Bad eggs?

[Badger]

My egg numbers are way down from the last 2 years. I have been getting in the 120 range and l counted today 43 babies. Several nests has 1 or 2 half grown birds with 2 or 3 eggs that eggs were not damage. Several other nest with eggs were abandoned. Any thoughts. I'm a little dumb founded. I have 32 gourds. Thanks

[EarlG]

It has been my experience that a hatch rate of 85 to 90% is not out of the ordinary. Most are just infertile.

[Ed Svetich-WI]

Early sudies by the PMCA showed a significant advantage to providing calcium, specifically oyster shells as a supplement, in that it increased egg production and chick survival. Many just use crushed egg shells. If you are not providing a source of calcium, I suggest doing so. I supply crushed oyster shells and my colony hatched 485 eggs out of the 513 eggs that they laid(95%) over the last five years and consistently produce an average of more than 5 viable eggs per pair. The quantity of calcium consumed is surprising as egg laying approaches.

43 nestlings were the result out of how many eggs? What was your normal hatch rate? How many pair of martins did you support this year? If calcium is not the issue, are there any environmental issues that you can determine? Crop spraying for example. I hope you can determine the cause of your decreased numbers.

Good luck.

Ed

[Badger]

I had counted 46 adults. I put egg shells and crushed oyster shell on a tray for them. They really go for this. I do have 1 nest with 9 eggs. Maybe I just have a couple of infertal males this year. I only found 1 dead when I did my nest check and the adults seem healthy enough to me . it's a little frustrating.

[Ed Svetich-WI]

Strange outcome. With about 23 pair of martins, even if they averaged 4 eggs a pair, you should expect about 100 eggs. 9 eggs in one nest could include sterile eggs or be a case of egg dumping. Watch when hatching is expected to see how many hatch. In had a clutch of 10 eggs this year and they all hatched.

You could have something eating the eggs. Snakes come to mind but I do not know what your situation is regarding predators. Starlings or sparrow predation would be obvious. Since this is the second year that you are noticing this issue, weather issues are unlikely.

Next year, I suggest being even more vigilant regardling the number of eggs laid, hatched and also regarding predators and your colony. 46 martins indicates that you have had some success in the past. Keeping a record of the number of eggs in each nest would allow you to determine the exact number laid and hatched and may indicate where a problem, if any, lies.

Good luck in the future.

Ed

[Badger]

I have predator guards on my poles. The eggs that I looked at do not have holes or cracks in them. This is my 5th year as landlord and up until this year my colony has grown every year. I nest check once a week so if I see a problem I can take care of it early.

[Spiderman]

Did you have a severe late cold front that could have chilled some of the eggs so they wouldn't hatch?

The Martins will sometimes discard of infertile eggs or roll them to the edge of the nest.

[susanw77]

Newbie here, learning a lot. Question — what is egg dumping? TIA!

[Ed Svetich-WI]

At times, some females will lay eggs in nests other than their own. Egg dumping has been observed in over 200 species. Ducks are notorious for this, with some nests containing 30 or more eggs. I just had a nest with 10 viable eggs this year. Two eggs appeared on the same day. Obviously, one hen did not lay two eggs in one day. To make a long story short, all 10 eggs hatched. After moving several of the nestlings to other nests with young, allmare thriving as of today.

Ed

[Badger]

The weather has not been bad or late cold spells. Last week and this week it's in the 90s. I did install pvc elbow vents in my gourds before spring. Hope this will help with the heat.