DIFFERENT LOOKING BLUEBIRD EGG CLUTCHES – MARCH 2012

It’s fun to see how the egg clutches look on my nestbox visits.  Also, I watch to see how the female turns the eggs with her feet and how they change configuration for even incubation during those 14 days or so.   Some eggs have white marks in them; others with spots of dried blood.   When the eggs pass through the female’s oviduct, that’s when they are colored blue on the outer eggshell, through the pigmentation cells she has to allow this.   Occasionally, white eggs will be laid in bluebird clutches.   This means the pigmentation gene is missing during the egg-laying process.  Here are some recent photos I’ve taken within the past two weeks of the clutches I’ve seen this year.  You’ll see one photo (bottom right) required a mirror so I could see the set of eggs.  This can be challenging to do it quickly and get the picture before the adults get too nervous that I’m at their nest.  I try to make my nest visits as fast as possible and still get some good details!  This nest was built quite high and she placed more grasses inside the pine needle nest.  This is one of the reasons I enjoy other species using the boxes, not just bluebirds.  It’s really entertaining, as well as educational, to see how the species differ in their nesting habits.   I will be seeing the Carolina Chickadee and I’m hoping to see some Tree Swallows on my trail this year.   They are marvelous birds.  I wish I could spy on many different species nesting.  The live cams on eagles, red-tailed hawks, and others are fascinating.  The Cornell Lab of Ornithology has several cams going presently.  The hummingbird live cams are truly my favorite of all.

    

5 comments on “DIFFERENT LOOKING BLUEBIRD EGG CLUTCHES – MARCH 2012

  1. My blue birds keep laying eggs then they never hatch. They did this three times last year and twice this year. Why is this happening?

    • Wow, that does seem like a lot of unhatched eggs. Is this happening in the same nestbox both years? Is it the same female (sometimes hard to tell this)? I do have many questions I would need to ask you to see if I can help. What might be helpful is to link you to the unhatched eggs page to a very informative website on bluebirds. You may find your answers there. One of the questions I would ask is are other eggs hatching, and these are eggs in the same brood that never developed? Or does the female lay, incubate, and nothing happens, and you waited several weeks, and she never returned? Guesses at this point would be something happened inside the nestbox during laying or incubation that causes her to abandon…or…the laying female(s) or the male(s) is/are infertile. It is always good to leave species of eggs for a fairly long period and not remove them too soon with the thought they are unhatched eggs. Sometimes a female will delay incubatiion during high heat days or cold snaps. It is possible the incubating female was killed (predated upon). See if the Sialis site can help you troubleshoot. In my case, I’ve had more unhatched eggs than ever. I still don’t know why in some cases. Take a look here and see if this helps: http://www.sialis.org/eggsunhatched.htm I would love to hear back from you, if you figure it out. Come back here and leave another note as follow up. Good luck!

      • I know its the same male bluebird, he always taps on my window for me to feed him some mealy worms. He uses the same box and has found different mates to lay eggs. Last year the first female left and he brought another female over to look at the eggs, but I guess did not want anything to do with them. Then after I cleaned it out he brought another female looked at all the boxes on the property and picked the same box and laided more eggs..Then the female never sat on them.. I think this poor guy is sterle and keeps bringing these females back and they get mad and leave because they are not fertilized. I feel bad that they go to all the trouble to build a nest then lay one egg a day for four days then they are gone. What should I do? Board the house up? I hope each time when they build its not “HIM AGAIN”

        The females never incubate, so do they know right away that the eggs are not fertlized?

        • I would not deter any bluebird (or native cavity-nesting bird) to have a nest site, in my humble opinion. I say let them be and see how it works out. I would not close off the box from them. Instead, have fun with this and keep a log on the data. If you are not already reporting in your stats on your box to your state’s bluebird society, you should. It’s fun and the data is extremely helpful to ornithologists, particularly in this situation. There is a possibility the female might know eggs are not viable from her brood patch; that is, she does not sense the eggs are warmed. How long do you leave eggs in a nestbox when you sense abandonment from the incubating female? There is also a possibility (maybe not) that the females are predated upon. Give me a few weeks to do some research and come back here to reply more. I’ll be offline from this website for a couple of weeks but I will be back to reply more. Thanks so much for sharing. I know you want to see bluebird babies…sometimes it may not happen, but eventually it will again. Just the fact you are watching it and caring for it is a huge plus! That’s the right thing to do. As far as “him again”….he may or many not be infertile. Hang in and keep monitoring the situation. If you have enough property to space another box, put in another one. See what happens…you might get another bluebird couple using it. If not, enjoy what cavity nesters do use it. Spacing should be at a minium of 100 yards in open habitat with scattered trees for best success. You may not have that spacing available.

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