High Summer

Blue jays are hated by most small songbirds, as they prey on nests, taking both eggs and nestlings. So it is not uncommon to see a blue jay being attacked (mobbed is the birding term) by a songbird, or a group of songbirds. Yesterday, I watched a blue jay being mobbed by an eastern phoebe: the phoebe flew at it, calling harshly, approaching the jay from above and below. The jay seemed unperturbed: one phoebe wasn’t enough, probably, to bother it.

Every so often the phoebe flew over to another tree—and here was where I observed behaviour I didn’t expect. Each time the phoebe landed, a red-eyed vireo attacked it, physically and fiercely. There was no clear reason for this: the phoebe is an insect-eater, no threat to the vireo except possibly as a competitor for food. When the phoebe flew down to the ground, the vireo didn’t follow it; it was only its presence in the tree that triggered the response. What I surmise was happening was transferred behaviour: the vireo, upset by the presence of the jay and the mobbing calls of the phoebe, did not differentiate between those two birds. It simply attacked anything that came near to it.

The Cooper’s hawk chick survived, and is now a juvenile, out of the nest and flying. I disturbed it on a path near the woods: it flew up to a tree-top, and sat there, calling. It’s tempting to anthropomorphize here: it was as if, scared by a human, it flew to a safe place, to call “Mommy….mommy…” If it was calling Mommy, she ignored it, at least as far as I could see.

Over on the grasslands the meadowlark brood is also flying, the juveniles easily distinguishable by their paler yellow breasts, for the most part lacking the black V. I’m pleased to see the successful breeding here – there are at least two pairs, each with three to five young. Eastern meadowlarks, like many grassland birds, are threatened, by changing agricultural practices and by climate change. Hayfields are harvested earlier, as grass varieties mature earlier, both from selective breeding of grasses for multiple hay crops and by earlier, warmer springs. But the grassland breeders need the long grass to remain until about July 1st, to allow their offspring to fledge and fly. Here at the arboretum, the grass fields remain untouched, allowing the meadowlarks to breed.

At the same time, the American goldfinches are just beginning to think about breeding,goldfinch males doing high display flights: they are our latest nesters, timing their breeding to coincide with the crops of thistle and milkweed seeds. The arboretum, especially but not only on the north side, has large stands of milkweed, which helps explain why there are so many goldfinches here. I check the milkweed patches on every walk, hoping for a monarch butterfly caterpillar: so far, no luck.

 

The first of the returning migrants will appear soon. Were there ponds here suitable for shorebirds, I would already be seeing the early ‘fall’ migrants, unsuccessful or very early breeders: they are being reported from other local birding sites. Southern movement of songbirds can and will begin any day now, birds that bred in the boreal forest heading for the rainforests of Central and South America. That a few grams of feather and muscle can make that flight once amazes me. That some of these birds do it for a dozen years has me completely awed, even after forty years of birding.

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