Expert: Julia Booth - 7/12/2008

Question
QUESTION: hello, my ? is...we have had the same Robyn nest outside my door in a wreath.she has had 2 clutches so far, in the first all babies hatched and flew away, now on this second clutch i noticed that they should have hatched like a week ago but have not..so the last couple of days an egg has been missing..we had 4 then 3 & so on and now this morning she had 2, within the past hr they are gone. i have noticed that the nest is getting larger "fresh grass" is it possible that another female has taken over the nest or that the eggs were no good and she decided to get rid of them and is ready to have a 3rd clutch? any answer would be helpful..thank you

ANSWER: Have you seen any other birds? It's possible that another bird is taking over (stealing) her nest. Except that fresh grass is typically a Robin's nesting material. Incubation is 12-14 days. If you're sure you've gotten the time correct, the eggs may not be viable or they haven't been properly incubated.

I can't say for sure what's happening here. Keep observing and see what happens to the remaining eggs. Be on the look out for strange birds or other animals that may have eaten the eggs.

---------- FOLLOW-UP ----------

QUESTION: hello again, our robyn has had her 2cd clutch of eggs but as i said this morning they were all gone...we do have a lot of robyns in the neighborhood"up state ny" the first clutch hatched at 13 & 14 days...this last one did not get the chance i knew they should have hatched but i really did not pay close attention to the date "just a feeling" but noticed it seemed a long time...then today i saw fresh grass being weaved in the  nest & thought that just maybe another female took her eggs and kicked the other female out...its just strange that one day there are 4 then within 2 days they were all gone..i even thought about other animals but i have never seen any that come onto our porch...i was gone most of the day today and the nest is huge...i see no eggs though...could this also mean that the female knew her eggs were duds and she is going on her 3rd clutch?...thank you again...

Answer
Birds generally seem to have a sense of when they're eggs are good. Although some are not as bright as others -esp game birds, being on the bottom of the food chain. Chickens, for instance, are often rather stupid in this regard.

It's getting towards the end of the breeding season and some birds become competitive for nesting space. Many do kick one another out of nests. Robins will steal nests from other robins if they are unoccupied for even a few hours -commandeering and re-decorating for her own personal taste. This means her eggs must go as well. I suppose this is worse than the Cowbird and the Cuckoo who just lay their own eggs in the other bird's nest and lets her hatch them for her.