Thursday, June 3, 2010

A Tansy Dilemma

No sooner had I written that the chipmunk population was down in our neighborhood, we suddenly saw them everywhere in our yard. We hear their chucks in all corners, see them scurrying through the perennial beds and across the wood fence, their holes appear in unexpected places. And they are creating a bit of chaos in our yard.

Last weekend was high drama here. As I started to water the garden in the late afternoon, I heard a disturbance in the crabapple. I looked up to see the mother robin fighting off a chipmunk that was perched just above her nest full of four young. Chipmunks like bird eggs and nestlings. Normally I let nature take its course, but I've become attached to the robin and her offspring, watching them hatch and grow day by day. Plus, the chipmunk was clipping off our vegetable seedlings - peppers, eggplants, kale, Swiss chard. I was rooting for the robin.

The mother robin's antics managed to chase off the chipmunk, but it scurried back up the tree again. Here is where I intervened. The chipmunk climbed higher up in the crab. Srini brought a long pole saw and knocked the chipmunk out of the tree. The chipmunk landed safely. Kodi chased and pinned it, but the chipmunk squirmed away, and ran here and there before disappearing into the woods. We have not seen that chipmunk since. The robins and the garden are safe for now. I am anxious for the young robins to grow fast before the chipmunk tries again.

young robins waiting for a meal from their parents

Each morning we lay in bed before the alarm sounds, listening to the veery singing from the woods. I think about searching for its nest, curious where it might be. The veery builds a nest on or near the ground, and I had assumed it was in the woods, maybe beneath some ferns. But yesterday as Kodi and I walked a mowed path around our backyard we flushed the veery from a patch of tansy. The tansy that I was soon to dig up because it tends to spread and become invasive. I pulled back the tall tansy and there was the veery nest.

The nest had two beautiful blue eggs just like a robin; they are both thrushes. Strangely though there were two other eggs: white eggs with brown speckling. Brown-headed cowbirds are nest parasites, laying their eggs in other bird's nests. I am fairly certain that the veery is sitting on two cowbird eggs in addition to her own. When they hatch, cowbird nestlings are more aggressive and grow faster, sometimes kicking out the host bird's offspring.

Now I have a dilemma. Of course I'll  leave the tansy for now. But should I remove the cowbird eggs?

 The veery nest in a patch of tansy with two veery eggs and two cowbird eggs

Each time I walk near the nest I hear a chipmunk scurry away. I don't think it knows about the nest yet. After the young hatch and start making noises, the chipmunk might discover the nest, which is only a foot off the ground. This drama may well play out on its own.

2 comments:

  1. An interesting well told story. But I realize that it's more than just a story. There is a real dilemma.

    For what it's worth my vote is to remove the Cowbird eggs. As I recall one of Marcia Bonta's books had a similar dilemma about a snake and a nest and she let nature take its course. (I hope I'm remembering this correctly!). But in this case I just don't see a lot to be gained by more Cowbirds. I do know that Wood Thrushes are in serious decline though I don't think Veeries are as bad.

    Still I'd vote to remove them, knowing all the while how questionable it is for us to make decisions. On the other hand you were already about to interfere in the natural world by cutting back the tansy. So in one way or another we're always interfering, hopefully for the best.

    Good luck with your decision.

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  2. Hi Ken,

    But as my brother, who reads my blog, reminded me this weekend, cowbirds are a native species to the U.S., so it is actually illegal to remove the eggs. That makes my decision easier -- I'll let nature take its course. I haven't checked in a few days to see if the eggs have attached, but look forward to following progress of all the young.

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