unhatched eggs

[jeff gregory]

i was cleaning out my gourds the other day to put up for the winter when i noticed in one of my gourds they were 4 unhatched eggs. what do you thonk could have happened? input is greatly appreciated....
thanks,
jeff gregory

[Linda Reynolds]

Jeff,you reported that you found 4 unhatched eggs in ONE nest, that indicates the loss of a female adult.

Sometimes adult martins are attacked by predators while out feeding, and if the female did not return, the male cannot incubate the eggs. Sometimes that nest is reused by others. If you have a highly populated colony, SYs will sometimes build a nest on top and raise their own family.

If you found 4 eggs in four different gourds.......that just sometimes happens. Sometimes within a clutch of 5-7 eggs, there is a dud. The parents know something is not right and will sometimes remove that egg or push it aside.

If you do regular nest inspections you can tell if there is a non-viable egg after the other eggs hatch. I remove any un-hatched eggs after 5-7 days after the majority of the clutch hatches. I would suggest doing nest inspections during the season if you can lower your housing. If you know what is going on inside each cavity, you can remove the eggs that have not been incubated and give another pair of martins a good opportunity to nest.

** edited note** Jeff, I should qualify my first statement........perhaps the male was lost and the female abandoned the nest. There is no sure way of telling if this happened, but is a possibility.

[Don & Danielle]

Jeff -

I agree with Linda - it's most likely that the female was lost.

But, for us the past two years, we have had one nest where I know both the male & female were present, yet none of the eggs hatched. Last year, the female appeared to be a SY female, and the eggs looked smaller than normal. Although she seemed to be incubating, none of the eggs ever hatched. And this year, we had an ASY pair (one of the first pairs of the year) who faithfully attended to the eggs, yet none of them hatched.

I think that sometimes, PMs can have "fertility" problems, just like people.

[Perry D. Vogel]

I had an ASY female and ASY mail pair who had five perfect looking eggs this year. All five were completely infertile. The female incubated those eggs for at least 20 days and then gave up on them. The pair stayed around until the remaining colony flew south for the winter.

[Jim Beatson~SC]

Jeff,

I think I've seen the "fertility" problem mentioned above. I've had a very old looking female come back very early in the year to adjacent gourds the past 2 years and lay 5 eggs each year. She sat on them 20 to 25 days and none ever hatched. Of course it's possible she chose the same infertile male each year.

Jim

[Craig Dyer]

Hi Jeff,

I have unhatched eggs every season at my colony. This past season an ASY pair laid seven eggs. They faithfully tended those eggs well into the summer. None ever hatched. Toward the end of the nesting season (in north Texas that is late June, early July) the female laid four new eggs. Of those, two hatched and one survived. The lone nestling fledged in early August. I am surprised that it survived as the high temperature was in the low 100s for many days in a row. All of the other martins and their young were long gone. It is a mystery to me why none of the original seven, and then only two of the last four, eggs hatched.