posted on this last spring. I often see this with newly laid
EABL eggs. I believe it is bird feces on the eggs as they are laid. As the
female turns them, the gunk gets cleaned off eventually and you will have
blemish free eggs. What you have described happens often in my nestboxes
and is nothing to worry about.

Paula Z
Powell (Central) Ohio

From: Bob Franz [mailto:bluebirds.bob"at"gmail.com]
Sent: Wednesday, May 10, 2006 12:56 PM
Subject: Carrying and Laying of Bluebird Eggs

Hi Bluebird Editors,

As I make the daily rounds on my bluebird trails, I receive questions surrounding the laying of Bluebird eggs that are not answered in the Cornell Bluebird Monitor's Guide. The Guide addresses when a female decides to lay her eggs and that someimes she doesn't lay any, but more detailed information on conception and how eggs are carried by the female is missing.
Might this subject make an interesting article for Bluebird by providing answers to questions such as?:
o Do all eggs of the female get fertilized at the same time?
o If yes, and they grow at the same rate, why is only one laid per day?
o If no, is each one fertilized on successive days thus corresponding to them being laid on successive days?
o How long does it take a fertilized egg grow to maturity before it is laid?
o Can the increased size of a female who is carrying multiple eggs be detected?

Bob Franz, Bluebird Monitor in Orange County, California

From: Robert Barron [mailto:rebarron"at"gmail.com]
Sent: Wednesday, May 10, 2006 1:28 PM
Subject: Re: Carrying and Laying of Bluebird Eggs

Hi Bob,
That's a great idea. Here is a link to a technical article published in Condor titled: Avian egg size: variation within species and inflexibility within individuals. It's pretty technical but interesting.

http://www.sfu.ca/biology/faculty/christians/pubs/Christians2002.pdf

Thanks,
Rob Barron

Howdy, Bob:

Great questions!

FYI ... In addition to being absolutely obsessed with bluebirds and other cavity nesters, I am also crazy about my canaries. Through many years of breeding and close observations of them, I may be able to help shed a little light on your questions. (While obviously not the same species, the overall "mechanics" are the same.)

> Egg laying is a very hard on females. In fact, male canaries often live for 12 to 15 years ... but females that are actively reproducing rarely live to more than 4 or 5 years of age.

> Once they mate, the sperm is viable in the female for approximately four days. On my prize male birds, I regularly use this fact to father broods with multiple hens during the very same breeding cycle.

> In the production of a given a egg, consolidation of the calcium for the shell takes time ... approximately 24 hours. In fact, without adequate sources and supplies of calcium ... hens will lay their eggs with minimal shells (i.e. "soft-shell") or even without shells! Under certain situations, females (and males for that matter!) will eat their own eggs for the calcium contained in the shells. The shells of freshly laid eggs begin hardening immediately after being laid.

> It is somewhat easy to tell if a hen is carrying an egg ... especially when she has formed the actual shell. It is also interesting that if a female fails to the lay the egg, she can and often does absorb the egg back into her system.

I hope this helps,
David

I can't answer all of Bob's questions, but I did recently learn that it takes approximately 24 hours for a songbird egg to develop; fertilization takes place shortly after an egg is laid (for the next day's egg). I spent a morning a few weeks ago with someone who is studying white-crowned sparrows here in Seattle, and this is what she told me.

I'll bet there's good information on this in the Handbook of Bird Biology published by Cornell. (I don't have it yet, but it's on my wish list!)

Mike in Seattle, Michael Donahue

Bob asked some good questions. I did a bit of research for an article i wrote for the local paper (the nature center has a weekly naturalist's column), & this is what i found out.

Q: Do all eggs of the female get fertilized at the same time?

A: No. Only one egg is being formed at a time.

Q: If yes, and they grow at the same rate, why is only one laid per day?

A: <see next question>

Q: If no, is each one fertilized on successive days thus corresponding to them being laid on successive days?

A: Yes. The egg yolk (or oocyte) is fertilized as it starts down the oviduct.

Q: How long does it take a fertilized egg grow to maturity before it is laid?

A: It takes about 24 hours for the yolk to make the trip down the oviduct. Along the way, it gets layered with albumin (egg white) & membranes. The shell is the last layer added. Even with years of selective breeding for increased egg production, chickens still take about 23 hours to lay an egg.

Q: Can the increased size of a female who is carrying multiple eggs be detected?

A: A female will only carry one egg at a time, otherwise it'd be too hard to fly. (An average bluebird egg is 1/10th the weight of the female.) I think you'd have to be very familiar with what a bird looks like to see a difference, like David does with his canaries.

