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House Martin Question (1 Viewer)


Senior Moment
A chap I work with has several House Martin nests on his house - part of a colony in the neighbourhood. He said that last night he was out on his patio when an egg fell from one of the nest. He was fairly sure the martins had pushed it out and asked me why they would do this. I suggested that maybe the birds had ousted it because it was infertile, but I wasn't sure so I thought I'd ask your collected wisdom. So: can House Martins tell if their eggs are infertile and would they chuck them out? Or is there another explanation?

dan pointon

Can't Stop
Hi Jason,

I've got House Martins nesting outside my window, and i've also been noticing some really weird behaviour off them too. Some of which, could possibly lead to an egg being knocked out of the nest. As it's been really hot lately, my window has been open all the time, and with the nest right by it, i can hear everything that goes on in the nest. The other day a lot of noise kicked up, so i went to the window to see what was happening. I was amazed to see 3 full grown adults crammed in to the nest, having what appeared to be a fight. (A lot of noise and the odd wing/tail feather sometimes pertruding from the nest). Then they all appeared from the nest, clung on to the wall, and flew off one by one. I would imagine fighting like this could cause an egg to drop out of a nest. Does anyone know the reasons for 3 adult birds entering the same nest, and if this could possibly cause an egg to drop out?




Super Moderator
Staff member
Another possibility is that the other eggs have hatched and as the young are growing either an adult or one of the young has pusshed the egg out.

d hood


some years ago i obtained a number of nest records for house martins in nestboxes - in at least some cases unhatched eggs were left in the box rather than removed. once, i found two hatched nestlings and one that appeared to be in the process of breaking out of the shell. a few days later, i found the (dead) chick - still in the egg - on the ground under the box. on another occasion, a brood of two recently-hatched nestlings (plus unhatched egg) had disappeared by the time i made my next visit about a week later. i could find no evidence of predation or any remains on the ground, so their fate was a bit of a mystery.

hope this helps



Senior Moment
Dan, that's interesting. My colleague did mention that three martins had been visiting at least one of his nests. I have heard that, with some species, unmated birds have so strong a breeding instinct that they will attach themselves to an established pair and help feed their nestlings. I think hirundines are among the species involved, but I could well be wrong.

Duncan and PC, thanks for your observations. Yes, I guess nestlings may well be responsible for that my friend's egg; I'll ask him whether any have hatched in that nest. It would seem a credible explanation for the fate of Duncan's chick-in-egg too.


Well-known member
I wonder if there is a link with the actions of 2nd cal (2yc) male Purple Martins. There is a lot of documentation regarding the actions of said, trying to infiltrate established nests, and causing havoc. Are we seeing a similar trait with certain House Martins.
A further bit of digging is required.



d hood


i think that in the first case i described the chick probably died during hatching and was then removed by an adult bird - the other nestlings were almost certainly too small to have been the culprits. as for the second incident, other martins could well have evicted the chicks/egg (the entrance hole was too small for sparrows to enter); the box was not reoccupied that year. on another occasion a pair of adult martins entered a box containing young, began fighting and sometimes pecked the nestlings. i did not know the identity of the adults and could not be sure whether the chicks were just in the way or were being specifically attacked (they all fledged successfully).
incidentally, the fascinating book "coloniality in the cliff swallow" (by charles.r.brown and mary bomberger brown) states that cliff swallows occasionally transfer eggs - and even nestlings! - to other occupied nests, carrying them in their beaks. sometimes, they also enter neighbouring nests and throw out eggs or chicks.


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