Egg On Ground - Put Back Into Suspected Nest

[birdman in buckhead]

Today, I found a normal looking egg (no cracks or holes - weight felt normal) on the ground directly under a PM house with 3 nesting PM pairs - 2 . ASY pairs, 1 SY pair. I had a sparrow problem when the ASY birds arrived, but I convinced the sparrows to leave and not return.... No starlings or other predators known. The 2 ASY pairs have been here about 6 weeks (I believe 1 pair is the SY pair that successfully fledged 5 last year, and the male of the other ASY pair stayed here without a female last year), the SY pair "hooked up" about 3 weeks ago. Although I spend a lot of time around the house - talking to "my" birds - I had not made any nest checks, until today. Both ASY nests have 5 eggs each, the SY nest has 1 egg. I assumed the SY female had just started laying eggs, so I put the egg found on the ground in that nest. What can I expect to happen?

[C.C.Martins]

Tough to tell, Id initially suspect any bachelor SY males. 5 to one egg per nest ratio is a lot; without checking its hard to tell if the nest with one egg had more at some point and a predator is getting to them or they are slow at laying; if your finding eggs on the ground somethings dumping them. Perhaps its the parents, bad egg?
Id suggest regular nest checks, fun and rewarding to know they will allow you to interact.
Good luck this season!
Tom

[birdman in buckhead]

Thanks for the reply. My first thought was "bad" egg, but my wife convinced me it had to be put back - that led to the nest check. NOTE: The nest with 1 egg was the SY pair that arrived weeks later than the ASY pairs, (as you know, the males all arrived first then convinced a female they were worthy mates). Considering that I thought the SY pair had just started laying eggs, so that's where I put the egg found on the ground. As of today, (12 hours after putting the egg in the nest), it's not back on the ground so I guess the birds are trying to incubate it. I'm going do another nest check tomorrow to verify the egg is still there and the SY female is laying more eggs. QUESTION : Once eggs are laid and incubation started, will the PM abandon the nest/eggs long enough for a sparrow to cause damage or if the sparrow encroaches?

[-=DKC=-]

QUESTION : Once eggs are laid and incubation started, will the PM abandon the nest/eggs long enough for a sparrow to cause damage or if the sparrow encroaches?

Some pairs make sure one of them is always with the eggs/chicks. Some pairs will leave the nest unprotected.

So yes, there is always a possibility of House Sparrow mischief if the parents leave the nest unprotected. Hopefully your birds will all be the protective type.

[C.C.Martins]

Yep, youll find the younger birds have not learned the nest guarding. They learn the lesson the hard way, when the chicks are older we can worry less. Good that you caught the egg outside, whether or not it survives good job.

[Conrad Baker]

I would have marked the egg with a pencil (maybe an X), so that you can see if the Martins dump it again. Also by doing nest checks, you could see if the egg with the X is pushed aside, or maybe even hatches when some other ones start to hatch. I think the Martins might have pushed it out.