Torrey Wenger
Kalamazoo Nature Center
Kalamazoo, MI

From: Steve and Cindy Groene [mailto:hausgroene"at"comcast.net]
Sent: Sunday, July 09, 2006 2:27 PM
Subject: Cracked egg

I found one of my EABL eggs cracked when checking the box on Friday morning. It does not look like a bird’s peck. I’m wondering if the female somehow accidentally cracked it. The nestbox is not in HOWR habitat and I’ve never seen a HOWR anywhere near my yard in the 6 yrs I’ve lived here. The other 3 eggs are fine, no further cracks in them. It looks like a depression type crack.

Anyone want to take a look at it I can send you a pic privately and see what you think.

Cindy Groene
South Lyon, MI

Hi Cindy,

I think that there is a good possibility that the egg was broken by
one of the parents. As keith has described, the process of making an
egg is almost miraculous, and sometimes not enough calcium is
available and the egg shell is thinner. I'd just keep an eye on the
rest and keep reporting what you see.

Feel free to send me a picture but I can't guarantee I'll be able to
figure out what happened.

Thanks,
Rob barron

I got a few photos the other day showing a nest where one of the eggs was dented. This happens when the female is startled and actually slams the eggs together as she jumps or launches herself off the nest. This might occur late at night say when an owl hoots near the box or a cat squalls right under the box or when the hot breath of a predator if huffing in the box or when a monitor startles the female taking a nap during the day.

For really valuable parrot eggs or other birds when the egg shell is damaged just a little they seal the small crack or dent I believe with fingernail polish. This stops the cracks from spreading and gives a little support to the shell in just a small area. These eggs are actually very hard and the developing embryo is also very hardy and does not want to die because of a small dent.

Remember there are reports of monitors who poked sparrow eggs all the way through with a needle and the eggs hatched. The biggest danger to a cracked egg is that the cracks will continue to expand and at some point collapse before the egg totally is supported by the developing bird. Cracked eggs also allow ants to get between the edges of the shell and eat the developing baby bird. Bacteria and germs can possibly get through the egg membrane and run wild through the contents before the baby bird can develop.

Anyway a couple drops of fingernail polish on a cracked egg might provide a weeks worth of protection. I use a product called "NEW SKIN" for small cuts or to seal chigger bites and fire ant bites but New Skin seems to just be expensive water proof fingernail polish. KK

Hi Keith,

Many bird researchers use non-toxic substances such as the surgical glue Nexaband or just plain candle wax to repair hairline cracks. When using candle wax, they let the wax drip from a melting candle and apply only enough to cover the crack. Since gas exchanges take place across the egg shell, it's important not to covert anymore than is just needed to make the seal. Here's a link about Nexaband: http://www.entirelypets.com/nexliq15ml.html

--rudy in maryland

....

7/19/06- 1st and only egg so far!

Here is a picture of the egg
http://img142.imageshack.us/img142/8523/dwarfeggqf6.jpg
Only about a third the size of normal eggs. the female has been brooding
it for almost a week now.

Best regards,
Glenn
N. Central PA

You need to keep that egg. They sometimes call this a dwarf egg it will have little, possibly no yolk and it will not hatch. You see one of these about every 3,000 to 10,000 eggs normally. Keith Kridler

From: Bet Zimmerman [mailto:ezdz"at"charter.net]
Sent: Friday, July 28, 2006 10:05 AM
Subject: weird eggs

I did a little webpage with photos on weird eggs, including some more info about dwarf eggs like the one Glenn found in a bluebird nest. http://www.sialis.org/weirdeggs.htm

Comments/feedback/suggestions for improvement are always welcome. If you have any weird egg photos I could add, that would be wonderful.

Bet from CT

Interesting photos, Bet. Now I have a question -- are Eastern Bluebird eggs more green than blue? The egg in the photo looks green to me, and all the Western Bluebirds eggs I've had in my nestboxes are definitely pearly blue.

I noticed that in some birding books bluebird eggs are described as being "green". The eggs I have seen have always been blue, similar to a Robin's egg color.

I'm sure there are individual variations among bluebirds, but I wondered if there were a difference between Eastern and Western birds eggs?

Barbara in cool Cloverdale (only in the 60's this morning!) CA

From: Evelyn Cooper [mailto:emcooper"at"bayou.com]
Sent: Friday, July 28, 2006 12:28 PM
Subject: Re: weird eggs

.... my Eastern Bluebird eggs are a beautiful light blue. Some are bluer than others, but they are definitely not "green".

Evelyn, LA

I have not seen any EABL eggs that looked green - only blue, or white. I have seen some that are paler than others. Maybe it's your computer screen!

Bet from CT

The egg appears green due to the lighting. In normal daylight it is typical
"bluebird egg" blue.

Barbara,
All the Bluebird eggs that I have ever seen in 20
years are blue - the bluest of blues.
Bruce Burdett SW NH

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