I posted on Facebook about the moral/ethical dilemma I'm having tossing that egg. I got a lot of responses that also really educated me, which I love. Several people (a couple of them bird people) suggested just blowing the egg and returning it to the nest, as the cowbird can be very vindictive and when their egg isn't in the nest they'll sometimes destroy the eggs that ARE there. What do you think?
Ronni, I do not know the cowbird...but I find the behaviour not "nice". I can imagine many pro's and con's to this question. As you know, I do bird conservation and stats here during the breeding season. I once encountered a situation where there were eggs of two migratory bird sorts in one nest. I did not know what to do about this situation, so I called the head of our area, laid out the sit and asked his advice. The choices were these (in random order): 1---Do nothing 2---Remove the oystercacher's eggs, and leave the others 3---Remove the godwit's eggs, and leave the others He suggested removing and destroying the godwit's eggs. At that time the godwit had not been made our national bird. The motivation was that godwits (like most of the migratory birds we get nesting here) do not feed their young--they must feed themselves although the parents offer protection and warmth until a certain age. However the Oystercatcher DOES feed its young, so his reasoning was that the offspring would therefore have a better chance of survival. It was a little difficult for me to do this, but I had asked... and NOT following his advice would definitely not have been good form. This all goes to show that you need to reasearch it and take a decision and stick with it--after all, the impact would not be a great one in the context of the "big picture". The obvious choices are to Terminate the paracitic behaviour and destroy the cowbird's egg(s), and leave the wren's. ...or to let nature take its course--you realize what the result will then be. Personally, I would let my heart rule on this one as the impact will be low and it has to so with your personal milieu and its inhabitants. I have to make choices like this every season with gardening--mice, rats, moles, wasps, magpies that kill and eat the robins, tits and so forth. Biologically speaking, it is not the correct thing to do and cannot be argued otherwise scientifically. I know that, but then I am limiting this unscientific personal behaviour to my own little plot of land, and thus right or wrong, I intervene with all the best intentions of my birds, crops and bees, in spite of scientific correctness. Naturally, YOU must decide for yourself what you will do, but do not wait too long...otherwise the choice will be made for you. Should you choose to remove and destroy the cowbird's egg(s) then I would suggest using some sort of chicken wire to isolate the nest from further cowbird visits--the wren will be able to squeeze through the holes in the chicken wire, but not the cowbird. Try and acquire some small-gauge chicken wire. The holes in the chicken wire must not be larger than 25mm. You may have to use a quite large piece to properly enclose the wren's nesting area. If you have to buy a whole roll from the garden centre, no worries--you can use the left-over for protecting your newly sown seeds or plants from marauding wildlife pests. Well Ronni, whatever your choice...please keep us posted on the nest's progress. It is an interesting thread.
What an interesting thread. I had no idea there were birds that would lay their eggs in another bird's nest.
Hey EJ! Is that you or am I reading an old post???? So good to see your smiling face again I wondered if that was a cowbird egg. I've never seen one but read an article about it and they are not good birds, kind of like our starlings I would love to have a wren nesting at my house.
Ronni, being this side of the pond i did at first think,..Cuckoo,..but i am pleased that Carolyn spotted that it was a Brown-Headed-Cowbird egg,..just as bad if not worse than the Cuckoo and if the Cowbird had its way there would be nothing else around but Cowbirds,..there are not too many Cuckoo's around but lots of Cowbirds,..getting rid of that egg will save all the other chicks in the eggs,..and prevent the Cowbird from growing up to kill of many more birds
OK, so the fern and that nest is at Ed's. I'm not over there all the time. I agonized over what to do with that cowbird egg...let nature and the natural order of things take its course, or intervene to protect the other babies and run the risk that the cowbird mom would attack. ...............and by the time I was back over there and checked the eggs again, they were warm!!! And I just could NOT bring myself to stop the process at that point. Call me a wimp, but I just couldn't. Here's Mama Bird keeping a sharp watch over us when we sit out on the porch. So then I was back this weekend.......and.....and this happened!!!! I'm both happy and sad. Such a mix of emotions. I can't really see how many babies...the egg that you can see looks like it's just the shell, so I'm assuming they all hatched. I'll check on them again Tuesday. I still can't believe how fast this whole process evolved!!!
I'm going back over to Ed's tonight for dinner. I'm curious, and admittedly quite nervous as well, to see what's going on in the nest now.
