The Intelligence of Instinct

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By Glenn Spurrell

The House Wren had just arrived back, and as predicted he started investigating the birdhouse in my backyard almost immediately.

You might remember I reported that White-breasted Nuthatches had taken up residence in this house this year quite early in the season. I knew the wren would be vexed. And I also know wrens can be quite unpleasant with other birdhouse dwellers (taking over houses, pecking eggs, etc). I was out gardening on a beautifully sunny but cool morning in late April when I witnessed a very strange ornithological event. The wren came to the hole of the birdhouse and the female nuthatch, being in the house, scared him away by popping up to the hole from the inside. But it’s the next event that is the surprising part. The wren came back and from across the yard another bird hurled itself causing the wren to take flight. I expected it was the male nuthatch but I was wrong: it was a phoebe! Now phoebes are one of our native flycatchers; and phoebes don’t nest in birdhouses. So I was completely flabbergasted. I thought maybe it was only coincidence and the phoebe had actually been chasing an insect and the wren thought it was being chased away from the birdhouse. But that proved incorrect because the whole scene happened again, and this time it was totally obvious that the phoebe was indeed chasing the wren away. Why?! Phoebes don’t used birdhouses so why would they get it into their bird brain to chase a wren? I think I know why. Phoebes make their nest in rather obvious places, nowadays often under the eaves of a house–like a Barn Swallow except the nest is smaller and they use a lot of moss. And so if wrens are as wicked as I say, they may have an even worse reputation in the bird world and go after nests not just in birdhouses. I expect phoebes are programmed (instinct) to chase away wrens that are in their breeding territory. Lucky nuthatches to have such a neighbour!

The same day that I saw this bizarre drama, I saw a bird that I couldn’t at first identify. The Brown-headed Cowbird is, in some ways, an attractive bird. They migrate and this was my first sighting this year. It must have been an immature male because it hadn’t developed the adult plumage; but its size and basic colouring confirmed the identification to my satisfaction. But this sighting got me to thinking. The cowbird is one of those rare birds who, like the cuckoo, lay their eggs in other birds’ nests. The nests’ owners rear the interloper as their own–this often means inadequate food and space for the rightful nestlings. Being raised with non-cowbirds must mean that there is no possibility that a female juvenile cowbird will be “taught” by an adult cowbird to find nests and lay eggs there. It must be pure instinct embedded deep in the genes.

For those who get out, let me report on a couple of things. In Medd’s Mountain the spring ephemerals are finally coming up. So go and try to get a glimpse of a trillium. And if you’re travelling on #10 just north of Millbrook, look into the wet area just up the hill on the west. The Marsh Marigolds are in bloom–what’s left of them after the construction work done there.

And finally, the first female Canada Goose to nest this year (on March 30th, huddling through snow and all sorts of cold weather) had her goslings on the pond on April 28th. This is tied with 2012 as the earliest in my time here. All other years have been May 4th or later.

Spring is here. Get out! And enjoy!

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